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Re: Pleistocene/Holocene extinctions



--- David Marjanovic <david.marjanovic@gmx.at>
schrieb:

> > Australia - probably mainly human-altered fire
> regime
> > (and other ecological changes) since Latest
> > Pleistocene, some hunting, end of ice age was only
> > coup de grace.
> 
> Didn't the extinction happen more like 40,000 years
> ago, even before the 
> Last Glacial Maximum?

Started then, did not finish until after 30KABP. In
some cases, long afterwards (thylacine)
 
> (And what does MVP mean?)

Minimum viable population. How many reproducing
individuals are needed so that the population is safe
from extinction through intrinsic factors (namely
inbreeding depression) "infinite" time

> > End of ice age for example seems to
> > have been a factor in thylacine disappearing from
> > mainland,
> 
> Didn't that happen several millennia later?

Finish yes, but it must have started >>10KABP

> The rainforest was, however, considerably less
> fragmented than was assumed 
> 10 years ago.

True - like I said, the data we have gives probably a
misleading picture at face value. Much to be found out
here.

> > * Long time to maturity, not even close to
> panmixia.
> > Deleterious alleles must have been a dime a dozen
> in
> > mammoths.
> 
> Can hardly have been much worse than with the
> surviving elephants, can it? 

On a purely genetic basis, certainly. The crucial
question is: how would a mammoth (which was presumably
fairly naive as regards predators, having 1 to maybe a
handful of taxa - Amur tiger and possibly bears -
which could prey on it* cope with the arrival of (by
then) quite sophisticated tool-using pack hunters?

We know that Asian elephants didn't fare all too well;
their historical range is maybe half of the
prehistoric one (which reached to Syria - the
controversial "Crete Mammoth" paper found - in its
not-controversial-at-all part - hints of a smattering
of ghost lineages between the W and the E extents of
_E. maximus_ prehistoric range). Not just human
hunting to blame, but still.


Eike

* tentatively - have I forgotten some Siberian apex predator?


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