Re: crocs eating hadrosaurs (was Gr. 9 sci proj)

[John Bois <jbois@umd5.umd.edu>]

Tony Canning wrote:

> > Since mammals don't have the same fecundity problems as
> > dinos (after all, they only have to have one offspring to maintain
> > populations)...

> Unless I've misunderstood what John is saying, this seems to be looking
> at mammalian fecundity the wrong way round - surely mammals don't
> have small numbers of young because that is sufficient to maintain
> the population; this sounds like group selection theory which is impossible
> to justify.   Mammals have small numbers of young because of the obligate
> parental investment required, both before and after birth.

Tony, I'm sorry, this is my second attempt to clear this up.  What I 
_said_ does sound group selectionist.  What I _meant_ was that predation 
levels are so low that low fecundity is sufficient to keep populations at 
carrying capacity.  A dinosaur, on the other hand, possibly had to 
produce more offspring in order for an equivalent number to survive in a 
similar niche.  I suppose both of these strategies are valid (but see my 
response to Bruce Thompson).