Papilio machaon - osmetrium

[John Grehan]

>John:  The reversed arguement still says the same thing.

I thought I was saying it in terms of their being a structure and
this is correlated with certain consequences, but I was trying to
rephrase existing statements, so the confusion will be my fault.


>I'm firmly undecided about the chicken or egg, but if, for the sake of
>arguement, large size did automatically produce wide dispersal, which it
>would appear to, it still dosent explain what SELECTS for large, there
>are smaller ones naturally slower and more dim witted, and tastier, AND
>there's millions of them so why a big size?

Does the large size have to be selected for to exist? The widespread assumption
of most biologists is that most, if not all, functional features have to
be selected otherwise they would not exist. I'm one of the few who consider
the possibility that features evolve without requiring an external force,
and the
evolution of new structures may have consequences
in terms of function. I recognize that average size can alter considerably
in many organisms through natural selection, but this does not mean that
selection
is necessarily the only way of looking at the evolution of size.

>The fact is that large size dosen't automatically produce wide dispersal
>(ie: some speyerias and morphos) but in the case where the local food
>supply is missing, strong wings will get you out of there, and
>caterpillars that chase away their littermates have that much less
>restriction on how much they eat, so they COULD BE selected for bigness.
>My unproven contention is that they are.

All the data says here is that in this case the species is able to survive by
virtue of having that dispersal ability, not that the dispersal ability or
bigness was selected for. It might be that certain species or lineages
evolved large size and good dispersal ability, and in such cases this
results in adults locating food supply over a greater area.

And in case you did not see earlier discussion, my view on the
evolution of structures recognizes two mechansims for effecting
improbable shifts in variation - either  natural selection, or
orthogenetic modes (such as molecular drive).

John