Saturday, August 25, 2012

Incredible New Photographs of Live Coelacanths

Yes, there are a hundred coelacanth species, from dozens of genera, from a half dozen families, grouped into at least two suborders fitting into the order Coelacanthiformes. The taxonomic equivalent for dogs is the order Carnivora. Do you really wish to make a claim roughly equivalent to claiming that bears, badgers, and bobcats could all be due to variety existing in the same Carnivora genome? Keep in mind that Carnivora is only a little more than one-tenth the age of Coelacanthiformes, yet genetic basics like chromosome number can be wildly different. Just within family Ursidae the giant panda has 42 chromosomes, the spectacled bear 52, and the grizzly 74. From this comparison then it is a good bet that the coelacanth genomes of today are quite different from what existed 360 million years ago.

You're a bit muddled in your terms. Darwinian evolution is a collection of ideas which in Darwin's time didn't include mutation. He knew that species change over time, he knew that every group of organisms descended from a common ancestor, he knew that species multiplied by splitting into daughter species, he knew that speciation occurs through gradual processes rather than by saltation (sudden emergence of representatives of a new type), and he gave us one of the mechanisms of evolution: natural selection. Darwin didn't know the origin of new genetic information: mutation. In fact the merging of genetics and natural selection into the neo-Darwinian synthesis didn't happen until around 60 years after Darwin died. You're not getting genetic drift [wikipedia.org] right either.

It is completely accurate to say that the only way species don't evolve is if they go extinct. At the most basic level evolution is simply the change in allele frequency in a population over time. Get a mutation, the allele frequency changes. Natural selection kills something off, ignoring clonal populations that's a change in allele frequency. Whether or not a change is necessary for survival is looking at it wrong. After all, other members of the species are getting along just fine without some specific mutation. A better way of looking at it is to ask if the mutation is compatible with survival. Does the mutation result in a nonviable organism? That's bad. Does it do nothing? Fine. Does it give you an advantage under some or all situations? That's good and as a result you might get more offspring and over time produce a large shift in allele frequency. These changes brought about by mutation and selection (and other evolutionary mechanisms) build up over time and new species inevitably result. There's nothing religious about it.

Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/ywWAIPTMlE4/incredible-new-photographs-of-live-coelacanths

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