[Taxacom] Toba extinction and orangutans

[John Grehan]

I also saw the same program and naturally the same consequences came to
my mind. As a biogeographer I have often thought about distribution and
survival in relation to actual or catastrophic events. What I have
noticed is that some tectonically very precise distributions persist in
areas that are supposed to have experienced catastrophic impacts (such
as asteroid hits in Central America) and I sometimes wonder whether
local survival (at least in the general vicinity) is greater than one
might think from the speculations that focus on the environmental
degradation. I suspect (and it's only my imagination) that life
generally survived in Sumatra and the surrounding areas although local
extinction, and extinction of localized taxa would no doubt have
occurred.

As an anecdote, I recall that local endemics of some insects are found
near the Taupo Crater in New Zealand (this was one of the other super
volcanoes sites mentioned) and it has been suggested that they survived
despite their proximity to the volcano because a lot of material was
blasted out horizontally, so fast that some forests survived on the
leeward slopes of nearby mountains. That might be a load of old crock so
I am happy to be corrected on that one. By the way, Lake Taupo is about
40 km in its greatest length and almost 30 km wide. 

John Grehan


> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Ken Kinman
> Sent: Tuesday, September 26, 2006 10:21 PM
> To: taxacom at mailman.nhm.ku.edu
> Subject: [Taxacom] Toba extinction and orangutans
> 
> Dear All,
>       I was watching NOVA tonight about the megavolcanic eruption of
Toba
> ca. 71,000-74,000 years ago.  It is known to have caused a large
> bottleneck
> in the genetic diversity of humanity way over in Africa.  The
> deforestation
> of much of southeast Asia would probably have wiped any orangutans in
> Sumatra, Borneo, or even the adjacent mainland.  I just wonder---how
far
> away the surviving populations of orangutans would have had to have
been.
> Perhaps Burma or even India?
>     The genetic bottleneck for orangutans must have been even greater
than
> it was for humans.  So it occurred to me that this could conceivably
> complicate the genetic study of great ape evolution.  Not that it
> convinces
> me one way or the other, but it certainly is worth considering.
>    ----Cheers,
>           Ken Kinman
> 
> 
> 
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