Non - Non-homology via homologous genes Summary of problems...

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Non-homology via homologous genes Summary of problems with claim: The basic problem with this claim, as with the one before, is it relies on a fabricated simplistic assumption, a strawman, that, "[a]ccording to neo-Darwinian theory, the development of non- homologous structures should be regulated by non-homologous genes." (pg. 44) Full discussion: Explore Evolution presents this example: Consider, for instance, the eyes of the squid, the fruit fly, and mouse. The fruit fly has a compound eye, with dozens of separate lenses. The squid and mouse both have single-lens camera eyes, but they develop along very different pathways, and are wired differently from each other. Yet the same gene is involved in the development of all three of these eyes. EE , p. 44 Darwin admitted the evolution of a structure as complex as the eye was difficult, but not impossible, to imagine. Darwin hypothesized that a complex eye could develop through a gradual transition from some type of prototype or simple eye. In fact, anatomists have discovered numerous intermediates between the more primitive prototype and the vertebrate eye. The full range of transitional structures has been observed within living snails (see Salvini-Plawen and Mayr, 1977, "On the evolution of photoreceptors and eye," Evolutionary Biology 10:207-263). If indeed the vertebrate eye developed from intermediates found in other groups, wouldn’t we expect to find some of the same genes involved in the organization of these structures? At the developmental level, according to Carroll, both the mouse Pax6 and the fruit fly ortholog eyeless are involved in regulatory networks that direct eye development. It is therefore not surprising that we find the same gene involved in eye morphogenesis, even when the general morphology of the eye shows variation. The ancestor of insects and vertebrates would have had light sensitive organs of some sort, and some regulatory gene would have controlled the development of such structures. That gene is a shared, derived trait uniting many groups of animals, including insects and vertebrates. From that ancestral population, one group went on to produce the compound eyes associated with insects, a
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This note was uploaded on 11/08/2011 for the course BIOLOGY BSC1086L taught by Professor Leostouder during the Fall '10 term at Broward College.

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Non - Non-homology via homologous genes Summary of problems...

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