Mike the Mad Biologist has a post up, A Biologist Confuses Artificial and Natural Selection:
There's a really interesting article in last week's NY Times magazine about global warming and the spread of weeds.... ...Artificial selection occurs when the fitness criterion--that is, what trait or phenotype will have higher survivability or reproductive output--is directly chosen by the experimenter. In the case of the weeds, if we were delibrately trying to grow better weeds--that is, mowing down rice biovars that aren't sufficiently 'weedy'--that is artificial selection. Simply changing the environment such that weedy biovars will do better is natural selection because we are not specifically trying to enrich for rice that have the trait of 'weedy-ness.' Keep in mind that one can use natural selection for very applied purposes, and the boundaries will get fuzzy, but in the case of global warming, this is clearly natural selection. Besides, in a materialist sense, we are just another species of critter.
Obviously, context matters. That being said,
count me as in the group which is mildly skeptical of distinctions between artificial, natural, sexual and social selection.
I think the distinctions reflect systematic differences between these forms of selection, but I also think that they are themselves somewhat artificial insofar as the fundamental dynamic is the same, and the semantic separation has a tendency of deemphasizing this. Remember that Charles Darwin was influenced by the insights derived from the cultivation of plants and breeding of animals. In particular I think that the artificial vs. natural selection distinction has a strong dose of homocentrism embedded within it as a background assumption. I'm not opposed to homocentrism, but there is normative baggage which undergirds it which does not hold when one contrasts selection with random genetic drift. Of course, the term random genetic drift itself reflects biocentrism, as it is nothing more than a particular manifestation of sample variance. In the end my attitude toward most of these definitions is guided by instrumental calculations. I happen to believe that breaking the distinction between artificial and natural selection has a positive yield in terms of insight as to the role of selection as a general evolutionary process, while a term such as random genetic drift has a specific and precise clarity which sample variance may not.
