Hi doc,
The first winged version appears to be in existence today (top right).
All of the species and the right side of the diagram are in existence today, but what the diagram does not show you is whether there was what would be called "orbitrary speciation" along any of those legs. What you see are the speciation divisions of populations and the final results
50k 50 million years later. Thus the top line could be just as recently evolved as the others, just that all the mommy and daddy species were wingless.
These options carried on right to today and at different stages the options were turned on (I don't think wings or wingless re-evolved).
Ah, but "wing" or "wingless" is not necessarily a single gene, nor is just a matter of turning it on or off. What we are likely seeing is the loss and re-evolution of parts of the whole wing formation process. This process may in fact be broken in different places for different species.
You can turn a feature off by blocking or removing any part of the development critical to the formation of wings, and this would likely leave you with the same original feature that the wings evolved from, plus some genes inherited while winged that are not removed. Thus if a new by-pass is evolved to get around the blocked or removed part it would allow necessarily similar wings to evolve - it would be preadapted to form similar wings.
This would be similar to the "Irreducible Complexity" refuting experiment done with E.coli (see Ken Miller
"A True Acid Test") where an element crucial to the metabolism of lactose was removed from a subsystem, and a new set of elements evolved to replace the broken subsystem allowing the whole metabolism system to function again.
I think if the wings or wingless options had to re-evolve then they would have been significantly different to anything that had been in existence before (is evolution repeatable....I don't think so).
How much is "significantly different"?
Would it not still be working from the same basic features that were there when the wings first evolved? If I remove a sprinkler from the end of my hose I am still capable of watering the lawn, and I can put another sprinkler on the same hose.
If a bat lost the bat wing, would it not still have a hand\paw with finger bones that can evolve back to support a skin membrane?
Is the membrane pattern of the colugo significantly different from a bat?
Does not convergent evolution answer this question best then?
If a possum and a squirrel can evolve into such similar critters from widely divergent backgrounds and many eons from a common ancestor, then is it not possible that the same ecological niche can drive evolution to repeat a similar solution?
how much is "mutation" and how much of what we see is switching on or off of options?
The switching on and off -- if that is indeed what was happening -- is still caused by mutations, so all of it is mutations.
Enjoy.
Edited by RAZD, : correction
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