Metamorphoses and insect flight; How bugs got their wings.

[enoch]

Why is it that a caterpillar has little resemblance to a butterfly ?

Darwinian evolutionary models have yet to explain how this abrupt transitional phases could develop in a liner way.
The following is probable non linear explanation of how the pupa stage of insect development could be compressed into and adaptive evolutionary stage toward flight.

One mechanism needed, is for the flightless
ancestors of the insects to develop a morphological feature that could accumulate information toward flight.

But that still can not explain the whole metamorphoses process.

How would this developmental leap of the pupa stage be compressed in this way?

I believe the key steps to build this new body plan lies in the molting stage.
In the pupa stage the wings appear to form from the outer skin. This then must be the morphological feature that collected the Information needed over generations to develop flight. Just as the bird developed the capability of flight though the tail feathers.
But how?


Here is a scenario; eggs hatch in the ground, the caterpillar climbs into the trees and feeds an grows. It goes though a molting stage during this stage it climbs to the high part of the tree and uses the still connected, but light weight skin to catch the wind and disperse though the air.

This cyclical adaptation will not only form wings but will simultaneously become compressed and combined into the molting stage.



But, prior to that [millions of years ago] the skin would be retained just long enough to catch the wind and disperse the caterpillar though the environment. As soon as the caterpillar landed it would finish molting and discard the "sail" of light skin and remain a caterpillar.
After millions of generations of this process it will transform the temporary sail into a permanent set of wings.


This cyclical adaptation will not only form wings but will simultaneously become compressed and combined into the molting stage .


The pupa is nothing more than a complex adaptive molt, That has developed over time by compressing information of past complex molting behavior.

Its quite simple.


The partially molted skin is the morphological feature needed to collect information to create wings. They become the wings.

[PlayTOE]

The idea that bird flight developed from tail feathers is yet unproven and only a proposal.
Your molting hypothesis is reasonable but also lacks proof.

[cheaky monkey]

It is believed that metamorphisis evolved to split the generations. By haveing two seperate forms (one that is a herbivore and one that is a pollinator) the populations can reach massive sizes without reaching the carring capastity.


They (Entomologys and palaeoentomologests) believe that wings developed from a second set of limbs that were present on all body segments (not the 11 or so head segments). Many arthropods have two limbs on each limb (doesnt sound right, maybe sounds better two say two limbs from each limb bud? I don't know how to say it, look at a crabs leg).

I dont know the embrology behind this. But they have found early fossil pterygota's with wings on every body segment. In addiion to this, they suggest that the wings had to evolve from articulated and circulated (with trachia and what not) for them to be any use.

You are correct though about the molting. The final stage is the most important for holometabola.

you said
'In the pupa stage the wings appear to form from the outer skin. This then must be the morphological feature that collected the Information needed over generations to develop flight'

This is incorrect. I am not sure if you are getting pupa and larvae confused, but anyways, holometabola develop their wings internally (thats why they are sometimes refered to as endopterygota). You should try catching a caterpillar from the garden or something and watching it develop :) its fun!


Your scenario is wrong on several accounts

1) It does not explain wing development in the majority of the holometabola. Ie. grubs (coleoptera) and maggots (diptera) that do not climb trees but are either sub terranian (expect for the case of a few predatory larvae which dont realy need to be mentioned here) or live in dead/dying bodies.

2) Wings develop internally and do not even begin to develop untill the pupae stage.

(might be a good scinario for hemimetabola (that are exopterygot's) but their wings do not do anything that is has been observed untill they are fully developed)


It is currently believed that holometabola develop the cyclical body shape because it is more primitve (ie like some insect far back in time).

3) All the evidance found so far says your theory is wrong :(.


This, 'The pupa is nothing more than a complex adaptive molt' is correct though.

another question sorry.

What about apterygota that continually mault throughout their lives and never develop wings?

again, this is not an attack at you. I just spent 6 months studying entomology so all this stuff is fresh in my head.
cya

[PlayTOE]

It is always best to look at the data before jumping to a conclusion.

[enoch]

The pupa stage is where the butterfly makes its incredible change from the larva to the adult. Most butterflies remain in the pupa stage between one and two weeks. During this time inside its pupa, the larva is transforming its body parts into those that the adult will need for it new life as a butterfly. In place of mandibles, the proboscis will begin to form to serve the adult and its liquid diet. Wings will be formed from the thorax, and the parts of the head will undergo drastic changes in appearance. Visible changes on the outer layer of the pupa can be noticed as the adult butterfly begins to develop within

[cheaky monkey]

and...?

[enoch]

Your scenario is wrong on several accounts

1) It does not explain wing development in the majority of the holometabola. Ie. grubs (coleoptera) and maggots (diptera) that do not climb trees but are either sub terranian (expect for the case of a few predatory larvae which dont realy need to be mentioned here) or live in dead/dying bodies.

2) Wings develop internally and do not even begin to develop untill the pupae stage.

(might be a good scinario for hemimetabola (that are exopterygot's) but their wings do not do anything that is has been observed untill they are fully developed)


It is currently believed that holometabola develop the cyclical body shape because it is more primitve (ie like some insect far back in time).

3) All the evidance found so far says your theory is wrong .



another question sorry.

What about apterygota that continually mault throughout their lives and never develop wings?

This has nothing to do with what im am saying.

[cheaky monkey]

you do not understand. IT HAS EVERYTHING TO DO WITH WHAT YOUR SAYING

If you want to propose a theory, gather real evidance first besides what just sounds good.

Do you know how molting works?

Most of the exoskelleton is recyled when it is molted and it is only the small outer cutical that is acculy lost. If you dont understand this, go read a book and get informed.


Do you know about the strucutre of the exoskelleton?

Your hypothesis tells nothing us nothing about how these 'loose folds of skin' acculy support the animal.

AND if this was the case, which it is not, wouldent there be a continuous development towards smaller body mass? I think a lot of caterpillers are large.


What about beatles that dont even move much, just stay underground. How does your hypothesis explain this? Or diptera (mosquetoes) that swim and never see the surface of the water?

And the endopterygote life cycle was around before the various orders within the holometabola split.

I am trying to have a discussion with you, not a fight.


One more thing, the pupal stage of many holomotablous insects (not including diptera) last longer then one year (heard of a few species that last a few years).


[edited to remove abuse]

[enoch]

It is believed that metamorphisis evolved to split the generations. By haveing two seperate forms (one that is a herbivore and one that is a pollinator) the populations can reach massive sizes without reaching the carring capastity.

There is no logic in this statement, you just can't say things are the way they are because they intended to be that way.
Science is about solving problems.
I’m describing a process of development.

[cheaky monkey]

Your not solving problems. You create problems and attempt to solve them with no evidance

It is believed that metamophisis evolved to split the generations. This is what all the entomology text books discuss. It would have immediate advantages.

Even hemimetabous insects have some advantages. (juvinals can not disperse, where as adults can). Palaeoptera (dragonflies and such) do a similar thing. They have aquatic larvae and flying adults. This is spliting the generation and allows populatoins to reach a greater size. This is not backword thinking.

[cheaky monkey]

I’m describing a process of development while you are merely stating the obvious and the irrelevant.

You dont know anything about the development of wings, and your changing your story. In your first post you said that wings came from parts of the cutical that had not fallen off or something similar. This is not true, and has never been observed. And many, if not most holometabolous insects do not live in the trees (and im sure thoes that do, would not live at the tops of them).


How is correcting your mistakes irrelevant?

[enoch]

Your not solving problems. You creating problems from nothing and attemping to solve them with ridiculous logic and no evidance

It is believed that metamophisis evolved to split the generations. This is what all the entomology text books discuss. It would have immediate advantages.

Hell, even hemimetabous insects have some advantages. (juvinals can not disperse, where as adults can). Palaeoptera (dragonflies and such) do a similar thing. They have aquatic larvae and flying adults. This is spliting the generation and allows populatoins to reach a greater size. This is not backword thinking.


Again, because you dont understand (or cant comprehend what I'm saying, dont insult me (by telling me i think like a creationest)

But you are presenting an intelligent design scenario when you ignore the incremental steps that lead to present overall morphology, these phylogenic steps reflect evolutionary adaptive steps occurring over long periods of time in the distant past.
You keep parroting what you’ve read without the consideration of what you don't know.

This is creationist thinking……… there are gaps in our understanding of the development of insect flight and the pupa stage.
This is a fact!!!………… there is a need for more information and perspective on this subject, what you keep presenting does not address these gaps.

Again……………. this is confusing the map with the territory.

You keep expressing what you know, this is not of real importance.
We all have the internet, everyone’s can be an expert……….. try thinking and then providing new perspectives on a subject then we can have a conversation that’s worth having.

[enoch]

I’m describing a process of development while you are merely stating the obvious and the irrelevant.

You dont know anything about the development of wings, and your changing your story. In your first post you said that wings came from parts of the cutical that had not fallen off or something similar. This is not true, and has never been observed. And many, if not most holometabolous insects do not live in the trees (and im sure thoes that do, would not live at the tops of them).


How is correcting your mistakes irrelevant?

I’ve never observed a fish turn into an amphibian, or a human descend from the trees, but then again I can think about scenarios that follow rational lines of information and reason.

So from what you’ve stated you believe if an evolutionary stage is not observable then it is not science. This again is the intelligent design party line……. If it cannot be observed it cannot be inferred by evidence…….. so you are a creationist at least in your basic world view.

[wolfhnd]

Would you guys quit insulting each other, just agree to disagree :-)

[PlayTOE]

Enoch I have been looking at your idea and discussion. Nothing Cheaky mentioned is remotely creationist. He has been attempting to put your idea into sound footing so you can pursue it if there is any possible pattern to develop.

Jumping to a conclusion and staunchly defending it is not science. Coming up with an idea and checking the evidence to see what if any known facts either support it or counter it is the way science reasons.
You have an idea. Cheaky has some entomology knowledge. This is a room to learn.

[enoch]

Nothing Cheaky mentioned is remotely creationist.

It is believed that metamophisis evolved to split the generations. This is what all the entomology text books discuss. It would have immediate advantages.

This statement suggest a prior plan for advantage without considering the steps for sequential advantage this suggest intelligent design did you miss this are or you ignoring it.

[PlayTOE]

Texts and discussions commonly use terminology that could suggest there was “prior planning” in evolution. We know this is not the intent, and do not fall into the trap caused by language deficiencies. It of course is better to be more specific and say

It is believed that metamorphosis evolved due to the generations split. This is what all the entomology textbooks discuss.

The development of a metamorphic stage is interesting and clearly took time to arise. There were probably several steps to it each with some development rather than one large step with small slow development. Still, expectations and guesses are not the same as proof. We need to look at evidence and then draw conclusions.

[enoch]

You have an idea. Cheaky has some entomology knowledge. This is a room to learn.

This is exactly the point, but first understand and comment correctly on the model being presented.

Would you like me to go back and collect the incorrect misleading misinterpreted statements cheeky has made over and over again about my models.

[PlayTOE]

Actually, just edit to remove the personal commentary in each of your messages, (both parties).

[cheaky monkey]

I’ve never observed a fish turn into an amphibian.

It has been know for many years (before darwin) that the stages (or events) of evolution can be seen in the developing embryo. For example, when human embryos are developing they go theough a stage where we have gill slits and tails and what not. (yes we dont look like fish, i am not suggesting this im just saying we can see derived characters in embryos as they develop) Also, more cloesly related animals look similar for longer amounts of time as they develop.

Here is a scenario; eggs hatch in the ground, the caterpillar climbs into the trees and feeds an grows. It goes though a molting stage during this stage it climbs to the high part of the tree and uses the still connected, but light weight skin to catch the wind and disperse though the air.

1)Caterpillars that tend to live in trees tend to have their egges depostited on the trees in which they inhabit.

2) The exoskelleton of larval stage insects is different (does not have as much tanned protein (sorry dont know the correct term) in it, so it is more flexable) then the hardend adult exoskelleton.

3) This scenario only takes into account a small percentage of the holometabola clade. If you want a decent sounding theory, i suggest you learn more about the majority of larval stages that are immoble (or move very little eg. hymenoptera (ants bees wasps) or many coleoptera (beatles) larave )


If you are suggesting a theory of wing development, you are looking in the wrong clade.

Anyways, holometaboly did not happen instantly (as playtoe said) but too a long time. I don't feel the need to highlight this each time i suggest something evolves or something similar, i take it as common knowledge. I am sorry if you have missunderstood me. It is believed (as by P.J. gullan and P.S cranstion (The insects, third edition) that the holometaboly life style evolved from a pronymphal stage (my gf is here, but when she goes in an hr ill copy out the section (about 9 paragraphs, its very interesting).

[enoch]

enoch wrote:
Here is a scenario; eggs hatch in the ground, the caterpillar climbs into the trees and feeds an grows. It goes though a molting stage during this stage it climbs to the high part of the tree and uses the still connected, but light weight skin to catch the wind and disperse though the air.

This cyclical adaptation will not only form wings but will simultaneously become compressed and combined into the molting stage.



But, prior to that [millions of years ago] the skin would be retained just long enough to catch the wind and disperse the caterpillar though the environment. As soon as the caterpillar landed it would finish molting and discard the "sail" of light skin and remain a caterpillar.
After millions of generations of this process it will transform the temporary sail into a permanent set of wings.

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1)Caterpillars that tend to live in trees tend to have their egges depostited on the trees in which they inhabit.

Again no logic applied, and your taking what I’m saying out of context. Would you say..................
Birds tend to build their nest in trees therefore their flightless ancestors lad their eggs in trees ?

You really don't seem to be able to grasp the difference between evolutionary adaptive steps with modern behaviors and how they relate.

[cheaky monkey]

Enoch, i have nothing against you. I think your ideas are great for discssion. When you insult me it speaks poorly of your character.

Yes we disagree, not much in the bird feather thread, where i say flight feathers evolved on the limbs and the tail and where you say just on the tail. I liked this, it showed a few different ways feathers could have evolved and their uses besides flight, mating and insulation. To here, where you say wings evolved from loose bits of exoskelleton (or loose weight skin (which insects do not possess, but i assume you mean exoskelleton) to form wings. Just because we dissagree does not mean we can't be friends.

The only reason why i dont like this hypothsis is that there is no evidance. Infact, everything bit of evidance that has ever been gathered disagrees with what you say.

This is how i understand what you say:

Holometabolous insects (for which caterpillars are) developed wings from loose bits of exoskelleton that did not fully fall off from a prior molt.

enoch wrote: 'It goes though a molting stage during this stage it climbs to the high part of the tree and uses the still connected, but light weight skin to catch the wind and disperse though the air. '

If you show me evidance for this, i will be happy to be more included to believe your hypothesis.

[enoch]

All these insects developed flight in basically the same scenario it doesn’t matter if the larval stage was in the water the ground or a tree, the point is this after eggs are hatched the larva feed and grow. The next necessary step is for the adult mating stage to disperse though the environment, whatever the clad.
Spiders developed silk to catch the wind some achieved this by utilizing the molted exoskeleton in the same fashion some used both. How do you think the silk worm developed the silk cocoon

This is yet another adaptive link of the need to utilize the air to disperse. Over millions of years these insects developed better and better dispersing techniques. The spiders web didn’t evolve originally to catch prey any more than; “metamorphosis evolved to split the generations” flying insects evolved so the breeding adult could radiate outward and mate with non hatch mates.

[cheaky monkey]

I am copying out a section from my text for everyone to read (it doesnt argue for or against any of your theories i just think its interesting) Please take the time to read it for i have taken the time (about 20 min so far) typing it out.

[cheaky monkey]

Wing development from The insects: outline to entomology, 3rd edn

'one of the longest-standing hypotheses attributes the origin of the wings to postulated lobes, derivations from the thoracic terga, called paranota. These lobes were not articulated and thus tracheation, innervation, venation and musculature would have been of secondary derivation. The paranotal love hypothesis has been displaced in favor of one infeering wing origination from serially repeated, pre-existing, mobile structures of the pleurong. These were most probably the outer appendage (exite) and the inner appendage (endite) of a basal leg segment, the epicoxa. Each protowing or winglet was formed by the fusion of an exite and endite lobe of the respective ancestral leg, with exites and endites haveing tracheation and articulation. Fossil evidance indicates the presence of articulated winglets on all body segments, best developed on the thorax. Molecular studies of development seem to substantiate the exite-endite model for wing origins.

The exite-endite hypothesis of wing origin can be reconciled with anotehr recurring view: that wings derive from tracheal gills of an ancestral aquatic 'proterygote'. Although the earliest insects undoubtedly were terrestrial, the earliest pterygote insets probably had aquatic immature stages. Thes abdominal gills of aquatic mayfly nymphs may be homologous with the abdominal winglets of the protopterygote, and serially homologous with thoracic wings. Winglets are postulated in aquatic juveniles to have functioned in gass exchange and/or ventilation or even to assist in swimming, with the terrestrial adult co-opting them for an aerodynamic function.

All hypotheses concerning early wings make a common assumtion that winglets originally had a non-flight function, as small winglets could have little or no use in flapping flight. Suggestions fro preadaptive functions have inculuded ann or all of the following;

-protection of the legs
-covers fro the spiracles
-thermoregulation... [edit. list goes on]

Aerodynamic function came only after enlargement. However, aquatic nymphal gills may even hvae been large enough to give some immediate significant aerial advantage if retained in a terrestrial adult.

The manner to which flight evolved is also highly speculative and contentious but, what ever the origin of winglets, they come to assume some aerodynamic function. Four routs to flight have been argued, via:

1) Floating, in which small insects were assisted in passive dispersal by convection
2)Paragliding, in which winglets assisted in stable gliding or parachuting from trees and tall vegetation
3) Running-jumping flying
4) surface sailing, in which the raised winglets allowed the adults of aquatic insects to skim accorss the water surface

The first two of these hypotheses apply to equally fixed, non-articulated winglets and to articulated by rigidly extended winglets. Articulated winglets and flapping flight can be most easily incorportated into the running-jumping scenario of developing flight. The floading

Im not going to finish this section.

[cheaky monkey]

'The spiders web didn’t evolve originally to catch prey any more than; “metamorphosis evolved to split the generations” flying insects evolved so the breeding adult could radiate outward and mate with non hatch mates.'

yes i dident say it right. I am trying to have a friendly discussion.

good luck convincing any entomologest that the 'loose skin that dident completly molt' was what first produced the wings.

OH and this was in a catepiller too. Next time you suggest an evolutionary theory, look to the more primitive members of that group.


how would loose skin support a body?

[cheaky monkey]

Spiders developed silk to catch the wind some achieved this by utilizing the molted exoskeleton in the same fashion some used both

HAHA yeah, i believe that (not joking). But they can not gain control of the exoskelleton and are at the murcy of the wind. A lot of wingless aphids do the same thing. And it is only small spiders that utilize this because the exoskelleton can not support their large size.

THE DIFFERENCE BETWEEN THIS AND INSECT FLIGHT IS CONTROL.

controlled flight.

Read a book, you keep comming up with all these hypothesis with abosulutly no evidance.

And no, reading stuff on the internet does not give you the same quality of information as going to university.

[enoch]

I’ve worked very hard developing non-linear evolutionary models over the past ten years all I every tried to do here is have someone attempt to read them and understand the view point and comment on it.

[cheaky monkey]

why cant we just call a truce,
here again:

Enoch, i have nothing against you. I think your ideas are great for discssion.

Yes we disagree, not much in the bird feather thread, where i say flight feathers evolved on the limbs and the tail and where you say just on the tail. I liked this, it showed a few different ways feathers could have evolved and their uses besides flight, mating and insulation. To here, where you say wings evolved from loose bits of exoskelleton (or loose weight skin (which insects do not possess, but i assume you mean exoskelleton) to form wings. Just because we dissagree does not mean we can't be friends.

[enoch]

cheeky: good luck convincing any entomologest that the 'loose skin that dident completly molt' was what first produced the wings.

AdR:Consultant, Scientist
In that case, molting would be a prerequisite for the development of wings?

Metatron definitely nails one aspect of this issue: molting is a prerequisite for nearly all major organizational changes in insects. These are animals that periodically grow entirely new skin under the old one. Opens up all sorts of possibilities, while closing others

.Entomology Grad Student Interests: Insect systematics






Its not a question of convincing first, its a question of understand a view point. Convincing is inconsequential until this is accomplished.

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