BIOL 1051 Lecture Notes - Lecture 12: Sympatric Speciation, Reproductive Isolation, Allopatric Speciation
Document Summary
Biological species concept: species are populations of organisms that could interbreed with each other but cannot interbreed with other organisms; cannot be applied in all situations (ex. With fossils and asexual organisms); the liger is not considered a species. Species relies on the ability to reproduce, not the similarity in appearance. If individuals of 2 different species try to mate, not fertile offspring will be produced; barriers block the exchange of genes between species and allow them to evolve independently; barriers keep species reproductively isolated from each other; Individuals are physically unable to mate with each other; or, if individuals are able to mate, the male"s reproductive cell is unable to fertilize the female"s reproductive cell; these are called prezygotic barriers. Matings produce hybrid individuals that do not survive long after fertilization; if a hybrid offspring survives, they are infertile or have a reduced fertility (ex. A mule- cross between donkey and horse); these are called postzygotic barriers.
