Editing Assortative mating (section)

== Effects ==
Assortative mating has reproductive consequences. Positive assortative mating increases genetic relatedness within a family, whereas negative assortative mating accomplishes the opposite effect. Either strategy may be employed by the individuals of a species depending upon which strategy maximizes fitness and enables the individuals to maximally pass on their genes to the next generation. For instance, in the case of eastern bluebirds, assortative mating for territorial aggression increases the probability of the parents obtaining and securing a nest site for their offspring. This in turn increases the likelihood of survival of the offspring and consequently fitness of the individuals.<ref name=Jacobs/> In birds whose coloration represents well being and fecundity of the bird, positive assortative mating for color increases the chances of genes being passed on and of the offspring being in good condition. Also, positive assortative mating for behavioral traits allows for more efficient communication between the individuals and they can cooperate better to raise their offspring.{{citation needed|date=October 2017}}

On the other hand, mating between individuals of genotypes which are too similar allows for the accumulation of harmful recessive alleles, which can decrease fitness. Such mating between genetically similar individuals is termed inbreeding which can result in the emergence of autosomal [[recessive disorders]]. Moreover, assortative mating for aggression in birds can lead to inadequate parental care. An alternate strategy can be disassortative mating, in which one individual is aggressive and guards the nest site while the other individual is more nurturing and fosters the young; however, this risks the breakdown of coadapted gene complexes, leading to [[outbreeding depression]]. This division of labor increases the chances of survival of the offspring. A classic example of this is in the case of the [[white-throated sparrow]] (''Zonotrichia albicollis''). This bird exhibits two color morphs – white striped and tan striped. In both sexes, the white striped birds are more aggressive and territorial whereas tan striped birds are more engaged in providing parental care to their offspring.<ref>{{cite journal | last1 = Horton | first1 = BM | last2 = Hauber | first2 = ME | last3 = Maney | first3 = DL | year = 2012 | title = Morph Matters: Aggression Bias in a Polymorphic Sparrow | journal = PLOS ONE | volume = 7 | issue = 10| page = e48705 | doi=10.1371/journal.pone.0048705 | pmid=23119092 | pmc=3485354| bibcode = 2012PLoSO...748705H | doi-access = free }}</ref> Therefore, disassortative mating in these birds allows for an efficient division of labor in terms of raising and protecting their offspring.{{citation needed|date=October 2017}}

Positive assortative mating is a key element leading to reproductive isolation within a species, which in turn may result speciation in sympatry over time. [[Sympatric speciation]] is defined as the evolution of a new species without geographical isolation. Speciation from assortative mating has occurred in the Middle East blind mole rat, cicadas, and the European corn borer.{{citation needed|date=October 2017}}

Like other animals, humans also display these genetic results of assortative mating. What makes humans unique, however, is the tendency towards seeking mates that are not only similar to them in genetics and in appearances, but those who are similar to them economically, socially, educationally, and culturally. These tendencies toward using sociological characteristics to select a mate has many effects on the lives and livelihoods of those who choose to marry one another, as well as their children and future generations. Within a generation, assortative mating is sometimes cited as a source of inequality, as those who mate assortatively would marry people of similar station to themselves, thus amplifying their current station.<ref name=":0" /> There is debate, however, about whether this growing preference for educational and occupational similarities in spouses is due to increased preferences for these traits or the shift in workload that occurred as women entered the workforce.<ref>{{Cite journal|last1=Breen|first1=Richard|last2=Salazar|first2=Leire|date=2011-01-01|title=Educational Assortative Mating and Earnings Inequality in the United States|jstor=10.1086/661778|journal=American Journal of Sociology|volume=117|issue=3|pages=808–843|doi=10.1086/661778|s2cid=155832686}}</ref> This concentration of wealth in families also perpetuates across generations as parents pass their wealth on to their children, with each successive generation inheriting the resources of both of its parents. The combined resources of the parents allow them to give their child a better life growing up, and the combined inheritances from both parents place them at an even greater advantage than they would be with their superior education and childhoods. This has an enormous impact on the development of the social economic structure of a society.<ref name=":0" /><ref name=":1" />