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Speciation

Speciation. Species A population that interbreeds and does not breed with other populations even when there is opportunity to do so Speciation The formation of new species. Modes of Speciation (How it Happens). 1. Allopatric Speciation

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Speciation

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  1. Speciation

  2. Species • A population that interbreeds and does not breed with other populations even when there is opportunity to do so • Speciation • The formation of new species

  3. Modes of Speciation (How it Happens) • 1. Allopatric Speciation • Involves the geographic separation of a population of organisms • Happens most often • Eg. A road is built or a mountain range forms • Steps: • Populations are exposed to different environments, so different adaptations • Genetic drift and mutations occur in each group. This widens differences in the gene pool • Interbreeding does NOT occur • Therefore, genetic isolation and two new species

  4. 2. Sympatric Speciation • Occurs WITHOUT geographic isolation • There are two kinds • A) Hybridization • Parents can produce offspring with a different number of chromosomes than them • They are immediately reproductively isolated form their parental species • However, if they can reproduce within themselves (eg. Plants), they may be able to compete with the parental species • B) Disruptive Selection • Recall: both extremes are selected while intermediates are eliminated • The two varieties may continue to diverge to the point that they don’t interbreed

  5. In any type of speciation the key is maintaining GENETIC ISOLATION: • Do not allow interbreeding of two different groups

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