The genes just seem too stable over long periods of time. Take sharks or crocodiles, pretty much the same organisms, if not exactly the same, for eons. Why aren't they eventually displaced by a daughter species that has developed some sort of competitive advantage. Isn't that how NS is supposed to work?
For all we know this has already happened. Morphology is not a good indicator of reproductive isolation. The fact that modern Crocodilia resemble their fossil ancestors does not neccessarily mean that they would be interfertile. Large scale morphological changes are the crudest and largest scale effects of genetic change, there is a vast ocean of molecular evolution that we may never be able to properly explore and any number of physiological rather than morphological factors that might lead to reproductive isolation between two crocodiles millions of years apart.
The accumulation of mutations will not suddenly lead to the animals being a new species in one leap overnight when they reach some critical point, but they will be a new species in relation to their ancestor of million of years before.
TTFN,
WK
This message has been edited by Wounded King, 02-25-2005 04:57 AM
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