ANT 1 Lecture Notes - Lecture 7: Species Problem, Sympatric Speciation, Allopatric Speciation
Document Summary
Species concept = a way of defining a species. Many proposed, but these two are the most common: Species = group of organisms bound by selection pressures that are distinct from pressures on other groups. Biological species concept: reproductive isolation maintains phenotypic differences between groups. Gene flow (aka migration) the movement of genes between groups. Biological species concept: barriers to gene flow. Natural selection (sometimes differences exist despite gene flow) How does speciation occur: allopatric speciation (allo = other , patria = homeland , sympatric speciation (sym = same , parapatricspeciation (para = beside ) Original population is split by some type of geographic barrier that prevents gene flow. Differing environments select for different phenotypes in these isolated populations: different environments = different adaptations o genetic drift may also lead to differentiation. Eventually, if the conditions persist, the isolated populations will diverge enough to be considered different species. Selection favors two different adaptations (physical or behavioral) to the same environment.
