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<<A living being has a certain way
of life, a mutation appears, this way of life provides selectionary pressure too keep this mutation, and afterwards the mutation is called an adaptation. And adaptations like wing feathers (or limbs, for that matter, in the origin of tetrapods) can be exapted for use in other ways of life.>> The mutation happens----> the caracter(s)
that that are the espression of the genetic mutation are under a selective
pressure(with the whole animal bearing it) and if this mutations gives some
advantages to the animal, against other animal of the same species,( and in
general against all the "forces" that will deny it survivaland thus reproduction
) with the "old" caracter(given the possibility of the permanence of the
same enviromental conditions for some generations), then it will probably
become the most present "version" in the population;
you wrote., <<this way of life provides
selectionary pressure
too keep this mutation>>I don't understand what you mean by "selctionary pressure to keep this mutation" the selective pressure is on, the mutation,
meaning( i know i write not very well, i'm sorry; hope you understand what
i mean) that it's not acting to keep it( it sounds like "trying to preserve the
mutation"), but against it.
<<Dippers hunt aquatic insect
larvae.>>
ok
<<Remember the tail of *Archaeopteryx* that
prevented it from gliding? >>
Mr Cunningham answer to this...
<<Prey in
the mouth would have pulled the center of gravity forward and thus made flight easier. >> has someone tried to quantify this
"easier"?
<<Well, then, why has flight only evolved
three times among vertebrates and
not three hundred times? Or, on the other hand, much earlier?>> maybe because the phisical features (not the same
in the three cases, surely) needed to be able to get in the air evolved
rarely; and , however, i don't think it's sufficent to have these
features: contingence has its role, an important one.
<< in the air above
small ones, there are the same insects as on the dry land around.>> Infact I said that , given the possible use of this
scenario( an aquatic theropod trying to get something in the air from the water
surface) as one of the reasons that possibly led to the evolution of flight, it
would be nothing different from the scenario imagined as a support to the
ground-up theory.
Have you ever talked about large masses of
whater?
<<if you can detect one in the
hypothesis
I presented... and if I can't "discuss it away"...>> I think the dynamic ones and the others regarding
the possible reasons for the evolution of flight from swimming theropods are
quite correct and you haven't demonstrated that I'm wrong in my observations
(because no studies have been done, surely....).
<<The wild form of the domestic chicken that
lives somewhere in South East
Asian jungles doesn't fly more.>> what are their predators?
<<I'm quite sure predator pressure hasn't
changed much since the Permian or
so. Why should it have?>> maybe i told badly what i wanted to say, because
this answer doesn't make much sense to me.
the predator pressure is sctrictly related to the
particular habitat you look at; it depends on what kind of predators are
present, how many different kinds and so on; predatory animals have changed a
lot from permian times so i don't really understand what you mean.
Big flightless birds evolved in australiaand other
isolated(big or small) enviroments because of the absence of big predators..you
know how the story ended.
<<You know, ostriches and rheas have evolved
flightlessness in environments
that were always full of predators>> I'd like to know something more about this, if
possible.
since I've always thought big flightless birds
evolved in relatively "hunterpoor" enviroments...
however do you want to compare the running
abilities of chickens and ostriches?
"In a jungle, hiding from predators is very
easy."
oversimplifying...
predators can hide as well....
<<But this doesn't explain in any way *how*
"the features
needed to get in[to] the air" *evolved*, >> infact..
<<I'm the one who has probably written the
longest post in the history
of this list. :-]>> we will probably end up writing very much
indeed;-)
..it would be even more if someone else wanted to
join the discussion....=)
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