As I understand it, it isn't that you can't observe some change with very small organisms, its that you have a big problem with small populations of large organisms producing enough beneficial mutations at the rate required.That's a minor problem compared to the one identified by the Nobel Prize-winning geneticist Susumu Ohno. In his classic book Evolution by Gene Duplication he pointed out that in order for a gene to evolve some new function, the gene would first need to be replicated lest the organism lose the gene's original function. The replicate gene can then mutate to generate the new function. But since that gene is no longer expressed, it is no longer subject to selection pressure and thus is likely to be lost. Natural Selection is an efficient mechanism for deleting "unnecessary" genes.
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Wednesday 7th December 2016 00:36 GMT Pompous Git