|
Assortative mating is when sexually reproducing organisms tend to mate with individuals that are like themselves in some respect. In evolution, assortative mating has the effect of expanding the range of variation.
Assortative mating has been invoked to explain sympatric speciation. For some populations there are two different resources for which different genotypes are optimum. Intermediates between these two genotypes are less favorable. It is then favourable if the organisms can recognize mates that are optimized for the same resources as they are themselves. If mutations that make such recognition possible appear, these will be selected for.
For example, Munday et al. (2004) note the speciation of a daughter species from the parent species of coral-dwelling goby fishes that live in a small area of rare coral that the parent species shuns in the ocean around Bootless Bay in southern Papua, New Guinea. The daughter species has become reproductively isolated from the parent species even though the parent species surrounds the daughter species so there is no geographic isolation. According to Munday, the speciation in the early stages would depend on assortive mating in which the evolving goby fishes would prefer to mate with other fish that preferred to spawn in the same area of rare coral.
Another example of assortative mating is when humans tend to mate with individuals who are like themselves, regarding intelligence or stature. With humans there is at least a small correlation between mates for almost any trait that has been studied.
References
Munday, Philip L., Lynne van Herwerden, and Christine L. Dudgeon. 2004. "Evidence for sympatric speciation by host shift in the sea." Current Biology 14 (16), pp. 1498-1504.
See also
|
