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Speciation160-page6 - Speciation can occur with little or...

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Methods of Speciation - 6 Behavioral Isolation Mating behavior, as we have discussed is crucial to successful reproduction in a number of species. Individuals do not recognize courtship patterns or signals from members of populations different from their own will have behavioral isolation. Behavioral isolating mechanisms include: Visual clues -- patterns and physical movements Audio clues Chemical clues, such as pheromones Pollination attractants Mechanical Isolation (Mechanical Incompatibility) There may be physical differences in structure or function of the reproductive organs that prevent copulation between members of different populations, or in the case of some plants, flower shapes that prevent some pollinators from visiting. The domestic turkey has been bred for large breasts to the point that copulation is "impossible". Many Hawaiian fruit flies have copulatory structures that are of different sizes. Flower Shape and Pollinators Snails and Coil Shape Anatomical Change and Speciation
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Unformatted text preview: Speciation can occur with little or no anatomical change in organisms. If the organisms do not reproduce, they are biologically different species. Similarly, change in appearance within a species is a natural process and may not lead to speciation in the absence of any isolating factors. Such isolation factors can be random events or the result of natural selection. Maintaining Reproductive Isolation Ultimately in order for new species to form, the separation of gene pools by geography, ecology, genetics or behavior, must be accompanied by or followed by reproductive barrier so that interbreeding is not possible, even if the gene pools were to be mixed again. Reproductive isolating mechanisms may prevent successful fertilization (pre-zygotic or pre-mating) or successful development (post-zygotic or post-mating). The isolation mechanisms just discussed of geography, time, behavior and structure are pre-zygotic reproductive mechanisms....
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