I N S E C T F L I G H T
1. The accepted theory and its critique.
The accepted theory of the origin of insect flight is not usually
called more than the "most acceptable theory". On the other hand its
weak points are not often discussed either. But by defining these
problems we can list a number of requirements that a theory of such
evolutionary process should meet in order to be convincing. This essay
presents an alternate theory in the form of reasoning based on existing
facts, and it will attempt to meet those requirements. Like any in
any mental exercise, the idea proposed here will be acceptable or
unacceptable only as far as the existing facts are correct and whether
the reasoning is acceptable.
OLD: A theory of the origin of insect flight should answer these
What is the anatomical origin of the wings and of the flight mechanism?
What function did these two have on first emerging which would be
adaptive and so guarantee their survival?
If originally these functions were not what they are presently, how
did changes in these functions occur?
What is the sequence of events that offers the minimal gaps in the
continuity of the development?
What support for the theory can be drawn from existing facts?
Has any of these original elements survived in some form?
Before going into the new theory it will be useful to review the accepted
rewritten till here 10/7 Sunday night
ACCEPTED THEORY 1
<[>Origin of wings and flight: "The...widely accepted
paranotal theory postulates that wings arose from lateral tergal expansions,
or paranota, of the thorax. It is maintained that the prothoracic
lobes of some of the most ancient fossil insects are organs of this
kind which had persisted long after the paranotal of the other thoracic
segments had developed into o wings. Paranotal expansions occur in
positions characteristic of wings, not only in the thorax, but also
on the abdomen in various arthropods; among insects they are seen
in many larvae and also in Lepisma, where they contain tracheae recalling
those of a wing pad. It is suggested that they became sufficiently
large to function as gliding planes or to control landing in leaping
insects. Later they acquired basal articulations which, along with
the development of muscles, enabled them to become organs of independent
flight. It is not improbable that at an early stage in their evolution
wings were concerned more with sexual display or temperature regulation
than flight." R. G. Davies, Outlines of Entomology, 1988 p.
There is also a tracheal gill theory, which is not accepted, because
wings and gills do not share the same anatomical development and "do
not seem to be serially homologous with tracheal gills". It is also
based on assuming that winged insects had aquatic ancestors, and this
is not supported by the facts. (ibid.)
ILL - Protorthopteran fossil reconstruction!
ACCEPTED THEORY 2
"It is now widely, but not universally accepted that insect wings
arose from meso- and metathoracic paranotal lobes, homologous with
those which occur on the prothorax of members of the Paleozoic order
"In these ancestors it is supposed that the lobes later came to serve
for delaying descent, as parachutes and then as aerofoils, those on
the meso-and metathorax becoming enlarged and MODIFIED
UNTIL M WITH ASSOCIATED CHANGES IN THE SKELETON, MUSCULATURE
AND NERVOUS SUPPLY OF THE THORAX, TRUE FLAPPING FLIGHT WAS EVOLVED.
THE PROTHORACIC LOBES BECAME OBSOLETE and ULTIMATELY
DISAPPEARED, AFTER PERSISTING FOR A WHILE IN A FEW LINES."
(R. J. Wootton (chapter The fossil record and insect flight, p.
ACCEPTED THEORY 3
(Wigglesworth):
"At the present time there is almost universal support for the paranotal
theory. Most authors suppose that the outgrowths were favoured in
selection by their ability to serve as planes utilized in gliding
from high vegetation to the ground. Hinton starts further back and
considers the first step towards flight to have been attitude control
of legs and body to ensure that the falling insect landed on its feet
and could make a quick escape from predators, namely spiders. Enlargement
of lateral outgrowths would be a later step in making true gliding
possible. Flower, who suggests that gliding could have begun in small
insects of 1 cm length even before lateral planes appeared, points
out that diminutive paranotal lobes at their earliest appearance could
have played an important role in attitude control.
"Then, as visualized also by Pringle, hinges to the planes and muscular
control of their inclination would enable large adult insects to exercise
control over the direction of gliding; and, finally, relatively slight
alterations in the muscular system would provide for slow flapping
flight. That is probably the most widely accepted conception of the
evolution of wings and flight. (V. B. Wigglesworth: The Evolution
of insect flight in Insect Flight, ed. R. C. Rainey,
Symposia of the Roy Entom Soc of London, 1976).
ACCEPTED THEORY 4 -- WOOTTON!!
The paleontological evidence, slender as it is, seems to favour the
existence in the Devonan a small -- c. 10mm? -- insects, whose initially
protective(!) thoracic paranota became enlarged in association
with their value first as parachutes, in delaying descent; next as
gliding surfaces; then as steering vanes, as they developed the ability
to slightly pronate, supinate, el;evate and depress the pads by action
of the pleural leg muscles."
end of Accepted Theory
CRITIQUE OF ACCEPTED THEORY
THE LOBES
Paratergal lobes refer to lateral expansions on any of the terga,
or dorsal plates. Paranotal extenxions, or paranota, refer to those
occurring on the thoracic terga, called nota (singular notum).ILL
The developmetn of wings from paranotal lobes seems perfectly logical.
The identification is built on the fact that the structure and anatomicla
relation is the same for both, that is the two organs oare homologous.
Namely both are folds of the integument, both are more or less extensions
of horizontal surface, and both are on located on the thorax. There
are abdominal paranota as well, but this ould not matter, but only
underscore the basic nature of potential for paratergal lobes.
Actually, the emergence of paranota, or more generally, paratergal
lobes, that is lobes occuring on any tergum, presents no difficulties
in its explanation: variation in size is a simple occurrence, and
paraterga are nothing more than increases in the lateral dimension
of the terga. Such extension meets no obstacles becasue it expands
into emtpy space. Longitudinal elongation of terga is much more limited
because there is little free space between plates, and any longitudinal
growth also involves the inside anatomy of a segment.
It is a fact that paratergal lobes exist widely among arthropoda,
both in fossil and recent insects. The basic plan ILL of
a paranotal lobe is that of a folding out of the body cover at the
edge of the notae(plural?). .
Paraterga are found on fpssil Trilobita and Cheloniellida, and on
Xiphosurida (fossil and recent horseshoe crabs). Paraterga may or
may not be present on Crustacea. Fossil Arthropleurida (gian fossil
myriapod has them. Among the Myriapoda, centipedes, pauropods do not
have them, but most millipedes do carry recognizable paraterga. In
the Insecta the lobes are mostly absent in Collembola, Diplura and
Protura, but show up to a small degree, and the THysanura and Monura
possess them on trunk segments. The basic innateness of paraterga
is evident not only in their frequent appearance, but in their repression
and later derepression in some lines, as well. "Porthoracic paranota
seem to have been redeveloped among some tropical mantids, and in
the insect familiy Peloridiidae of the Homoptera. (Boudreaux, p. 136)
Being extensions of the sclerotized tergum, the paratera are hardened,
therefore they effectively expand the protective area of the terga.
Since they enlarge the horizontal diameter of the insect, they would
also increase apparent size and thereby would be adaptive.
<[>There is apparently some adaptive value to a flattened, as-wide-as-long
body shape, typical in the Hemiptera -- which unlike hte Blattidae,
extermely flat -- does not need it for anability to hide in crevices.
Perhaps it has to do with the Hemipteran wing condition, where a part
of the wings is sclerotized. Does the flat body have areodynamic functions?]
At this point, therefore, a structural source for the lobes can be
convincingly demonstrated.
Edit this next paragraf and it will do. Summarize acceptable adaptive
roles for parategra and then go on to jump and glide.
NEW: If not adaptively useful, novelt structures tend to disappear.
The paranotal theory has no problems here. a small series of minimal
lateral extension of the nota readily increase the visual size of
the insect. To an insect relatively small increments appear more significant
than to creatures of our size. Therfore, it is possible for ancetral
paratergals extensions to rach a size where they would have aerodynamic
effects. But if flight does not originate from jumping or gliding,
than the paraterga would have no aerodynamic roles.
But considering that the lobes becoming hinged is a flight prerequisite
in the accepted theory we must picture such a hinged lobe. To a non-gliding
insect hinged lobes would offer reduced protection, but the insect
would still appear larger and would also move less encumbered in narrow
OLD <<OUT However, we can expect that the paranotal lobes on
initial emergence must have been unspecialized, relatively small outgrowths.
The adaptive function they possessed is difficult to imagine. But
there must have been one, or else they could hardly have developed
into the form seen in the fossil evidence. If a structure has no application
it tends to disappear, so it is important to find one.>>
It has been said (Wooton, p.236-237) that "<[>paranotal lobes are
probably secondary and serve such functions as eliminating of shadow
for camouflage, protection against predators, or streamlining, any
of which may also have been the initial function served by the primary
lobes of Pterygote ancestry." However, this view does take into consideration
the initial, primitive form of the structures.
NEW We must distinguish between the primitive, ancestral, sclerotized
paraterga, or extenions of the dorsal terga, and the apparently thin,
bladelike prothoracic paranota in the fossil record. The accepted
theory speaks at firts of an occurrence, a secondary development,
of the general ancestral tendency to evolve paraterga, and assumes
them to eventually become thin lobes such as found in the Paleozoic
Stenodictya and Lemmatophora.
NEW: Camouflage is conceivable if the paraterga, whether ancestrally
primitive or advanced to the lobe stage, are ILL longitudinally fused
and laterally extensive, because than they would cover the legs to
some degree, and make the insect resemble more a random natural object,
like a pebble, than a six-legged creature. But if the lobes were separated,
not joined, as they appear on the reconstructed Paleozoic insects
with prothoracic paranota, then such geometric spacing and form would
actually call attention to itself. The geometric designs on existing
insects are the opposite of camouflage, they are visual identifiers.
Protection is an acceptable adaptive function of primitive paranota
if they either visually enlarge or structurally protect. But protection
implies density and mechanical strength, both of which are likely
be absent in the lobes assigned to be gliding vanes.
Of course, we must distinguish protection from predation from protection
in interpsecies contest. What offers little protection against larger
predators, can be effective in rivalry among similarly sized conspecifics,
where thin paranotal lobes, acceptable for gliding, might provide
advantage even if not particularly strong. This fact avoids the problems
posed when applying the protective role of the lobes to a complete
range of insect sizes.
(There is also the insct's size. On a small insect ???)
Streamlining must refer to areodynamic surface control and would be
effective once jumping and gliding were performed. When speaking of
pre-glide streamlining the term must refer to ground motion. But here
little gain would be made by a lightly structured, distinct set of
lobes to be of profit here they would have to be strong and closely
fiiting together enough to be adaptive when burrowing, or more generally,
when moving through vegetation.
Accepted theory requires hinging, musculature, flexing. -- maybe nothing
wrong with that in theory. Still these are three devlopmental tasks
that are only treated generally in the accepted paranota thoery of
flight. In our search we will try to find an alternate theory that
can describe these developments in greater detail.
However, other, crucial developments, such as jumping, parachuting
and gliding, postulated by the accepted theory present a number of
JUMPING IN GENERAL
The assignation of jumping as the basis for gliding and then
flight evolution at first the sounds perfectly reasonable. But let
us consider some details, firstly the size factor. Except for the
Orthoptera, existing jumping insects do not measure very large. Collembola
(springtail), Syphenoptera (fleas), Homoptera (Spittle bugs (family
Cercopidae), leaf hoppers (families Cicadellidae, Membracidae, Psyllidae),
click beetles (Elateridae), cheese maggot (Larva of Piophila) are
all minute to small insects. At their size gliding would be present
practical problems because of the forces of aerial drag, air movement
are large in relation to the insect's small mass with which to counter
these. The simple fact that there are so few jumping orders can be
seen as indication of this problem. It is also significant that none
of the jumping insects perform gliding.
As for the Orthoptera, here we find sizable insects that jump. Yet
they -- who could easily do so with their highly controllable wings
-- are not noted for gliding. Among all insects only certain locusts,
Lepidoptera and Odonata have been observed gliding, but this is clearly
exceptional, and among these medium to large insects only the Orthoptera
are jumpers. We can conclude from the existing evidence that gliding
is not useful for insects in general. Opening the wings as part of
the an escape jump by grasshoppers serves not to glide, but to visually
confuse the pursuer. And since the lobes were supposedly helpful in
maintaining correct body orientation in jumping it is surprising that
grasshoppers do not attempt any aerodynamic control: the fact is they
are clumsy saltators, often landing upside down. They leap "...some
rising in strong light, others tumbling aside with clumsy leaps."
(Lanham, p.145). Other jumping insects pay little attention to proper
landing orientation; perhaps merely jumping with high enough speed
is satisfactory not only for insects but also for frogs. The escape
value of jumping arises from the fact that a pursuer's visual tracking
ability is outclassed by the speed of the leaping insect: a movement
of a sufficiently small object, travelling at sufficient speed, and
occupying a sufficiently large angle of the observer's visual field
can be impossible to track by a visual system.
JUMPING WITH LOBES
Except in the case of fleas (Syphanoptera), we think of insectan
jumping as a form of escape behavior. But if jumping with lobes is
presumed to lead to gliding and parachuting, we may point out that
horizontal extension of body surface decreases the escape time. Lobes
would oppose not only vertical movement but also some vector of forward
velocity. It seems that lobes offer little improvement in escape.
It may be significant fact that no jumping insect has developed any
glide control behavior or mechanism.
There is also the question of the orientation of the jumping body.
We can picture an hypothetical jumping, non-flying insect with lobes
to help it control the position of its body in three dimensions.
ILLS Do this as ill.s in a chart with text
NEW: 3:05 pm Having made models -- unless the lobe or wing plane
(or angle of attack) is the same as the plane (or angle of attack)
of jumping, the jumping body will be rotated on the axis perpendicular
to longitudiunal axis, or direction of jump. Therefore, only the insect
whose wing plane matches the jumping plane will move forward, all
others will go into rotation and fall immediately after take-off.
It is assumed that the insect does not alter the yaw of the body in
transit, fot this is not possible without movable lobe or wing plane
3:09pm SO, now this needs combining with abovE paragraph.:
CAPTIONS:
1. Here we have a jumping insect with immovable lobes, starting with
body parallel to the ground and maintaining it at the same attitude
through the entire 45o trajectory. In the horizontal part
of the trajectory the lobes will impede minimally, but they would
amply retard speed in both ascent and descent. At all three stages
the lobes would of course stabilize the attitude -- but only if provided
the air movement was favorable or at least negligible.
2. In a steep 70o, jump the forces opposing ascent and descent
would be further increased and gliding or parachuting would by slowing
the movement would present no advantage to escape..
3. In the case of a low angle jump the lobes be of minimally effective.
They would mostly lie in an approximately horizontal plane and would
help float the insect and therefore the escape speed would be still
be decreased.
As for the body orientation at the start of the jump, it should be
considered that insects, especially grasshoppers may often be found
in a non-horizontal, even near vertical positions on plant stems or
leaves. Granted the vegetation in the days of pre-flight insects was
different from that of today, plant growth is and quite likely was,
both horizontal and vertical, and so insects were likely to be found
in a non-horizontal position. If we take a present day case of a grasshopper
on a grass stem ILL we can see how horizontal paranotal lobes would
be of little service to an insect either landing on a horizontal surface
or on a vertical one. This
Would lobes assist a running insect? We read that "<[>lobes]
served as gliding planes and prolonged the motion through the air
of insects able to run or jump." (Pringle, Flight/Locomotion, p. 434).
Lobes would only assist a fast runner, but among present day insects
high speed runners tend to be ground dwellers, and their speed enables
them to quickly reach hiding places.
THIS IS OUT; NO POINT TO IT: Another problem for gliding insects,
whose maximum body size is limited, is air movement. For purposeful
gliding there must be some ability to control unfavorable effects
of breeze and wind. The evolution of gliding for bodies of
relatively small mass is potentially limited by such ever present
environmental forces.
As for parachuting, this action slows descent and so again
it is counterproductive for escaping. It is in nuptial display that
we can see a pragmatic use. Parachuting would be useful in a nuptial
swarm, where a mass of male insects would, perhaps repeatedly, climb
up on plants and would float down. Thus they would provided a visual
signal to attract females since placing visual objects higher permits
them to be seen from greater distance. Parachuting has also been assigned
to a theoretical pterygote ancestor climbing up high plants to eat
and then "descending on the enlarge paratergal outgrowths. As Hocking
notes, the appearnace of winged insects and high vegetation was almost
synchronous." (Sharov, p. 111) Such synchrony would indeed underwrite
the relationship of the two. However, except for relatively short
plants, feeding on plants that may be considered high at least for
insectan standards, there would be enough to eat both going up and
coming down, thus there might be nothing gained in jumping off.
As for gliding in non-escape situations, there seems to be no convincing
purpose. Insects generally have an interest in holding on to the substratum,
while sudden dropping or jumping are escape reactions. A basic proposition
of the paranotal gliding theory speaks of insects climbing up and
then gliding down, however, the practice of saving energy from ahving
to climb down after having climbed up is not found in insect behavior.
The proposed initial emergence of high plants as a stimulus for gliding
is less than convincing for additional reasons discussed below (under
Gliding with the paranotal lobes would, of course, make perfect sense
once flight had begun. At that time the expectedly primitive
flight musculature would benefit from periods of rest during flight
and gliding would provide. The prothoracic paranotal lobes on the
fossil Stenodyctia, etc. may be representing a stage where relatively
primitive flight control could be assisted by gliding surfaces.
NOT EVEN ALL ORTHOPTERA JUMP -- THIS NEEDS RESEARCH __
FIX Here is a question: considering that it is only the grasshoppers
and locusts among the Orthoptera that include medium to large sized
jumping insects, CHECK AND CORRECT: {and in this order of 5 suborders
and 12 families, only 2 suborders and 7 families are jumpers, why
should we think that flight is derived based on jumping?} could have
once been jumpers but had later lost the ability.
NO VESTIGE OF EARLIER SALTATION IN OTHER PTERYGOTA!
Another question concerning jumping as precursor of flight we can
ask is why no patent or latent vestiges of jumping structure or behavior
are found in any form among the great many families of flying insects?
Were jumping part of the original shared ancestry we could reasonably
expect it to have left traces or to have lead to additional developments.
We can also remark that among apterygotes, or insects without wings,
as well, jumping is the exceptional mode of escape or locomotion.
QUESTIONS ABOUT THE ORIGINS OF JUMPING --
DID SALTATION arise from stridulation IN ORTHOPTER? and NURSERY
How did jumping, using legs, originate? Jumping works through a relatively
gradual build- up of elastic muscular tension which is suddenly released.
The muscles involved should be of maximum cross section to yield maximal
force and alsp short so that their release would take minimal time
in returning to relaxed state. All this would need a context and time
for developing. How would such requirements be filled? It seems that
such development of unusual muscle triggering is possible based on
a anomalous triggering of muscles by the neural system, which alone
is responsible for such timing and perhaps the build-up of femoral
muscle mass would be a secondary development. Such evolution obviously
must have taken place with the various types of jumping insects, however,
with Orthoptera another origin for jumping can be postulated. This
is covered below, in SALTATIO ex STRIDULATIONE.
WHY IMPROVE ON JUMPING ANYWAY?
Even if a closely controlled and selected development of an aerodynamic
surface to modulate jumping may be conceivable and available, the
question remains: is there any reason to improve on jumping? Jumping
is certainly an effective method of escape. An insect that leaps disappears
because its speed is not successfully followed by the visual system
of an observer, and as long as the insect is no longer seen, the jumping
ability, whether ending with legs ready to grip a substrate or not,
is positively selected. After all, jumping is mostly rather successful
for grasshoppers, at least from human attention. But if birds and
mammalian carnivores are better at it, they were not around in the
formative era of flight when on land only primitive vertebrates existed,
and predatory insects were equipped with nothing better than insect
vision. If these conditions of predation prevailed in early times,
jumping may have needed no improvement.
FLIGHT MECHANISM
At this point let us consider the flight mechanism. There are three
types of muscles involved: direct, indirect and accessory. ILLS
The wings are moved up by an elastic downward deformation
of the thorax through the pull of the dorsoventral muscles connecting
the sternum, or bottom and the dorsum, or top of the thorax. This
is the indirect muscular mode. In the direct mode, the wing is pulled
down by the dorsopleural muscle which comes up from the sternum to
the pleuron, or side, just under the wing hinge and through a short
tendon it connects to underside of the wing. The small accessory muscles
found at the wing hinge area act serve to control the flexing the
wing needed for directional control.
The dragonflies (Odonata) and cockroaches (Blattaria) fly the way
just described. But there are two other variations. In moving the
wings down the beetles (COleoptera) and grasshoppers, crickets and
katydids (Orthoptera) add an indirectly acting muscle to the direct
one. The indirect muscle, the dorso-longitudinal, contracts the thorax
longitudinally and acts through a reversal of thoracic deformation
caused by the other indirect muscles.
The third variation appears to show advanced development, evolved
for high-rate wing beat on relatively small insects. The true flies
(Diptera) and the wasps, ants and ? (Hymenoptera) move their wings
both up and down indirectly through the alternating deformations of
the thorax. The direct muscles, attached to the base of the wings
also act in twisting the wing as required for proper flight. Many
of the direct wing muscles are attached to the coxa, or base of the
leg and are in fact functional in leg movement.
The fact is that the wing musculature seems somewhat removed from
its purpose, as if it had been originally designed for another task.
The indirect muscles thoracic muscles which existed long before flight,
and most of the direct muscles must have originally served only the
legs. This would not be a problem since in evolution unexpected developments
often occur. Such as ears and jaws descending from gill arches are
obvious examples. Nevertheless, in describing the evolution of moveable
wings from stationary lobes there are no clues to lead us to anything
but the most general hypotheses.
AND ALSO DON'T CALL IT CRITIQUE! JUST QUESTIONS!
SUMMARY OF WEAKNESSES IN ACCEPTED THEORY
Now that we have presented the main questions concerning the accepted
theory of flight we can list points where the hypothesis answers and
where it does not.
Reorganize whole thing here. Cut out lecturing and other theatricals:
Best to do: first bring up oxypragma only at membrane
+ modulator adaptability
CUT ALL THIS PREREQUISITES TO BE FILLED! DON'T SOUND PETTY!
Summary of problems with Paranotal Theory of Flight
FIX: HAving cut out the above: just say the weak points of Est TH.
are such and such, and say that perhaps an alternative theory can
be found, approached from a different direction, -- and nothing else.
Dont go into the lecturing form about fulflling any prerequisities.
New
1) It does offer a credible anatomical origin of wings from for paranotal
2) To explain the development of paranotal lobes into moveable wings
that is free of questionable details, such as jumping, gliding and
parachuting, it does not offer a sequence.
3) It offers no strong existing supporting facts, or any survival
or intermediate functions to support the propsed development of flight
from paranotal lobes.
4) It offers no basis for the development of the flight mechanism.
5) In general, it does not provide a continuous account of the entire
sequence of flight evolution. !! fix DO I?
LESSONS LEARNED AND A PROPOSAL: A NEW THEORY THAT AVOIDS THESE PROBLEMS
AND MEETS THE REQUIREMENTS: ontology, oxypragma, polypragma, synechia
and support
Keeping in mind these remaining questions we can list the requirements
needed to construct a more convincing hypothesis that will account
1) The physiological source, or ontogeny, of the paranotal lobes
or of alternate sources of the wing's ancestral ontogeny.
2) The immediate functional applicability of the original, most primitive,
lobe structure. This is necessary to provide an adaptive function
for the new structure, without which it would tend to disappear.
<<Since we shall refer to this concept often, it might be practical
to use the term oxypragma. As an example of oxypragma is exhibited
by the fins of the flying fish. Provided other conditions such as
body size and weight, fin surface area and speed of movement are set,
the fish, leaving the water at a low angle will glide because the
fins, normally used for swimming now immediately provide an instrument
for gliding, and so may be called oxypragmatic for gliding. Such a
situation is usually termed pre-adaptation. However that term has
associations with unconscious pre-planning and so may be better termed
as immediate applicability
or oxypragma.>>
3) A physiological basis for the ontogeny and development of the
flight mechanism.
4) An acceptably detailed and continuous account describing the stages
of the evolutionary sequence of flight. The classical example
of an ideally documented continuity is the evolution of the horse.
5) Support for the theory drawn from presently existing facts.
As an example we could cite the case where to support the idea that
humans descend from furry primates we were to point out that the human
body is almost totally covered with hair, although of very small size.
itt tartok Sun
3.3 LOOKING FOR A NEW THEORY
O L D
READ AND CUT: 10 pt. -- Originally
there is no basis or necessity for the lobe appendage to be moveable.
If immoveable, the lobe could only help in gliding, but this idea
has beeen shown to present complications. The important question is:
what was the absolute size of the lobe when it first became existent?
How large did it have to be to be considered existent? Clearly there
is an undefined range of size wherein the lobe would be present yet
not of a sufficient size (or form) needed to perform aerodynamic functions.
How large does the pre-lobe have to be for performing an adaptive
role? So far the fossil record has not shown any clues to these questions.
Some function must be found that would enable the emergent lobes to
perform an adaptive role; oxypragma must be demonstrated for the earliest
form of the paranotal lobes.
itt tartok
NEW: We start off with the accepted ancestor of the wing, the paranotal
lobe, but we will try to find (an) alternate adaptive role(s) for
it. (Develop all this a bit longer)
Just to have a relatively unbiased starting point, with no special
direction in which to start off, it might be helpful to stand back
to take a general overview of insect behavior.
4. PANORAMA OF INSECT BEAVIOR TO FIND POSSIBLE APPLICATION FOR OBSERVED
LOBES. (from fossil)
Insect behavior can be classified and listed as:
Sensory perception
Basic responses and patterns of behvaior (Reflexes, learned and instinctual
Peridocity and clocks
Orientation, navigating, homing
Host selection and feeding
Parental care and presocial behavior
Population behavior
Behavior, genetics, evolution and speciation
Eusocial behavior
NEW: Let us go backwards, starting with the accpeted picture of the
typical insect with protolobes used in jumping. ILL folssil
protolobe ancestor (Lanham, eg).
How else could a such a paranotal extension of the tergum function
adaptively?
IF thin and ...then ... so let us go back in time to where they were
primitive sclerotized extensions of the terga.
What use could they have aside from protective, and similar topics
covered above?
I THINK THIS NEXT ONE IS OK!!!
OLD
4.2 <<However>>, when looking into communication behavior, we do
find certain options, because we know of many small structures in
existing insects that can play a role in sound production. We are
talking about minute appendages, serrated, striated or otherwise designed
for sound production. It therefore stands to reason that a proto-lobe,
being a small expansion of integument on the thoracic side can be
rubbed by spines or pegs on the leg to produce a stridulatory sound.
Doing so we, as a matter of fact could claim to have found an oxypragma
for the proto-lobe. For even at a minimal size, beiong only a surface
irregularity, it immediately possessed a capacity toward adaptive
applicability. The exact meaning of the term "immediate" is debatable,
nevertheless, in the case of integumental folding we can define it.
Since the integument has a definite, measureable thickjness, when
folded it would be twice as thick, this being the minimal diameter
of an evagination even as it fisrt came into existence. As for the
extension of its plane surface, this would be determined by the extension
area produced by a minimal folding. ILL
At this point connecting the proto-lobe with sound production directs
us to further examine this insect sonification.
write this better: The area of behavior where wings and
their movement are directly involved in non-flight actions is communication.
Wings take part in two varieties of communication, sound production
and visual siognalling. Let us take each in turn in examining for
possible useful leads. WHERE DOES THIS GO?
4.3 INSECT SONIFICATION
Sound production and associated behavior is widely distributed among
insects. Functions of sonification include self-protection and escape,
since many insects emit sound when captured or disturbed. Insects,
such as crickets, advertise territorial claims by sound. But the most
frequently encountered and best known form of sonification is in courtship
and mating display.
IMPORTANCE OF SONIFICATION
It is clear why the use of sound in communating is important for insects.
Their visual system is limited and they are small so to spot each
other they would have to be close. By sending and receiving sound
waves, they effectively increase their distance of communication.
And because there is much variability in the ways sounds can be produced,
sonification at an important step of the genetic selection process
would also lead to a higher rate of evolution.
The significance of sonification is evidenced by the diversity of
methods insects specialize in for sound making.
Insects have to see things at short distances, mmilimeters or centimeters
away, and therefore they have a They cannot see far beacuse a lens
that has to see things at close distances FIGURE THIS OUT!!! WIDE
ANGLE LENS VS TELEPHOTO
WIDE SPREAD USE AND FUNCTIONAL ADAPTATION OF SONIFYING IN INSECTS
A great number of insects communicate with sound and they employ all
available body parts to make sound.. Their discrimitnation between
sounds and sound patterns can be quite refined. Mosquitoes can distinguish
among different high frequency wing hums. sme grasshoppers,can synchronize
their sonic emissions with that of nearby individuals.
Was sonification present in early, pre-flight insects? Flight and
wings themselves are tools of visual communication, therefore pre-flight
insects lacking these would have an even greater need for sound. Being
permanently anchored to the substratum, that is the ground or plants
(or animals) would decrease the insect's visibility and size of area
they could cover in in their searches. For this reason it is can be
assumed that the pre-flight world of insects was richly endowed with
ways of sonifying. The fact that a number of larvae and even pupae
produce sound may indicate to what primitive stage sonification reaches
back in the insect history.
If making sounds is therefore as wide-spread, perhaps(?) more
so than flying, perhaps even more, if larvae and burrowing insects
(Tenebroids??) use it, then it is likely that sonification is very
ancient behavior and certainly PREDATE flying.
VARIOUS METHODS OF SONIFYING
Stridulation is perhaps the best known method of insect sound
making. Here scraping or rubbing together a body part against another
with serrated surfaces produces a sound. Grasshoppers, crickets are
outstanding stridualtors. The function exists in a great many Orders,
and practically all body parts are employed. Stridulatory organs can
be found on the head (Nitidulidae, Erotylidae). Some "tenebroids beetles
(wood-boring?) have striations on the underside of the head." Mouthparts
often act as sonifiers: "Corixa americana rubs its front legs
against the proboscis." There are clicking mechanisms on the underside
of thorax, files under the prothorax rubbed by leg (Siagona, a scarabid).
Ridges on the abdomen can be rubbed by the edge of the wing cover
(in some Scarabidae), or by the femur (Heteroceridae).
The legs are an important tool in stridulation. ("?)Some
log-horned beetles (Prionus) rub hind legs along edges of the elytra.
In a few aquatic insects legs are rubbed against the head Many long-horned
beetles rub the rear edge of one segment of the thorax (usually the
pronotum!) against another. Some Hymenoptera (ants, mutillid wasps)
rub edges of adjacent abdominal segments against one another.
EVEN some larvae stridulate. Larval beetles, as in the Lucanidae,
Passalidae and Geotrupidae, scrape the middle leg against a file surface
on the third leg. In one species, Passalus cornutus, what
was once the third leg has now been reduced to not much more than
a file. ILL Stidulatio is performed by the pupae of some
Lepidoptera, or butterflies.Aside from adventitious, sounds produced
incidental to some body movement, such sonifying is found in ten families
LEPIDOPTERAN LARVAE?? (Hesperiidae, Papilionidae, Lymantriidae and
Saturniidae, which rub ridges of one abdominal segment against another.
The larva of the Epiophlebia (Odonata) rubs ridges on the abdomen
by ridges on the hind femur.
Stridualtion is found even among ants: Ponerinae, Dorylinae am\nd
primitive Myrmicinae use edges of the gaster and the petiole as a
scraper and file set. Among true flies, or Diptera, the Tephritidae
stridulates by vibrating the cubito-anal, or "armpit", section of
the wing across rows of bristles on the third abdominal segment.
Another mechanism produces sound by vibrating a tymbal which is tight,
elastic membran. Cicadas create their loud buzzing through tymbalic
TAPPING Termite soldiers thump their heads against the ground. The
death watch beetle Anobium thumps its head on the side of
its burrow. Certain grasshoppers tap their feet on the ground, and
some cockroaches hit the ground with the tip of their abdomens.
AIR PIPING The mammalian source of sound, the
modulation of air stream is also used by insects for the same
purpose. Of the few examples known are the May beetle and the bowfly
which expel air through spiracles.
WING AS SONIFIER
VIBRATION
And now we consider
the wings in their sound making function.
In communication th wings emit
a humming or buzzing sound, either while
flying or stationary, which their conspecifics recognize. The
Scarabidae, the Orthoptera, the Heteroptera, the Diptera and the Hymenoptera
almost always produce a tone audible to humans. (Frost p. 201) Other
vibrations may surpass the
high range limit of human hearing. /Wing vibration is known to be
a sexual identifier, especially in mosquitoes
(DO!) I DIDN'T WRITE DOWN THESE EXAMPLES!
Curiously enough sometimes the thorax is involved:
a bumble bee with wings held will still emit a buzz by means of some
vibration inside the thorax. One can presume the vibrating wing muscles
to be the sources of this sound.
The wings
can also serve in STRIDULATION. The
common grasshopper sound, that of the short-horned
grasshoppers, comes from rapidly moving
the row of tiny pegs on the inner side of the hind femur against a
hard ridge alongside the front wing. Others families(?) scrape wings
together while hovering. Long-horn katydids produce vibrations
through an elastic membrane, the tympanum,
part ??? the base of the right front wing. The crickets, of course,
create their powerful sound as they rub together the special sound
producing bases of their front wings.
Since we are talking of wings with raspy surfaces, could we not reduce
these wings to the size of the paranotal lobes and still have them
perform something? Perhaps not, since they would extend /jut out from
the body and where it would be inconvenient for a leg to reach it.
Howvere, if the lobe was forther decreased until it was only an irregularity,
a barely noticeable ridge on the surface of the thorax, then, we would
find an analogue of elytro-femoral stridulation, where the proto-lobe,
diminutive as it was, would be oxypragmatic because it could perform
an adaptive function. It is important to note the other part of this
stridulation, the femoral pegs or serration and the appropriate leg
movement would have to be already functional. They might be teamed
up with some stridulatory sections on the abdomen. However, the term
"immediacy" need not necessily mean a near-simultaneity. If the proto-lobe
had survived a minimal number of generations, and if at that time
a femoral movement appropriate for stridulation had also developed,
perhaps as a visual signal, then the two when adventitiously combined,
would immediately produce a new function.
4.4 FINDING STRIDULATION AS OXYPRAGMA FOR
"LOBE" - so lobe of Accepted Theory still stands, but now has an adaptive
But the mintue proto-lobes could also enlarge to a dgeree. There
were no wings that work in stridulating, and also resonante or amplify
the sound, as with katdids or crickets. If the protolobe developed
into a narrow, somewhat elastic ledge, it could not only stridulate
but amplify as well.
a, it would act as resonating board.
Various ways of possible for stridulation can be imagined. The immobile
but adjacent lobes, could be rubbed against each other, powered by
intersegmental movement, (but this is not as likely as their employment
as edges to be scraped by legs.) See 4.9 below. ILL
10/29/90 ADD: proto wing directed backwards could act a part in as
file/rasp set better than on e irecged perpendicularly to the body.
Such placement of early wings has been advocated by some authors,
because the backward directed wing pads are the only ones found on
fossil and recent nymphs.(Sharov, p. 110-111.)
CRITIQUE OF STRIDULATION TO LOBE THEROY
This theoretical development of a paranotal lobe from stridualtory
surface? actually supports the accepted paranotal theory. Lobes could
indeed have come into existence oxypragmatically as originally small
extensions of the integument. Their development from files or rasping
surfaces into flat lobes could be described. Perhaps some section
of the stridulatory expansions could have evolved into resonating
plates. Or still being immobile expansions but located on adjacent
body segments the emreging lobes could also reub against each other
through segmental movement. This could conceivably even evolove into
the flight mechanism ILL However, these propositions are dependent
on more speculatory conditions, they add to, not subtract from the
unknowns we have started with. and so it is avisable to look for simpler
modes of evolution for them.
VISUAL COMMUNICATION COMPONENTS OF FLIGHT
Today wings perform important visual roles. The colorful optical designs
of Lepidopteran wings serve a vital role in mating, as well as in
defensive mimicry. However, this function is also performed by a secondary
wing development, the elytra of beetles (Coleoptera), so that it is
not so much the flight apparatus, but the exposure of a large visual
area that is significant. The mobility of the wings and the consequent
transformations of visual data adds another source of information.
Wings also increase the visual size of the insect, so that an individual
will be easier to recogniz, and a collection of insects such as a
nuptial swarm will significantly increase its visually reflective
surfaces due to wings.
4.6 POSSIBLE APPEARANCE OF VISUAL ROLE OF LOBES through size
increase as resonator. THIS MAY SAVE THE THEORYGoing back
toprimtive lobes as stridulatiry structures, as mentioned above, it
is plausible that they might increase in size through selection for
modulating or amplifying the sound produced. But in this event at
one point they would also become visual objects. And although the
stridualtory origin of lobes is the start, later, functioning as viual
signals, the lobes could augment their size and develop mobility thorugh
slecti0on for maximum communicating effect bcause a moving object
attracts attention. The stridulatory function would be lost but an
avenue towards flight would open.
ILL THis devlopmetn could give rise to eovlution in size
of lobes-like extensions, and once the structure reaches a
certain size, it wll automatically become oxypragmatic as
a visual object.
<[>4.7. PHILOSOPHICAL NOTE: wings are still used today forvisual
and sound communication -- prehistory survives, cf. concept of birds
as living dinosaurs.]
VISUAL communication by wings today
The a visual role assigned to the wings needs little documena\tationy.
Insect bodies and wings are often beautifully designed in shape and
color and pattern for species identification and for defense.
a) The Odonata, (whose fossils are thought to be(?)) the close to
early flying insects, are a good example. In bright sunlight the large,
reflective wings act like like mirrors.
Url Lanham writes: "In a spacious mountain canyon one may see the
sun glinting on the wings of hundreds of dragonflies, from half a
mile away, as two or three hundred feet high in the air, each patrols
its bit of airspace." (The Insects, Columbia U Press, 1964,
p.185) Their positions at rest strongly support their visual use as
well. At rest true dragonflies, or Anisoptera, hold the wing straight
out in a horizontal position, ILL, while the damselflies,
or Zygoptera hold theirs verticall). It is reasonable to assume that
territorial insects like the dragonflires would present their wings
as teritorial signals and these positions optimal observation angles.
ILL Moreover, the closing and opening of the wings is automatically
a signal function of visual pulsation. Important visual clues are
given in Odonata by various ways of bending the abdomen, and also
by non-flight wing movements, but the wings must also serve in recognition
at a distanmce either when flying or perching.
b) The wings are highly functional visual signallers in other Orders.
For example, Drosophila males exhibit mating displays composed of
body orientation, tapping, wing vibration, wing flicking, wing waving,
wing semaphoring, wing scissoring, leg vibration, leg rubbing, circling,
licking, and finally mounting. (H. T. Spieth, Courtship behavior in
by M.D. Atkins in Introduction to Insect Behavior, Macmillan,
1980, p.112) Evidently wings possess effectivevisual function
and no doubt wings, offering both large visual areas and reflective
surfaces, whether movable or not must have possessed a meaningful
role in insect behavior preceding flight. The functions of light reflection,
or dynamic wing motions are subject to selection and thus the wings
will tend to develops selectively for structural strength and size
of surface area.
Physiological derivation of wings. -- TO BE PLACED SOMEWHERE
1. Structure of wing, sacklike, ill. and its attachment to
and articulation by two different sclerites makes its up-and-down
movement possible. This motion is sufficient for sonification, and
as soon as the pre-wing surface area increases enough so that the
surface-to-mass ratio permits it, the sonic function of buzzing
becomes polypragmatic: vertical lift automatically becomes possible.
Lift necessitates another factor to be present -- through some asymmetry
of motion -- either in intensity, speed. It is not necessarily
N E W : 10-15 The stridualtion oxypragma for LOBES
At this point we can evaluate the hypothesis of the proto-lobe which
through stridulatiry oxypragma could also become a visual organ. Once
the lobes have reached a visual applicability a mechanism to move
them would greatly enhance their effectiveness, unfortunately the
emergence of such mechanism has no factual underpinnings. A close
co-evolution between the sonifying and visual functiuons of the lobes
is acceptable, yet the emergence of\ either function alone is no better
documented here than in the paranotal lobe theory.
In conclusion, wings and wing-moving mechanism are not categorically
derivable from paranotal lobes. Finding an oxypragma and consequent
early devlopmental path for the paranotal lobes only supports the
accepted theory.
O L D : 5.0 NARRATION LEADING TO THE NEW THEORY -- 10 - 5
How does the flight mechanism work, anyway? Mb. some
useful infornation can be found there.
T H I s IS THE REMAINDER OF IT AFTER CUTTING on 10-15 Mon:
CLICK MECHANISM w. ILL, saying: for the action to continue
pnly triggering by energy input is needed, other wise it just clicks
The flight action in Sarcophaga (Diptera) (R. G. Davies. Outlines
of Entomology, Chapman and Hill, 7th ed. 1988, p.26) employs a click
mechanism whereby the wing goes into a lower position and stays there
until it is triggered into the high position. This action is clearly
describable as a bi-stable, or two-state vibrator. What enables an
insect to possess such a mechanism? The nature of the materials involved.
The substance of the insect integument is elastic to a point where
it can be flattened into thin, flexible sheets, and then can act like
springs. When this elastic material is bent and held, upon release
it will spring back to its natural position. Any number of tension
and escape mechanism are utilized by humans to achieve effects. The
bow and arrow(?) is one, the clock, with its escape mechanism, locks,
ball-point pen buttons are just three examples.
5.12 Well we can here make a propostion: The flying mechanism was
inside the thorax of the insect, functioning as a sonifier, and the
audio output, the vibration came from ssome part of the integument.
In general insects are not sensitive to pitch, but volunme or intensity
is recognized by them so any factor affecting intensity would be selctable.
VIbration is not even necessary: the production of a slowly repeating
click pulse would be influenced by a new structural member of the
transducing surface.
VISUAL: NOw we come to another case of oxyprgama. As soon as the proto-lobe
or lobe reached a certain size and so entered the liomits of insectan
visual perception, it coul, especially, if moving, function as an
effective visual signaller>> In this role the lobe would be sleected
in a competition for increased visual output. LANHAM HERE!!! - - -
Perhaps before the existence of the vibrating thorax and the lobe
some insects had visual patterns, colored patches or bright shining
surface on the thorax. WHen sound producing structures appeared ,
thiese spots might pulsate, move slightly in the visual field. There
will be more top support this idea later.
5.17 In effect, the sound production and the visual siganlling developed
simultaneously, in close correlation within the limits defined by
their share of developmental requirements. Each one benefitted its
output if the lobes's surface area or surface reflectivity/smoothness
increased. But the visual function tended to decrease and so was in
some part selected out in favor of sound or flight>>
5.19 As for the argument that the phylogenetically primitive fliers,
the Odonata have no click mechanism (MS p. 11) THEY most liekly
DO! Orthoptera ceratinly do have it! see:...? They are probably not
primitive either!
BRIEF STATEMENT OF THE PROPOSED THEORY here, and chart of same. FULL
SUMMARY COMES AT END OF SECTION<< just before supporting facts
. . . Supposable shapes of lobe, and its oxypragma, etc.
N E W NARRATION LEADING TO KEY 10-15 Mon
Having found no satisfactory answer to our inquiry, it is time to
examine one system so far not explored, the flight mechanism itself,
which has been briefly described on p. 000.
As mentioned earlier the mechanism of flight has not one but three
muscular systems, the direct, the indirect and the accessory ?indirect?
flight muscles. The direct and accessory musculature is evidently
tied to flying in a straightforward manner, but the indirect mode
is a step removed and perhaps it is worth considering especially
that reason.
THE INDIRECT FLIGHT MECHANISM
Two sets of muscles are employed. The dorsoventrals, connecting the
tergum and sternum vertically compresses the thorax. The dorso-longitudinals,
running from the anterior to the posterior phragmata, exert a longitudinal
compression. Each of these two actions alternately deforms the thorax
in the vertical and the horizontal direction respectively, as if it
were an elastic box. Because the wing is attached to the box as a
lever, it performs and up and down motion. ILL The action is termed
indirect bcause the muscles do not directly affect the wings, instead
the wings move as a result of translating the thoracic deformation.
The actual process is actually somewhat more complicated, but the
essentials are covered by the above description.
There is however an intersting aspect to the indirect flight mechanism
discovered while studying wing movement in flies. It was found that
here, before its action eaches the wings the thoracic deformation
is first routed through an extra mechanism. Its description is best
presented diagrammatically. The alternating forces on the thorax affect
a small system composed of elastic materials and sclerites. This system
locks the movement in one position until opposing muscular force causes
it to lock into the other position. ILL This system is called a click
mchanism since with musckluar drive provided, it will click from one
state into another.
Another way of defining it is a bistable vibrator, where the mechanical
parts continually switch from one position to the other. In the case
of the fly Sarcophaga, where this mechanism was first discovered,
the system also possesses an imtermediate unstable position. The muscles
merely move the mechanism from the first stable to unstable position,
from which it quickly reaches the second bistable position. This means
that the muscles need to exert themselves minimally, the main energy
is resident in the elastic, energy-stroing properties of the thorax
and the click mechanism. The mechanism itself is directly attached
to the wing base, and so the three positions produce the up, level
and down positions of the wing. The speed of vibratiuon is clearly
demonstrated by the wing beat of the fly. ILL
We are meeting here with a mechanical vibrator, entirely analogous
to an electronic oscillator or multivibrator. A basic description
of this mechanism, in fact, states: "<[>t]he existence of these elastic
forces in the wing suspension, considered together with the fact that
the wings have appreciable inertia, shows that the system must becahve
as a resonant mechanical oscillator." (J.W.S. Pringle, ...Locomotion:Flight,
FINDING THE KEY
There are two systems at work here, the wings and flight motor, each
dependent on the other to effect flight. Neither one alone can produce
flight. What could each achieve without the other?
1. Lobes wihtout motor = returns us to an erqlier stage, where the
apranotal lobe is without any apparent use.
2. Motor without lobes/wings = just a vibrating mechanism unable to
exert action on aerodynamic agents necessary of flying.
(little TABLE here)?
Still, a vibrator does do something. It vibrates without any connection
to other structures. And we may at this time recall a fact mentioned
earlier under insect sonification: "The wings movements of most insects
produce a humming or buzzing siound, but in some insects the thorax
is also involved in the production of sound; a bumblee bee held by
the wings will still buzz." (Borror, Introduction ot the Study of
This is an important observation. A vibrating mechanism, without
any relation to another object can produce sound. We have found the
This realization opens a new direction for inquiry. If the thoracic
vibrator without wings is a sound producing structure then its possible
presence in pre-flight insects needs no justification. It would be
part of the assemblage of insectan sonifying equipment and would have
an adaptive function long before the emergence of flight. Accepting
such a proposal requires us only to look back and once more note how
fundamental sound is in insect behavior. Making sound is a relatively
simple engineering objective, especially when compared to flying,
therefore we can assume with relative comfidence that sonifying was
well established and diversified by the time protowings would appear
for the first time. NEXT PARAGRAPHs ARE OLD -- FIX!
There are several facts to support such a view, to be discussed below,
but at this time we can just state that presumption of the existence
of a vibrating sound producer in the thorax also offers the paranotal
lobe an oxypragmatic function, or immediate applicability
at a most primitive stage in its development. If some part of the
thoracic pleuron is involved in resonating with or transmitting this
vibration to the outside, or if the section of the pleuron itself
is a vibrating memrane, then a visually and aerodynamically insignificant,
minor structural alteration has a chance to modify the vibration.
/NEW HERE 10/28 HAVE TO: clarify that because of this new sonic idea,ther
are two possible sources of proto-wing. One is the paranotum, the
other is a structure growing on the sonic membrane. As we shall see
later, this supplies the answer to how the proto-wing became hinged
at one time./
Here we find ourselves fortunate as well, in that we can clarify
the ontogeny of the paranotal lobe. An adventitious variation in density
or dimension such thickening, sclerotization, folding, or evagination
at a pleural location, either itself vibrating or connected with vibrating
surfaces, would tend to alter the frequency or other acoustic component
of the sound and so enter a course of selection, eventually evolving
into a paranotal lobe. This structural development would have had
adaptive significance from its earliest appaearnce and therfore would
have been oxypragmatic. What brings about the oxypragma is partly
the fact that the acoustic character of a relatively thin vibrating
plate can be affected by relatively minimally sized particles of matter.
But the transformation of a relatively small, near-invisible structural
addition that possessed acoustic effect would lead to an additional
devlopments. The proto-lobe, associated with a vibrating memrane would
in itself tend to increase in surface area and optimize in structrual
and elastic characteristics to increase the amplitude of the sound.
Thus it would enter the range of visibility. And since it possessed
a kinetic component it would not only be visible but would attract
attention by virtue of its motion. It is impossible to know the vibration
rates of our hypothetical thoracic sonifier, but it could have had
a variable rate in which case the motion of the lobe would at times
be slow enough to create maximal visual impression. Even if the rate
would not be variable, the onset and the end of the vibration pulse
would offer a contrast between the moving and stationary phases of
the visual object. In addtion, it should be noted that we are dealing
now with a combined audio and visual function and the two would strongly
tend to reinforce each other's effects. At any rate, the original
sonifier would at this point enter a relationship and a combinative
selective process wherein the two components at times might reinforce,
at other times might compete with each other.
TO FLIGHT:
It is impossible to speculate on the actual position and orientation
of this hypothetical lobe. It may have been lateral and more or less
perpendicular to the ground or it may have been postero-lateral, bent
backwards as wings are today in all flying orders except ODonata and
Ephemero<[>tera. Whether the lobes could be folded, like modern wings,
is an uncertain point, but had the pre-flight lobes been large enough
they most liekyl would tend to be employed in nuptial display, playing
out sets of movements that may have included flexing.
We also do not know what angle the lobes fromed with the body. If
the original angle was parpendicular to the pleuron, their movemevt
may have been up and down, like that of mdern wings, and in that
case a simple vertical movemnt of the lobe attended by some assymetry
between either the up-and-down forces, or between the sizes of the
lobes, or a factor due to an existing wing-flexing ability, in combnination
with an appropriate lobe vibration rate, an appropriate body weight
and lobe surface ratio, and the influence of air movement would one
day automatically produce FLIGHT.
At this point our statement is a general one, but there are additional
corroborating facts which will offer a plausible basis for the hypothesis.
To summarize what has been said so far:
1. Pre-flight insects employed sound communication.
2. One of these sonifying mechanisms was a thoracic buzzer or vibrator
which had de- veloped from the elastic properties and the existing
musculature of the thorax.
3. A integumental structure appearing in association with the vibrating
area (perhaps a membrane) functioned as a modifier of the sound.
4. This structure, the proto-lobe, also took on visual functions and
increased in size.
5. The sonic and visual functions tended to select the proto-lobe
into a flat and strong
expansion.
6. Since the mechanism of movement was already present and acting
on the lobes, an automatic, adventitious occurrence of lift
and flight gained significant likelihood.
Argument: Odonata have no click mechanism
But what if someone says: the so-called primitive fliers, The
Odonata and Orthoptera?? have no click mechanism. The answer is that
they do possess it in a less intense form: they have a stable
afulemule felemeli; felemelem a fulemulem; alaptalan tapasztalatalapaim;
nd less stable positions of wing. Their wing structure is "semi-bistable."
ILL We can quote J.W.S. Pringle (Chapter 7 Locomotion, p. 435 ...):
"Partly because of ...<[>the] elastic cuticle at the hinges and partly
because of the general elasticity of the solid cuticle and muscle,
movement of the wings is influenced by elastic forces. Sometimes,
as in the mesothorax of Schistocerca, the wings assume a fully down
position when the main flight muscles are relaxed; sometimes, as in
Sphingidae and Anisoptera (Odonata), the stable position is horizontal."
THE GT SOURCE OF THORACIC SONIFYING: -- still to be worked out
in detail!
(To meet the requirement of relying only in documented substratum
(source) for a proposed sequence of events: ) The physical properties
of the cuticular materials and the presence of thoracic and leg musculature
only need a novel set of neurological stimuli to appear. There is
1. Wing muscles are partly identical or derivable with leg muscles
- used originally for audio or visual communications -- The legs themselves
may have been the signallers; lobes may have appeared to amplify this
visual leg action; this could have had audio side-products.
2. Indirect wing muscles are derived
3. derivation from breathing musculature
This may come here or as an appendix (or maybe
simpler here, more technical in Appendix.)
STUPID: Remember to learn terms properly: tegmina=, terga=,
SUPPORTING FACTS
1. SURVIVAL OF ORGAN AND FUNCTION The most generally supportive
fact is the obvious functioning of the wings
anf flight mechanism as sound and visual communicators. We may be
seeing the continual survival of the bsic function to which the new
one of flight was grafted. Analogous occurrences can be found: YEAH??
2. WINGLESS THORACIC
BUZZ The thoracic buzzing in present in the bumble bee shows that
the flight musculature is capable of buzzing
independently of the wings. This may be circular reasoning, and perhaps
the buzzing ability of the flight muscles is merely a
by-product of flight, however the likelihood
that a thoracic vibrator existed prior to flight offers the simpler
and more likely explanation. Formerly
bee-piping was thought to be produced by air forced through a spiracle,
but now it is thought that "the sound is probably produced by vibration
of the thoracic scelrites and so may be regarded as a vibrating membrane
mechanism." This statement supports our suggestiuon that the thoracic
pleruon is a likely sight for sound production because of its structural
qualities and components.
The matter of thoracic vibration can also be related to the click
mechanism. We read that : "...a click action...may also be effective,
when the wings are folded, for production of sound or in pre-flight
warming." (Pringle, Locomotion: FLight, p. 436)
3. THE VIBRATOR NATURE OF THE WING MECHANISM
A quote we have already seen expresses the potential
sound producing properties of the wing-mover system in the thorax
is expressed by the statemen: "The existence of these elastic forces
in the wing suspension, considered together with the fact that the
wings have appreciable inertia, show that the system must behave
as a resonant mechanical oscillator." (Pringle, Locomtion:Flight,
4. Ancient symmetrical wing venation
Pterygotes have wings with asymmetrical venation, favoring a placement
of main vein trunks at the anterior margin of the wings ofr aerodynamic
purposes. However, one of the early winged inscts, the Paleozoic cockroaches
show wings with symmetrical vein distribution. One author, Sharov
thinks this venation is a regression caused by the development of
concealment-oriented behavior. He also stresses the close resemblance
between veins on theses wings and veins in leaves found in association.
This would indicate a tendency toward mimicry. (Sharov, p. 114)
However, we might question that with the limited abilities of sight
in contemporary predators such mimicry would have developed at that
time. The concealment behavior might also be doubted on the same basis.
Nevertheless, the symmetrical venation of these wings definitely indicates
a primitivity in flight, and can easily be explained as being retentive
features of the sonic and visual source of wings.
5. High plants
But still, the same synchrony can also be interpreted in favor of
our postulations. High vegetatio would greatly decrease visibility
for insects and therefore mating or other interests of insects with
evolving sonic-visual protowings would tend to gain from proto-wing
vibrating or flapping, or maybe fluttering in order to be seen. Or
maybe coming of high plants could have been a strong triggering force
in selecting from mere flutterers or vertical risers, because to fly
up to a plant the insect also needed a minumum of flight control to
land its feet on the chosen part of a plant, which may be have been
at at an angle. Such condition would support the alternate theory.
MB NOT CORRECT: The high plants would also have an effect indirectly
related to size. It may be correctly presumed that the smaller the
vibrating insect, the more needed would be the ability to fluuter
up but because of its size in relation to distance. etc ??
6. Cycada tymbals
The nature of the sonifying tymbal mechanism of cicadas (Cicadidae)
offer information which in more than one way supports and augments
our general argument. The basic tymbal mechanism ILL consists of a
membrane framed by a slerotized rim with a muscle attached to the
membrane at its center. There may be associated resonant air chambers
and aditional smaller muscles attached to the membrane near the rim.
Since the membrane is taut and is outwardly convex, if the muscle
pulls it in and then relaxes, the membrane will spring back to its
normal position. As we all know the sound produced is powerful and
this fact attetsts to the efficient acoustic mechanics inherent in
the insect cuticle. The resonating material is strong, thin. Elasticity
enables it to store muscle produced energy that can be released quickly.
Here we can see that the material requirements of the tymbal are the
same as that of the wing. We also notice that the elastic quality
essetntial in the tymbal mechanism is also essential in the click
mechanism. There is thereofre, an remarkable agreement -- perhaps
homology or even identity?
The tymbal is a monostable vibrator with only one stable position.
The click mechanism has two stable positions. Considering the number
of sclerites in the click articulation we can easily note that by
combining two tymba mechanisms, thereby adding to the number of components,
a bistable vibrator could be fashioned. ILL It can be demonstarted
that alterations to the structure of the membrane can effectively
even make several tymbals out of one: "In Abricta and Magicidae
/(cicadas?) the strongly-developed ribs of the tymbal buckle separately
during the 'in' movement, so that each muscle contradction preoduces
Indeed, the fact that in the cicada's sound mechanism the sound producing
tymbals and the sound sensing tympana are directly adjacentmay reflect
that the thorax is already occupied and both work on the basis of
the acoustic properties of cuticular membrane not only suggests a
shared ontogeny, but also suggests that insectan construction almost
treats the tymbals as modules that can be wired in different ways..
FIX at the end of Tymbal support:
6.1 THE MODEL ANALOGY BTW TYMBAL AND WING
The scematic diagram of the tymbal mechanism shows a frame surrounding
a membrane with an attached muscle. This muscle sets and maintains
the vibration in motion. The auxilliary muscles attached near the
rim control the tension of the membrane and therefore control the
volume of the vibration. The diagram of the wing bearing thorax also
presents a frame, which is formed by the hard dorsum, sternum and
pleuron. The unsclerotized area is the membanewhere the wing is hinged.
The... The two types of muscles in the tymbal are analogous to
the the direct and accessory muscles of the wing. TO BE FINISHED!!
6.2 ADDITIOHAL FACTS IN CORRELATING TYMBAL WITH FLIGHT MECHANISM:
Analogy of small muscles as modulators
The tymbal is activated by a main muscle which is responsible for
the basic vibration, but the curvature of the tymbal is modulated
by a number of smaller muscles attached to the edges of the membrane.
"These muscles, according to Pringle's work on Cicadas, serve
to increase the curvature of the tymbals and in this way increase
the volume of sound..." (Haskell p.52). We may see here an analogy
with the muscles of the wing, where the direct muscle is responsible
for the main upward movement and the acessory muscles modulate this
movement by bending the wing.
Distribution of tymbals
Tymbal organs are not limited to the cicadas and realted families?
(Homoptera), but also can be found among the true bugs, in the Pentomidae
(Heteroptera) and among butterflies and moths (Lepidoptera). we read
that certain mechanisms which have been termed 'tymbal organs" "are
widely distributed. .FIX
Tymbals on lateral surface - Analogy betwen abdomen and thorax
The tymbal organs of the cicada occur on the dorso-lateral surface
of the first abdominal segment. This lateral placement is analogous
to that of the wing articulation. In fact, tymbal membranes can be
found on the dorso-lateral surfaces of the fused first and second
thoracic? terga in Petatomidae. (What about all that bottom placement
talked about??)
Tymbals on thorax
It is helpful to find that tymbals organs can turn up on the thorax,
as well. We read that certain mechanisms which have been termed 'tymbal
"organs" "are widely distributed amongst the Lepidoptera. The organ
situated in the thorax of certain Arctiidae and Syntomidae, is a modification
of the metepisternal sclerite, which forms a membraneous covering
over a cavity. This membrane, the tymbal, is said to be vibrating
by rapid alterations of the shape of the cavity, probably brought
about by contractions of the dorso-ventral flight muscl The
noise produced by the insect when on the wing is a crackling sound,
and in certain genera, such as Setina, is said to be audible over
considerable distances." (Haskell. p. 54,)
Dorsoventral muscles
Aide from the above case of Lepidotera, dorsoventral muscles contracting
the tymbals have also been reported in the Pentatomidae (Heteroptera).
Here the vibrating system is built on the episternum, a location connected
to wing articulation, where a sclerite is devleoped into a vibrating
membrane, the action of which is caused by indirect dorso-verntral
muscles, the main agents of flight. We see, then, an existing
structure that is very close to the model proposed by us for the orgigin
of wings and its mechanism. The fact that the dorsoventral muscles
are capable of producing tymbalic vibration emphasizes that such action
and structure could have occurred in a hypothetical thoracic tymbal
Thoracic tymbal activated by thoracic deformation
To illustrate such a propostition we can cite a case of a tymbal organ
on the thorax, powered by thoracic deformation! The tymbal cavity
of the Arctiidae and Syntomidae mentioned above is described as being
deformed by the dorsoventral muscles.
Possible origins of ancestral lobe/wing as part of tymbalic
Tymbal membranes are often covered by a scleoritzed plate. Such an
extension over a resonanting cavity may suggest yet another variation
for a theoretical origin of the paranotal lobe: instead of being the
vibrating part, it may have developed as an accessory structure to
the tymbal. We have mentioned the ide that lobes may have originally
appeared as minute structures modifyng or amplifying the sound. It
might be asked that if cicadas cna oriduce intense sound with the
unadorned membranes, what need would be there for amplifying it. An
answer may lie in the fact we can find tymbal organs that produce
low amplitude sounds. In many Auchenorrhynchan families (Dlphacidae,
Cixiidae, Cercopidae, Membracidae, Cicellidae) hte "sounds produced
by these insects are always of low intensity and not always audible
Synchrony of tymbals
The studies on cicadas show that in the typical case the two tymbals,
on opposite sides of the body, work synchronously. This characteristic
is in perfect accordance with the synchronicity of the wings on each
side. Although in some cicadas (Magicida and Fidicina) the opposite
tymbals are not in phase -- a fact that may or may not be significant
in our discussion -- such indepence may be due to an ability to control
the muscles involved. This kind of control is basic in flight action.
The range of tymbalic vibration rate encompasses wing beat rates
It is noteworthy that the cicadan tymbal vibrates naturally at 4500
Hz, a rate rather over the rate of insectan wing beat in general.
The high end of wing beat frequency is somewhat over 1000 Hz, presenting
no problem in matching the sound producing vibration rates to those
of wing beats. Carpocoris (Pentatomidae) has a wing beat rate of 150-200
Hz, somewhere in the middle of the entire the range of wing frequencies
ranging from 8-12 Hz to over 1000 Hz. The extension by wings is known
to reduce the basic vibration rate ot the click mechanism because
of its own inertia and air resistance.
The fact that the frequency range of tymbalic oscillation is considerably
higher than frequency of oscillation needed in wing movement clearly
enables the tymbalic vibration system to provide an efficient source
of flight movement wihtout additional development. The only possible
requirement for the vibratory mechanism may be the acquisition of
sufficient power. With the availability of the thorax, the structure
of which would already possess more tighly integrated segments, and
a more sclerotized pleuron to give leg movement a more stable base,
such additional power may have been accessible to a thoracic vibrator.
Tymbal action by direct wing muscle
There is at least one known instance where a direct flight muscle
operates a tymbal. Concerning the tymbal organs in some Arctiidae
(Lepidoptera) we read (Chapman/ Sound production, p. 694.) that not
only is the location of this tymbal on the side of the meta- thorax,
but that its "main effector muscle is the coxo-basalar muscle". This
fact illustrates another homology between the flight mechanism and
the proposed ancestral thoracic vibrator.
Association between tymbal and tympanal organs
Tympanal organs of sound reception are structurally close to the sound
producing tymba. Both basically are built on the elastic nature of
the cuticle. In one case this membrane vibrates due to direct muscluar
action, in the other it vibrates due to incoming air vibrations. The
two even share the muscle component. Among the locusts the tympanal
organ possesses a tensor muscle attached to the membrane to control
its tension. Perhaps this counters the effects on the membrane by
atmospheric humidity and temperature.
The tympanal organs, as in the cicadas, are directly adjacent to the
tymbals. Here we may be seeing a modular nature of membrane and associated
structures. Depending on the requiremnents, a membrane module may
be an emitter or receiver of vibrations. The contiguity of these two
functions and structures in the first abdominal segment of the cicada
may represent an ancestrally deviating specialization of a battery
of membrane modules.
Wings associated with tymbal membrane
There is an example of close association of flight structures and
tymba membranes, long-horn grasshoppers possess a tympanum as "part
of the base of the right front wing. When the bases of the wings are
shuffled rapidly together, a file on the base of the left wing sets
the tympanum vibrating." (Lanham, The Insects, p.148-149.) This might
be a secondary development where the membranous quality of the wing
and its ability to vibrate are recombined, still although the mambrane
is vibrated by files on the wing, these files only trnasmit a vibratory
acttion originating in the wings, so that we are basically left with
the wing acting as both the membrane and its actuator.
Summary of comparing cicada tymbal and flight
The above review of comparing the flight and the tymbalic systems
attempts to show the strong parallels between the two, both in structure
and function. And if, as reason would suggest, sound production preceded
flight, then such parallelism supports the proposition that flight
is a derivative of some type of sonic vibration mechanism on the thorax.
(TABLE OF COMPARATIVE CORRELTAIONS BTW WING AND TYMBAL AND MODELS
SHOULD BE IN APPENDIX!) -- OR HERE ??
SUPPORT:GLIDING OR FLIGHT MAY NOT HAVE BEEN ORIGINAL FUNCTION
The classical image of the insect with the original paranotal lobes
is the fossil Palaeodictyoptera. The orientation of its lobes is exactly
as wings on an airplane. However, certain Paleozoic nypmhs, like those
of the Upper Carboniferous Palaeodictyoptera, Blattodeae and "(Protorthpetra?)"
exhibit wing pads lobes that slant postero-laterally. ILL This "position
of wing pads...lends wieght to Sharov's proposal that insect wings
were at first posterolaterally directed; but they may have been flexible
enough at the base to allow promotion to the perpendicular position
in flight." (R. J. Wooton, Thefossil record... p.250) If in fact the
wings at first were thus positioned, this may indicate that the wings
originally had been lobes that clicked or buzzed and waved or flashed
and would not necessarily have been positioned in any way proper for
flight. A lobe set perpendicularly to the body is minimally visible
when facing the insect, but maximally visible when facing the sinsects
side, but the angle of a backward directed fan-like protowing igives
maximal noticeability fro all angles. ILL
Mechano-acoustic properites of the insect cuticle
Assigning sound production such a basic role in insects, even leading
to the evolution of flight, is not an exaggeration when the physcial
nature of the integument is considered. "Jensen and Weis-Fogh, 1962)
give some figures for the mechanical properties of the two types of
cuticle found in the locust. The solid tanned cuticle from the thorax,
legs, and wings is similar in its mechanical properties, with a coefficient
of elasticity of 800-1000 kg mm-2, and a tensile strength
of 8-10 kg mm-2 for an elongation 2-3%; these are comparable
to the values for oak wood" (Pringle, Locomtion: Flight p.436)
To vibrate under minimal influence, a material object needs to be
of relatively minimal mass and diameter, so that membraneous or frictional
sound making by insects is quite natural due to their size. Structural
details therefore need and can be small and because the hard material
of insectan structure is thin and elastic, it is likely that insecst
will broadly develop sound making. The analogy to oak only illustartes
how humans , building muscial instruments also rely on a material
nd elastic character of6.
The hinged articulation of the wing to the notum itt tartok
kb.
Write: how the paanotum may not have been the ancestor of the wing.
IT could also have beeen a membranous fold growing out of the pleural
surface covering the basalr, subalar, etc?, the pleural wing/leg muscle
slcerites. ILL Maybe this was originally a band connecting
the several separate sclerites which may have together with axilliaries
acted as membranes subvibrators, in order to unify the sound for amplificarion??
amd then ot satarted making a differnet nouse bk of the drum pulser
turning into a fan pulser (see below in *** NEW)
Anyway, this is the possible reason for the fatc that the
wing is only hinged to the notum. And so answers the question of how
the protolobe ancestor of the wing became hinged.
in the sound of a tymbal versus a tymbal with a wing lobe coming out?
I mean because first the membrane pulses at you as roughly a circle,
but the second one pushes different waves at listener. I think there
probably is a differnec in the sound of such items!b Easy to check?
THE EMPTY THORAX
Today the thorax of Pterygota (flying insects) is filled with flight
muscles. "The remaining organs have shrunk to 15 per cent of the space
at a generous estimate, leaving at least 85 per cent of the total
available space to be taken up by the flight muscles." (W. Nachtigall,
... p. 68) Before flight the thorax contained only the muscles moving
the segments and controlling the coxa, or uppermost segment of the
leg, so obviously the thorax possessed latent potentials. Compared
with other body parts the volume of space potentially available to
the thoracic mass was relatively undeveloped before flight -- even
today the thorax is generally smaller than the abdomen. Therefore
thorax had capacity for additional musculature and integumental extensions.
Put another way, by self-definition today, the thorax is capable of
holding both the leg and the wing musculature, therefore when it had
only the segmental and coxal musculature, the thorax was utilizing
only small percent of its potentials. The abdomen was already specializing
in other functions, so the thorax, equipped with the surface-locomotive
(and perhaps the respiratory) neuro-muscular mechanism, had an appreciable
likelihood to be employed in additional functions such as sonification.
Nature would have been exceptional had it not utilized available opportunities
to construct. Because the sclerotized, hardened parts of the integument
are bounded or bridged by more flexible cuticular materials, there
is possibility to fold or bend these sclerites relative to each other.
These conditions create a potential for the reflective and elastic
properties of these materials, combined with muscular action, to be
selected for a role in visual and sound communication.
It is certain that a significant percent of the musculature is shared
by flight and the coxopleural, or leg base muscles, which existed
before flight, but it is also true that flight shares muscles with
another older set, the dorsoventral and dorso-longitudinal muscles
of the thorax. These muscles are agents segmental and perhaps respiratory
movement in the crawling ancestros of insects. Considering that much
of the flight musclurature is not exclusive to flight and that this
musculature is also not merely potentially but actually applicable
to producing sound, we can present one more fact to support the possible
sonific origins of flight.
The thorax as visual field
We had earlier stressed the importance of visual communication in
insects. Today the wings and the abdomen are primary sites for visual
exhibit. In the pre-flight period the wings were absent thereofre
the bare thorax would be have been a strong candiate for carrying
visual information. (By controlling the wings, the present pterygote
thorax, in fact, plays a part in visual kinetic communication.) In
present-day flying insects the thorax is longitudinally compressed,
a dsegin dictated by the engineering of walking and flight, but before
flight it may very well have been closer to its full primitive, primary
size. By adding the thorax to the abdomen, a total visual area increases
by a large percentage and such stretch of valuable advertising surface
would hardly be neglected by the rules of natural design. We can imagine
wingless Paleozoic insects with an expanse of color, spots, patches,
stripes, bands, geometric or abstract patterns stretching from the
thorax to the end of the abdomen.
Here we can pick up the accepted theory of flight and ask wether
the paranotal lobe was perhaps a visual object? Might it had distinguished
various species by its size, color, transparency or reflectivity?
The Stenodictya had wings also and presumably could fly. It
would therefore have reason to be seen from above by rivals or mates
-- such activity can be found in modern Odonata. The dragonflies,
wether perching with wings held horizontal or vertical, seem to be
adverstising their presence to others. The high reflectivity of their
wings most certainly is not lost on the eyes of their conspecifics.
In fact the horizontal nad vertical wing position can be shown to
offer maximum visibility when considering all possible viewing angles..
See appendix for more.
Visual design in communicating can also be three-dimensional and moveable
-- like the modern wings and elytras. There must have been a time
when wings and flight was still primitive, but when its commicative
ability was widely employed. An early flier, fluttering the wings
in a certain pattern would almost certainly be also identifying itself
to a mate or rival: the expressiveness of kinetic display would be
rather likely to create a strong, selectable impressivity.
Potentials in functional sclerotization of thorax Maybe to
The development of sclerites and associated muscles to transform
a vibrating membrane structure into the wing and flight structure
is of course not an implauible proposal. Similar structural developments
are the basis for most insectan faculties. We read that "...the development
of refined interrelations between muscles and sclerites has been the
principal line of evolution in the arthropods." (Snodgrass, Principals
of Insect Morphology, p. 53) Whereas in the Peripatus, an arthropod
close to the ancestral insect stock, or in the soft bodied modern
larvae there is minimal sclerotization, at the other extreme of insect
specialization the pleuron of the burrowing centipede, the chilopod
Haplophilus subterraneus, is almost totally covered by sclerites
acting as body armor against the crushing pressure encountered in
burrowing. ILL (S. A. Manton, The Arthropoda, p.378)
Sound making potentials of the thorax
The thoracic and abdominal terga and sterna, or top and bottom slcerotized
plates, are separated by the pleuron, or membraneous cuticle. ILL
Therefore the pleuron can be thought of as a membrane stretched on
a frame. Being so, with minor dimensional alterations and with sufficient
muscluar or neural effects supplied this membrane, stretched between
the hard plates is readily adaptable to producing or sensing air vibrations.
At the present the abdomen and the thorax are utilized by insects
for tymbal function, but the thorax of a pre-flight insect could perhaps
have claimed more potential in sound making than the abdomen because
it also contained the coxopleural muscles belonging to a specialized
and rhythmically refined neuromuscular system, walking. With such
potentials the thorax may have had a good chance developing a dominant
role in sound production.
The significance of certain leg muscles doubling as direct flight
muscles is that the pre-flight leg muscles could have easily performed
sound making without essential changes in leg-operating position and
action. The fossil records documnets the existence of thoracic legs
prior to flight and sonification is likely share this chronological
trait, as well, so the cooperation of the two in sonification is not
implausible.
THE EQUALITY OF LEG AND FLIGHT MUSCLES is not new! Wooton,
p. 250: the thoracic paranota ..."developed the ability slightly to
pronate, supinate, elevate and depress the pads by action of the pleural
leg muscles; and ultimately. in the case of the meso and metathoracic
lobes, as flapping aerofoils, powered mainly by bifunctional leg muscles
including those operating in the Blattodea and perhaps supplemented
by others now retained only in Odonata.
itt tartok 12:42
LEG MUSCLES AND WING SCLERITES AS ORIGINAL MECHANISM: The original
use of the wing sclerites, small hard areas above the legs on the
side integument could theoretically fill the roles of movable surfaces
either for reflection of light or production of sound. ILL
All this about leg muscles also functioning in other functionns means
that, first, existing sets devlope from previously exoisting sets
and secondly, that the coxo- muscles may very well have been active
in the propsed thoracic vibration mechanism, perhaps as a modulator
of a base vibration. Or more detials:
THEORY OF EXACTLY HOW LEG MUSCLE COULD MOVE SIDEPLATES FOR SOUND OR
VISUAL SIGNALING: If the coxal motor muscle is activated while the
insect's leg is not free to move, asit quite commonly may be when
holding on to the substrate, like a plant stem, then, since the leg,
which is the insertion part cannot move, the part which is the origin
of the muscle will tend to move. If this part is a small structure,
such as the wing sclerites, the coxal muscles could quite possible
vibrate it.
13. ROLE OF MATING DISPLAY The idea that the original use of wings
was in mating display, as suggested by some authors, and the
present proposition mutually sopport each other. CAN ADD MORE HERE
The generality of the appearance of wings in the last instar is significant,
and has many corroborating facts: Ephermeroptera, termites, ants,
the holpometablous insects, the mating/species identifier function
of wings in Lepidoptera, etc. This could be all secondary development
but presently we have no way of checking the facts.
15. LEG MUSCLES SAME AS WING MUSCLES --already covered above? (Wooton
p 248 and Davies ILL) YES
16. MORE SUPPORT FOR SOUND/VISUAL ORIGIN OF FLIGHT: WING ACTION AS
DISTORTING FUNCTION: The action of the indirect muscular activation
of the wings can be technically described as the deformation of a
plate or membrane. ILL. The principal in the action of sonic
transducers such as headphones, speakers, or eardrum are identical:
deformation or distortion of a membrane. Again there is a shared function
in the wing mechanism and audio functions. As a matter of fact, under
the right circumstances we could build a model of a flying insect
by designing a strong miniature speaker with wings attached to the
vibrating cone and by electronically controlling the vibrations we
could make it do somthing that might range from lifting up to just
tipping over on one side. To obtain forward flight it would be helpful
to have a composite speaker whose membrane would be divided into several
adjacent membranes each controlled by a different circuit. ILL
The proprioreceptor systems of insects are also based on deformation
sensing. Unlike the vertebrates, where body movement is detected by
deformation of muscle, it is supposed that in insects the same is
mostly perceived by sensing the deformation of the integument.
All this suggests that thoracic deformation for visual or auditory
purposes had a considerable likelihood to be the source of flight.
END OF SUPPORT
(CICADA TYMBAL COVERED! -- supports possibility of interior sound
production. Natbe earliest thoracic sound producer had a membrane
and this later developed into the lobe. UNLIKELY !!)
SYNECHIA ?
A theoretical reconstruction of the development of flight: i n
s t e p s:
The material source of click mechanism is indisputably present: the
sclerotized plates (terga, sterna, ?pleura), sclerites, tissues of
various degrees of elasticity are
Its energy source is the muscle and its design is the snappiness of
a folded piece of elastic laminate
2. As to the problem of the Odonata not having click mechanism
(and ...) Not having a clicking mechanism: may be lost in these
because large wings beating slowly do not need it. or else SUBALTERNATE
NEW THEORY: it all started with slow bending of side cuticle to pulsate
light w/o click mechanism. this is not good! Lacks ontogenic oxypragma.
OKAY saved: PRINGLE 455 - this idea is now placed above, after click
mechanism idea
PHILOSOPHICAL COMMENT
The accepted theory of lobes leading to parachuting, etc. is at first
glance the most direct route leading to flight, therefore it is obvious
why so far we had accepted it. . But the alternate theory proposed
here offers a more direct path, which at first glance seems indirect
in that it presents a totally unexpected origin for a function. However,
1) the existence or survival of the proposed original functions seems
to say: here is the original function still going on, the secondary
function is oxypragmatic, it automatically arises from the first when
conditions are right, and
2) Many biological structures functions were reasoned out to derive
from unexpected sources. Take for example the origin of the vertebrate
jaw and auditory organs derived from gill arches, take the ...
EVALUATION OF THE PROPOSED THEORY:
The proposed theory meets the requirements posed:
1. The ontology of the wing
2. The oxypragma of the earliest wing
3. Its polypragma, if any
4. The ontology of the flight mechanism. the oxypragma of the flying
5. Support by other facts
6. Survival or presence of proposed original functions.
1. Charts of evolution of flight (One or more)
2. TABLE OF COMPARATIVE CORRELATIONS BTW WING AND TYMBAL
Text: The point of this information: since it is reasonabl;e to assume
that sound producation, including the tymbal mechanism, is an older
defvelopmetn the emergence of whichi is relatively simple to imagine,
it is possible to posit thta flight, a far more complicated design
assignemtn is subsequent to the appearnace of resonaniting membrane
system. Therefore it is reasonable to asume that if there exists an
unusually strong analogy and conceivably even homology between the
two systems, the earlier one may be a basis for the devlopment of
the later one. In other words the machanism of flight profers nothing
to positively deny that it was not originally a sound produceing mechanism,
perhaps of the tymbalic sort.
TABLE HERE
3. Stridulation leading to saltation
SALTATIO EX STRIDULATIONE
In the saltatory Orthoptera we see an interesting interrelation between
the development of the femur for competent jumping and the use of
the femur and elytra in stridulation. Here we see two functions that
support each other and also share one structural element.. If the
femur evolved for saltation it also supported emergence of stridulation
and vice versa. Therefore one or the other could have provided the
nursery condition for the other. Based on this concept an argument
is presented in the Appendix proposing that in fact Orthopteran
saltation evolved from femoro- or tibio-elytral stridulation, in
which case flight preceded saltation in this order.
WHERE DOES THIS GO??? TO STRIDUL origin of JUMP, where
it doesn't Support! Most acridoids make no sound! "Actually,
the majority acridoid world fauna is formed by the Catantopinae, Pyrgomorphidae
and Acridinae, which have no sound producing mechanism, or only poorly
defined ones. It is worthy of notice that an expansion of the medial
area of the hindwing, forming a tympanate area, occurs not infrequently
in some Acridinae in which no specialized sound-producing organs are
known, for example in Acrida, Amohicremna, Entryxalis and others;
Acrida, however, makes a distinct flight noise. B. Uvarov,
Grasshopper and Locust, Cambridge U Press, 1966 (I THINK this
is really supportivE!)
SUPPORT for STRIDULATION LEADING TO JUMP: There are femoro-tegminal
and tibio tegminal mechanisms for stridulation. Of tibial types, subfamily
Hemiacridinae has rubbing by "inner spines or spurs of the hind tibia."
( though direct observations on action are lacking. Uvarov Grasshoppers
and Locust p ?
But then this IS SUPPORT: "Several genera of African and Asian savannah
grasshoppers have spines on hind TIBIA, and they rub these against
the usual scrape vein of the tegmen, but they also have the usual
femoro-tegminal mechanism. "They also have well developed tympanate
areas of the tegmina" Uvarov p.180 . AND there is another common
mechanism: tegmino-femoral! Here roles are changed, femur has a simple
scraper ridge, "which rubs against a specialized intercalary vein..."
<<Uvarov, but THIS is not important!
12. LEG MUSCLES partially SAME AS STRIDULATORY MUSCLES IN ACRIDOIDS.
"In acridids, where stridulation is produced by movements of the femora,
muscles at the pleurocoxal and coxotrochanteral joints are involved.
Some of these muscles have a dual function, since they also move the
wings during flight. In all the grasshoppers species studied the order
of activation of the muscles is the same, with fast units becoming
active after slow units." (Chapman, p. 686) GT: This may be a record
of evolutionary development: the slower neural activity belongs to
visual and audio action, while the fast ones, secondary to the slow
ones, developed for added intensity and velocity needed for flight.
also: "Most (but not all) of acridoids have a pair of tympanal organs
on each side of the first abdominal tergite" Uvarov, p.189 (THIS GOES
TO CICADA TYMPANUM SUPPORT?)
(APPENDIX, continued))
POSSIBLE ORIGINS OF SOUND COMMUNICATION
With walking established in the evolution of insects, many sclerites
on the body and on the legs actively articulated, rotaed, rubbed against
each other. All this action would take place by the integument with
its soubnd producing potential. Thereofer it is possible that at the
insect level thses actions may produce adventitious sounds. There
may be tiny creaking, squeekiing, scraping and rubbing noises present
and since insects appraoch each other in proximity and experience
tactile interactions, these noises or low level vibrations may be
perceived by them through audio or tactile receptors.
Later, with pterygotes we also can speak of wing rustling when folded
and tucked, but the noise production of sclerites, if it exists to
a significant degree, goes back to rather early times of inesct history.
The question poses itself: if noise production and perception exists
at such level, and if it no doubt is ancient, could this be the primitive
psycho-physical basis of species recognition by sound in insects?
Once there was a code of recognition built on olfactory, visual, and
audio perception, sound could be an effective medium for communicating
at increasiung distances.
POSSIBLE ORIGINS OF THORACIC SONIFYING
Here we have to find some structure that could adventutiously produce
thoracic sounds. Perhaps breathing, a function today serviced by the
abdomen, was once also perfored by the thorax. Such temporary structural
changes as occur in breathing could offer a basis for sound production
by that body part. Breathing is affected by some combintaion of compression
and release, achieved by intersegmental musculature and so action
could become the source of a sonification process leading to vibration
of the thorax by deformation.
But since the thorax early in insectan developmetn was assigned to
house the legs and their base musculature, the movement of the coxa
could also originated a defvlopment towards thoracic sonifying or
perhaps, visual signalling. Just to suggest a possible event that
could relate leg movement to sound production, let us look at the
leg base musckuature of the typical insect.
ILL The promotor and remotor muscles of the coxa (which move
rotate the coxa forward and backward) connect the coxa with the pleuron.
The muscles originate on the pleuron which is the stable part and
they are inserted on the coxa, which is the moving part. But consider
the casewhen the insect is holding on to the substrate, let us say,
a plant stem. If the tarsus, or "foot" of the insect, grasps the stem,
and generally flexes the leg muscles so that the leg is anchored against
moving it, then if these coxopleural muscles are stimulated a reversal
of mvement might take place: the coxa will remain statioanry and the
pleuron will tend to move concavely inward. Repeated flexing of these
muscles will tend produce and inward-outwrd movement of the pleuron.
WING FOLDING - AN ALTERNATE ORIGIN - VISUAL AND NUPTIAL FUNCTIONS
If we picture primitive wings either before or after flight had been
achieved, employuing their wings as visual signallers, describing
rituals
Having developed into large surfaces through their their visual
display function, pre-flight wings would probably produce pulses of
whirl or buzz at various rates as well as slower visual movements,
mainly rotation around the body's long axis. But what if competition
selected for a wider range of movements and therefore developed a
fore and aft flexing of wings? This is not unreasonble to expect and
would permit us to make the conclusion that flexure of wings and its
consequent folding may have evolved before flight. Such poitn of view
would seem to settle the question whether Orthopteran and Ephemeropteran
inablity to flex wings is primary or secondary.
The fatc that relatively large wings in a pre-flight insect might
be pyisical obstructions means that folding could also have evolved
for that reason, as the accepted theory states. But there is an argumnt
that would eliminate this posssibility. And this argument is in fact
one broiught up in the acpeted thoery, namely that eraly wings may
have had to do with nuptial flight. If so then the nuptial period
belonging to the last instar, with a purely reproductive role and
without a need for nourishment, would permit large wings whether folded
or not since survival and escpae would be not be a high enough criterion
at this stage. However, the issue is doubly clouded by the finding
of an adult Ephemeroptera with functional mouth parts in the fossil
record (SOURCE...) and by the fact that living Ephemeroptera do not
fold their wings.
This idea of wing folding predating flight has been stated by at
least one author although still in the context of the accepted theory:
S. M. Manton writes "A narrowing of the wing base and added complexity
in structure could lead to the ability to fold the wings when not
gliding....Simple flapping flight presumably came after the ability
to fold the wings." (The Arthropoda, p. 428).
SUPPORT: for WING FOLDING PRIOR TO FLIGHT
R. J. Wooton says (p. 250 "(Equally) uncertain is the position
of the first wings, both in in flight and at rest. Apparent homologues
of the flexor muscle have been reported in both Ephermeroptera and
Odonata; ...but it is hard to believe that the Neopterous condition
was present from the first. (GT: HE IS WRONG)Yet the resting position
of the wings found in Palaeodictyopteroids and Anisopterous Odonata
renders these latter insects so wholly dependent on aerial locomotion
that it seems very probable in early, weakly-flying insects. A more
feasible alternative is that adopted by Ephemeroptera, whose wings
are held above the body at rest, but partly remoted. \
SUPPORT: GLIDING OR FLIGHT MAYN"T HAVE BEEN THE ORIGINAL FUCNTION
QUESTIONS ABOUT THE ORIGINS OF JUMPING --
DID SALTATION arise from stridulation IN ORTHOPTER? and NURSERY
How did jumping, using legs, originate? Jumping works through a relatively
gradual build- up of elastic muscular tension which is suddenly released.
The muscles involved should be of maximum cross section to yield maximal
force and alsp short so that their release would take minimal time
in returning to relaxed state. All this would need a context and time
for developing. How would such requirements be filled? It seems that
such development of unusual muscle triggering is possible based on
a anomalous triggering of muscles by the neural system, which alone
is responsible for such timing and perhaps the build-up of femoral
muscle mass would be a secondary development. Such evolution obviously
must have taken place with the various types of jumping insects, however,
with Orthoptera another origin for jumping can be postulated. This
is covered below, in SALTATIO ex STRIDULATIONE.
M. D. Atkins, Introduction to Insect Bechavior, Macmillan, 1980
D. J. Borror, D. M. DeLong and C. A. Triplehorn, An introduction
to the study of insects, 4th edition, Holt, Rinehart and Winston,
H. B. Boudreaux, Arthropod Phylogeny with Special Reernce to Insects,
R. F. Chapman, The Insects, 3rd ed., Harvard U. Press, 1982
R. G. Davies, Outlines of Entomology, 7th ed., Chapman and Hall, 1988
G. M. Hughes and P. J. Mill, Locomotion: Terrestrial, in M. Rockstein,
ed., The Physiology of
P. T. Haskell, Insect Sound, Witherby, 1961
U. Lanham, The Insects, Columbia U. Pres, 1964
S. A. Manton, The Athropoda, Clarendon Press, 1977
W. Nachtigall, Insects in Flight, McGraw-Hill, 1968
D. Otte, North American Grasshoppers, Harvard U. Press, 1984
J. W. S. Pringle, Locomotion: Flight, in M. Rockstein, ed., The
Physiology of Insecta, vol. 2.
O. W. Richards and R. G. Davies, Imm's General Textbook of Entomology,
10th ed., Chapman
A. G. Sharov, Basic Arthropodan Stock with Special Reference to Insects,
R. E. Snodgrass, Principles of Insect Morphology, McGraw-Hill, 1935
B. Uvarov, Grasshoppers and Locusts, Cambridge U. Press, 1966
V. B. Wigglesworth, Life of Insects, World, 1964
V. B. Wigglesworth, The evolution of insect flight, in Insect
Flight, edited by R. C. Rainey, Symposium of the Royal Entomologival
Society of London, 1976
R. J. Wooton: The fossile record and insect flight, in Insect
Flight, edited by R. C. Rainey, Symposium of the Royal Entomological
Society of London, 1976