From: CurtAdams@aol.com
Date: Sat Nov 20 1999 - 17:09:02 MST
In a message dated 11/20/99 3:55:57 PM Pacific Standard Time, jr@shasta.com
writes:
> Now, if mice suddenly mutated (or got genetically engineered) so that they
could
> live 200 years and grow as big as elephants, should we expect them to do
so in
> large numbers, in the wild? Or would something in their natural environment
> interact with the Uber-Mice in such a way as to reduce rather than increase
> their numbers? --J. R.
Longer lifespan with no disadvantages would be selected for, roughly to the
point where only a negligeable number of mice would survive that long due to
other causes (a lot less than 200 years, I'd think). If the effects of the
gene are more complex (only works if a particular set is in the organism,
useless or harmful otherwise) then selection is less reliable, hence weaker
and the effect "gives out" earlier.
Of course longer lifespan may have costs. In the Rose lab, the long-lived
strains take longer to develop and lay fewer eggs in the first part of life.
Big size can be either good or bad, so it's hard to say in general. Big as
an elephant would, I think, be very bad. Little mice are doing very well
while the only land animal as big as an elephant (the elephant :-) will be
extinct in the wild in a few decades if humans don't save the ranges.
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