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Re: BADD BCF



>>Even highly-evolved living gliders (which, as I have argued elsewhere on
>>this list, may not have anything to do with the origin of flight) often use
>>their gliding ability simply to get about, not just to flee predators; I
>>have seen this myself in Draco lizards and giant flying squirrels in Borneo.
>
>Yes, but as someone on this list once said, "evolution in gliders seems to
make better gliders."  Do any of the above species have what it takes to
evolve powered flight?
>
>Rob

The "someone" was me, I think, and as the above quote is also mine I suggest
that they are not contradictory!  It is not so much whether such species
have "what it takes" to evolve powered flight but whether there is any
selective pressure for them to do so.  I suspect that the gliding mechanism
in these species is so efficient and well-adapted to their environment (it
is amazing how many accomplished gliders live in southeast Asian
rainforests) that there would be no advantage (and perhaps  a disadvantage)
in trading it in for a much more energetically-expensive mechanism of aerial
locomotion.  A creature like a giant flying squirrel or a colugo that can
glide more than 100m with almost no loss in altitude has little need to fly
in a rainforest (the giant flying squirrel I saw in Borneo, at the Danum
Valley Research Centre in Sabah, apparently made nightly glides across a
fairly large river from its day roost into the forest - quite a thing to see
in the lat afternoon, especially as this species (Petaurista petaurista) is
mostly dark reddish and looks quite orange in the setting sun, and is about
80cm long including the tail.
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
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