So they don't eat their young? On Jul 20, 10:31 pm, archytas <[email protected]> wrote: > I'm working on a paper for a conference on Darwin - something of an > excuse for myself and two colleagues to have a Xmas drink together in > Portugal. The topic, at least in working form, is 'simplexity and > tropical fish realism'. One or two in here raise their spines, > stickleback fashion, whenever teleology raises its head. Orn has > fought them off long and hard - my thanks for that. I found this > whilst brushing up a bit on Darwinism via the Stanford Encyclopedia of > Philosophy on-line. The relevance to teleology is in the last line, > though I've left the rest in as we should all know some prawns are > colour-blind to red. > > To take one startling example, he was able to test and confirm a > hypothesis that a group of males, with a color pattern that matched > that of the pebbles on the bottoms of the streams and ponds they > populated except for bright red spots, have that pattern because a > common predator in those populations, a prawn, is color blind for red. > Red spots did not put their possessors at a selective disadvantage, > and were attractors for mates. (Endler 1983, 173-190) We may refer to > this pattern of coloration as a complex adaptation that serves the > functions of predator avoidance and mate attraction. But what role do > those functions play in explaining why it is that the males in this > population have the coloration they do? > > This color pattern is an adaptation, as that term is used in > Darwinism, only if it is a production of natural selection (Williams > 1966 261; Brandon 1985; Burian 1983). In order for it to be a product > of natural selection, there must be an array of color variation > available in the genetic/developmental resources of the species wider > that this particular pattern but including this pattern. Which factors > are critical, then, in producing differential survival and > reproduction of guppies with this particular pattern? The answer would > seem to be the value-consequences this pattern has compared to others > available in promoting viability and reproduction. In popular parlance > (and the parlance favored by Darwin), this color pattern is good for > the male guppies that have it, and for their male offspring. > (Binswanger 1990; Brandon 1985; Lennox 2002). This answer strengthens > the ‘selected effects’ or ‘consequence etiology’ accounts of selection > explanations by stressing that selection ranges over value > differences. The reason for one among a number of color patterns > having a higher fitness value has to do with the value of that pattern > relative to the survival and reproductive success of its possessors. > > Selection explanations are, then, a particular kind of teleological > explanation, an explanation in which that for the sake of which a > trait is possessed, its valuable consequence, accounts for the trait's > differential perpetuation and maintenance in the population. > > Now that the teleology question is settled, can anyone explain what > advantage to the prawns it is to be colour blind to red?
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