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Re: Exaptation



>       There are probably a couple of reasons bats don't go flightless 
>very often. I don't know if they are quite as good as birds at flying, so 
>they probably have a harder time getting to islands where there are no 
>predators (does anybody, for instance, know if places like the Galapagos 
>and Hawaii or other oceanic islands have bats?) and they just aren't as 
>adept at moving on the ground as birds are.
>
There is one native bat in Hawaii, the endemic Lasiurus cinereus semotus, a
race of the North American hoary bat.  Two species, the hoary bat and the
red bat, are known from the Galapagos; both species, interestingly, are also
known from Bermuda.  The red bats of the Galapagos are an endemic race.

I suspect that the main reason there are not more flightless bats is
twofold: one is that bats are much more aerially adapted than many of the
bird lineages that develop flightlessness (there are no flightless swifts,
swallows or nightjars either, and only one flightless songbird although
songbirds make up more than half of all bird species).  Secondly, the bat
flying mechanism involves both the front and hind limbs, involving many
compromises to the hind-limb architecture, so the development of a
terrestrial volant bat - I would think a necessary precursor to
flightlessness - (equivalent to a rail, say) is far more difficult (though
the NZ short-tailed bat comes pretty close.  This may explain why we have
not found flightless pterosaurs, too (assuming, and ducking brickbats, that
the hind leg of pterosaurs was an attachment point for the wing membrane.
In fact I think the greater success of birds in developing a much wider
range of body forms and lifestyles than either of the other two winged
groups may have a great deal to do with the fact that birds came up with a
flight mechanism that did not compromise the hind limbs (neither did
insects, for that matter, and look how successful THEY are).
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
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