Re: Metabolism may explain fossils vs. genes evolution mismatches

[Michael Habib <mbh3q@virginia.edu>]

Taking the effect into account is not all that easy, even if you know it
exists.  There is no known expression relating the metabolic effect to clock
rates.  Furthermore, it's hardly precise or well supported for most groups.
In fact, the metabolism link is likely somewhat misleading: species with
high metabolisms have, much of the time, short generation times.  All rates
of change associated with evolving populations (be it drift, mutation,
selective effects, etc) occur on a generational clock.  However, we insist
on using years, and so those organisms with short doubling times end up with
rapid rates of evolution and selective response.

However, the test cases for mammals have not always worked out very well,
and I believe arthropods are somewhat sticky as well.


> 
>>> Now it's clear why nematodes etc. evolve so fast!
>> 
>> Not to me.
> 
> They're very small, except for a few parasitic ones.


I agree the reason is still not clear.  It's also not clear that they
actually evolve that quickly as a general rule.  They have high diversity,
but the time since origin is only broadly known (and the estimates are
generally very old).

Cheers,
--Mike Habib