(February 12, 2011 at 8:12 am)Zen Badger Wrote:(February 12, 2011 at 4:33 am)Chuck Wrote: A fact that might surprise you - bacteria has extremely limited ability to undergo Darwinian evolution and speciation for a reason too simple yet to profound for any Christian fundamentalist to grasp, which is why they have not yet latched on to this fact as a basis for a spurious argument against evolution. This is also an argument against the prevalence of complex life in the universe.
And what is that reason? I am agoghock:
Darwinian evolution and speciation requires that traits offering survival advantage be heritable. If an advantageous trait is lost with the death of it's possessor, then there is no evolution. If advantageous traits are not passed preferentially to the possessor's descendants, but are instead spread directly to other members in the same community, then there is no speciation.
As it turns out, unlike more complex nucleated cells, members of bacteria communities liberally passes their genes between each other in addition to passing them to their own descendants. As a result, a bacteria that possesses an advantageous gene may not pass it onto it's own descendants because it may swap this advantageous gene for an indifferent gene from a different member. So to an individual bacteria living in a community, advantageous genetic traits are not heritable in any sense specific to it's own genetic lineage. In fact, it has no real defined genetic lineage. Furthermore, because bacteria pass genes around, those in temporary possession of advantageous genes do not tend to collective lineage distinct from those who are not in possession of it. So there is no speciation.
How bacterias evolve, indeed whether it is meaningful to apply to bacteria the same taxonomical framework as complex life, is a point of debate in modern biology. Suffices it to say bacteria genetics puts a huge gulf between them and higher complex cells that is not easy to bridge.
