NW: Will a straightened-out mollusk taxonomy at the NIH get the Chesapeake Bay cleaned up? Those of us who like fried clams just don't get concerned by their pedigree.
DC: It might help in a couple of ways. Are those clams legally harvested and are they really clams? Cut-up bits of meat are not distinctive morphologically, but molecular analysis plugged into an accurate genetic database can identify the source of meat. This was actually done in a study of whale meat marketed in Japan. Not all of it was what it was supposed to be. Evolutionary data can tell us which species are likely to be confused. Molecular data for these species can help us identify other specimens that are not morphologically distinct, such as very young juveniles. This enables easier study of life history dynamics. In turn, this will allow better fisheries management. Taxonomy and evolution of molluscan parasites has shown that the major pests of Chesapeake Bay oysters were introduced when someone tried to grow Pacific oysters over here. Knowledge of evolutionary relationships can point to other introductions that would probably be a really bad idea.
NW: Viruses, "biotic" or otherwise, are strange little creatures, and while their mutations are a fascinating and important subject, I would find their use as a model for the microevolution of bacteria, let alone the macroevolution of vertebrates, highly suspect. I mean, how "handicapped" could a mutant virus BE?
DC: A virus has to be able to invade its host and replicate there. If it cannot do that, it is fatally handicapped. However, they certainly have fewer vital functions than bacteria or eukaryotes. Viruses, especially RNA viruses, have extremely high mutation rates and so their evolution is easier to study than in organisms with longer intervals between generations and less rapid change. However, the mutation and reproduction rates in bacteria allow study of the evolution of cultures in the lab. Of course, they also face very different selective pressures than do vertebrates. Viruses thus provide useful models of molecular evolution, but not much help regarding morphological evolution.
NW: What you say is true and logical, but I have heard many of today's evolutionists claim that the division between artificial selection and natural selection is, well, artificial. If the individual has certain traits, if lives (and multiplies); if it doesn't it dies. That is what good ol' Sagan called his "proof" of the "fact" of evolution in his Cosmos series, and it's one of the thorn's in the side of many of us concerning the typical presentation of evolution.
DC: The definition of evolution is key here. Examination of the fossil record shows that organisms have changed over time, and, at a smaller scale, historical observations show the same thing. Thus, some evolution has indeed occurred, and may be properly called the fact of evolution. The means by which these changes have taken place, and the extent of the evolutionary connections between organisms, are the subject of ongoing study. Natural selection and genetic drift acting on the variations produced by mutations provides a good explanation of quite a lot of the history of life, but we certainly do not know all that there is to explain, much less have explanations for everything.
NW: Thanks for your reply.
DC: You are welcome. Hopefully this has us all more on the same wavelength.
Dr. David Campbell
Old Seashells
46860 Hilton Dr #1113
Lexington Park MD 20653 USA
bivalve@mail.davidson.alumlink.com
That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droigate Spa
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