Editing Assortative mating (section)

== Causes ==
[[File:Scarlet lily beetle lilioceris lilii.jpg|thumb|right|240px|[[Leaf beetle]]]]
Several hypotheses have been proposed to explain the phenomenon of assortative mating.<ref>{{cite journal |first1=Yuexin |last1=Jiang |first2=Daniel I. |last2=Bolnick |first3=Mark |last3=Kirkpatrick |year=2013 |title=Assortative mating in animals |journal=The American Naturalist |volume=181 |issue=6 |pages=E125–E138 |doi=10.1086/670160 |pmid=23669548 |bibcode=2013ANat..181E.125J |hdl=2152/31270 |s2cid=14484725 |url=https://repositories.lib.utexas.edu/bitstream/2152/31270/1/AssortativeMatingInAnimals.pdf |hdl-access=free }}</ref> Assortative mating has evolved from a combination of different factors, which vary across different species.<ref>{{cite journal |first1=Yuexin |last1=Jiang |first2=Daniel I. |last2=Bolnick |first3=Mark |last3=Kirkpatrick |year=2013 |title=Assortative mating in animals |journal=The American Naturalist |volume=181 |issue=6 |pages=E125–E138 |doi=10.1086/670160 |pmid=23669548 |bibcode=2013ANat..181E.125J |hdl=2152/31270 |s2cid=14484725 |url=https://repositories.lib.utexas.edu/bitstream/2152/31270/1/AssortativeMatingInAnimals.pdf |hdl-access=free }}</ref>

Assortative mating with respect to body size can arise as a consequence of intrasexual competition. In some species, size is correlated with fecundity in females. Therefore, males choose to mate with larger females, with the larger males defeating the smaller males in courting them. Examples of species that display this type of assortative mating include the [[jumping spider]] ''[[Phidippus clarus]]'' and the [[leaf beetle]] ''[[Diaprepes abbreviatus]]''.<ref>{{cite journal | last1 = Hoefler | first1 = Chad D. | year = 2007 | title = Male mate choice and size assortative pairing in a jumping spider, Phidippus clarus | journal = Animal Behaviour | volume = 73 | issue = 6| pages = 943–954 | doi=10.1016/j.anbehav.2006.10.017| s2cid = 53197198 }}</ref><ref>{{cite journal | last1 = Haran | first1 = Ally R. | last2 = Handler | first2 = Alfred M. | last3 = Landolt | first3 = Peter J. | year = 1999 | title = Size-assortative mating, male choice and female choice in the curculionid beetle Diaprepes abbreviatus | journal = Animal Behaviour | volume = 58 | issue = 6| pages = 1191–1200 | doi=10.1006/anbe.1999.1257| pmid = 10600139 | s2cid = 11680456 }}</ref> In other cases, larger females are better equipped to resist male courtship attempts, and only the largest males are able to mate with them.{{citation needed|date=October 2017}}

Assortative mating can, at times, arise as a consequence of social competition. Traits in certain individuals may indicate competitive ability which allows them to occupy the best territories. Individuals with similar traits that occupy similar territories are more likely to mate with one another. In this scenario, assortative mating does not necessarily arise from choice, but rather by proximity. This was noted in western bluebirds although there is no definite evidence that this is the major factor resulting in color dependent assortative mating in this species.<ref name=Jacobs>{{cite journal | last1 = Jacobs | first1 = Anne C. | last2 = Fair | first2 = Jeanne M. | last3 = Zuk | first3 = Marlene | year = 2014 | title = Coloration, Paternity and Assortative Mating in Western Bluebirds | journal = Ethology| volume = 121 | issue = 2| pages = 176–186 | doi=10.1111/eth.12327}}</ref> Different factors may apply simultaneously to result in assortative mating in any given species.{{citation needed|date=October 2017}}