GENETICS OF SPECIATION - identify important features that...

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GENETICS OF SPECIATION Speciation has occurred, is occurring and will occur. These are undeniable facts. The problem is: How do we study speciation? There is no single approach since there is no single mechanism by which species speciate. Some approaches used in the past: Study patterns of morphological change in the fossil record in a well defined lineage of organisms. Success depends on many unknowns: stratigraphic resolution (will you "see" the speciation event); distinguishing geographic variants from true species (all you have is morphology. Comparisons of closely related species . These have speciated recently (assuming closely related ~ short time since speciation) so careful studies of their biology may
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Unformatted text preview: identify important features that contribute to reproductive isolation. Study intraspecific variation . Look for evidence of incipient barriers to gene exchange. Perform crosses between individuals from different regions; look for differences in genital morphology, secondary sexual characteristics. These may show some bimodal distribution suggestive of early steps in evolution. Must ask: what might we expect to find? This depends entirely on the model of speciation that might apply to the organism under study. Looking within a large species range for signs of variation may be fruitless if the speciation mode is peripatric with genetic revolutions?...
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