Laboratory populations

Laboratory populations - genetic architecture of speciation...

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Laboratory populations might serve as model systems. One can establish the conditions of the specific model under question and ask if the predicted divergence is observed. Mathematical models can address specific predictions about modes of speciation. Both of these "artificial" methods are important since they can identify what is possible . Knowing what's possible might spur one on to looking for it in unexpected contexts in natural populations. With the use of molecular tools the comparisons of intraspecific and interspecific genetic variation has been studied in some detail. Aim is to identify genetic changes during speciation . These data show us that genetic change is associated with speciation. We want to be able to describe the genetics of speciation and the genetics of species differences . To do so we need to distinguish genetic changes that cause speciation from those that accompany speciation . These will differ a lot from one group of organisms to the next and will depend on the
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Unformatted text preview: genetic architecture of speciation. Best data on both of these issues have come from the many species of Drosophila Coyne and Orr (1989, Evolution vol. 43, pg. 362-381) take Ayala's approach one step further and attempt to correlate genetic distance (Nei's D) with amounts of prezygotic and postzygotic isolation. In the literature there are many reports of the amount of genetic distance between closely related species of Drosophila and the amount of reproductive isolation between many of the species for which genetic distance has been measured ( premating or prezygotic isolation is measured as [1-(proportion of heterotypic matings/proportion of homotypic matings)] which ranges from - infinity for all heterotypic (between species) matings to 0 for random mating to +1 for all homotypic matings. Rarely do two species prefer to mate with the wrong type so the index effectively ranges from 0 to 1)....
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