Introduction
The mating of related individuals is known as inbreeding. Inbreeding can be defined by Wright’s coefficient which calculates the probability of identity-by-descent of two alleles at a locus in an individual (Charlesworth & Charlesworth, 1987). A high level of inbreeding in a population can have a detrimental effect, this is known as inbreeding depression and is defined as a decline in fitness caused by increased homozygosity of offspring (Brakefield et. al, 1996). It can be detected by a decrease in growth rates, fertility, and survival in individuals with a high inbreeding coefficient (Charlesworth & Willis, 2009). Inbreeding is more common in small, isolated populations, due to a lack of breeding partners (Lande & Schemske, 1985). The most extreme form of inbreeding is selfing, the act of an individual mating with itself (Lande & Schemske, 1985).
In a highly inbred population, ‘purging’ may occur which removes deleterious, recessive mutations from the population, thereby decreasing the effects of inbreeding depression (Byers & Waller, 1999). Purging takes place due to the strong selection against deleterious…show more content… It is known as ‘purging the genetic load’, and takes place in highly inbred populations (Barret & Crnokink 2002). The genetic load refers to the accumulation of lethal or deleterious alleles that cause inbreeding depression when increased in frequency (Brakefield et. al, 1996). Purging takes place as there is strong selection against deleterious homozygotes and natural selection is more effective where inbreeding is present (Willis, 1999). This is because when there is a large amount of deleterious alleles present in a population, the genetic load becomes more visible to natural selection and can then be removed over a small number of generations. In a 2003 study, Glemin suggested that there were two processes of purging. These are summarised in table
