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Re: copes law



Nick Longrich wrote:
> 
>         Seems to me that at least part of this might have something to do
> with the nature of mass extinction. Big animals were hit especially hard
> by the KT event. With all those niches open for big things, of course
> mammal lineages would tend to increase in size.  Whether a similar pattern
> is observed in other extinctions or local extinctions, I don't know. It
> might just be that big animals are more vulnerable to extinction. There
> are fewer of them which means that they have less genetic variation, less
> chance of surviving in high-mortality events, and repopulate more slowly.
>         It would be interesting to know if bigger species are more
> vulnerable to extinction. Many big animals have seen significant reduction
> in numbers through part or all of their ranges- bison, cheetahs, tigers,
> wolves, elephants, rhinos, sea otter, elephant seal, condor, most big
> species of whales. Certainly the big animals really bought it hard in the
> last extinctions. Of course, we pay more attention to the plight of a
> rhino than that of a mouse or a beetle. There are probably many more
> endangered small species, what would be good to know is whether a higher
> percentage of big animals are endangered or go extinct. Of course, humans
> are implicated in most or all of these events, so the application of
> recent times to prehistory may not work.

This is an interesting observation, just wish I knew how to test it.  However, 
 the mention of the cheetah brings up a couple of comments of my own.  
Contrary to popular belief, the cheetah is most likely dieing out not directly 
to man's influence but by their own inability to adapt.  You mentioned lack of 
genetic variation... YOU WIN!  They don't have much and simply have no room to 
adapt to any of the many changes that have taken place in their niche.  They 
went down that road of extreme specialization and have crashed against an 
immovable wall.
Related point:  could this have been a big factor in the dinos death?  I don't 
buy the asteroid theory except maybe as a contributing factor, but surely not 
the only reason.

Joe Daniel

jdaniel@aristotle.net