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Re: BAAD BCF



>In a message dated 95-11-30 17:42:13 EST, ornstn@inforamp.net (Ronald
>Orenstein) writes:
>
>>There is, of course, no evidence that flight evolved to escape predators.
>
>Ah, but there is. The evidence is that, where predators are scarce, birds
>frequently evolve "back" into flightless forms.
>
Sorry, this won't do entirely.  That scenario fits island forms but
flightlessness has also evolved in areas where mammalian predators  are
clearly present (eg the flightless "native hen" of Tasmania, flightless
rails on New Guinea and Sulawesi - to say nothing of most ratites).  In fact
some suggest that flightlessness evolves in island forms because there is a
selective advantage in remaining sedentary and/or growing large on a small
island subject to "ecological release".  And of course many island birds are
not flightless.

Besides we have no evidence that secondarily flightless birds resemble
either morphologically or ecologically the non-flying ancestors of the first
flying birds; as I pointed out earlier secondary flightlessness appears to
involve the retention of infantile characteristics.
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
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