Inbreeding and assortative matingRandom mating with respect to a locus is commonwithin populations, but it is not universal. Two kinds ofdeviation from random mating must be distinguished.First, individuals may mate with others with whom theyshare some degree of common ancestry, that is, some de-gree of genetic relationship. If mating between relativesoccurs more commonly than would occur by purechance, then the population is inbreeding.If mating be-tween relatives is less common than would occur bychance, then the population is said to be undergoing enforced outbreeding,or negative inbreeding.Second, individuals may tend to choose each otheras mates, not because they are related but because oftheir resemblance to each other in some trait. Bias to-ward mating of like with like is called positive assorta-tive mating.Mating with unlike partners is called nega-tive assortative mating.Assortative mating is never com-plete, so that in any population some matings will be atrandom and some the result of assortative mating.Inbreeding and assortative mating are not the same.Close relatives resemble each other more than unrelatedindividuals on the average but not necessarily for anyparticular phenotypic trait in particular individuals. So
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.