Assortative mating

Assortative mating (also called assortative pairing), and the related concept Disassortative mating, is the phenomenon where a sexually reproducing organism chooses to mate with individuals that are similar^[1][2] (positive assortative mating) or dissimilar (negative assortative mating or disassortative mating) to itself in some specific manner. In evolution, these two types of assortative mating have the effect, respectively, of increasing or reducing the range of variation (trait variance), when the assorting is cued on heritable traits. Positive assortative mating, therefore, results in disruptive natural selection, and negative assortative mating results in stabilized natural selection.

It is mirrored by selective fertilization in plants.

General characteristics

Assortative mating has been invoked to explain sympatric speciation. For some populations there are two different resources for which different phenotypes are optimum. Intermediates between these two phenotypes 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.

Humans

In humans, genetic counseling can lead to a strategy of negative assortative mating.^{[citation needed]} Assortative mating among computer scientists with Asperger syndrome could be contributing to the rise in juvenile autism spectrum disorders in Silicon Valley.^[2] Homogamy is marriage based on assortative mating.

Goby fish

Positive assortative mating is believed to be the cause of the speciation of a daughter species from the parent species of coral-dwelling goby fish. The species live in a small area of rare coral in the ocean around Bootless Bay in southern Papua New Guinea which the parent species shun. 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. The speciation in the early stages would depend on assortative 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.^[3]

Footnotes

1. ^ Armstrong, John B. (1997). The Argument for Assortative Mating. Originally published on the website of The Canine Diversity Project, retrieved January 30, 2011: „Assortative mating is the mating of individuals that are phenotypically similar.“
2. ^ ^{a b} Silberman, Steve (2004). The Geek Syndrome. Wired.com, retrieved January 30, 2011: „(...) assortative mating is the blond gentleman who prefers blondes; the hyperverbal intellectual who meets her soul mate in the therapist's waiting room.“
3. ^ 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.

References

See also

• Disassortative mating
• Intra-species recognition
• Koinophilia
• Balancing selection
• Directional selection
• Disruptive selection
• Negative selection (natural selection)
• Hypergamy