Natural Selection and what it didn\'t do for dogs... (Evolution)

by David Turell , Monday, January 25, 2010, 19:12 (5414 days ago) @ xeno6696

David,
> 
> If I understand your position:
> 
> 1. The actual cause of genetic variance is mutation--mutation plays a more significant role in speciation than genetic recombination? -All changes in DNA coding play a role by whatever mechanism they appear, as previously listed. Point mutation is just one of the ways. 
> 
> 2. Natural selection only operates via an exterior event. -Yes 
> 
> Why do you think that sexual recombination itself couldn't uncover most of these "mutations?" Take the common ancestor of man and chimps. Whatever this thing was, it had the ability to both become man and chimp. However, the circumstances that lead our paths to diverge could only come about via some kind of selection. I hope I'm talking clearly...-You are clear. Selection is the matching of some varient to the natural challenges, and of course it plays a major role in evolution. But underlying variation in a species is a necessary precursor to a selection process. Species have disappeared because there was not enough variation to overcome the sudden environmental challenges. Changes in DNA come because of random mutation but also the other mechanisms that have been more recently discovered as previously listed in part.-The sexual form of reproduction certainly allowed more variation and more diversity of species than either parthenogenesis or simple binary fission. It undoubtedly sped up evolution on a time basis. Sex allowed mutations in both sexes to be in play, increasing the chances for change by mutation to be doubled. How sexes appeared is another mystery.