genetic purging
Bouzat JL 2010 Conservation genetics of population bottlenecks: the role of chance, selection, and history. Conserv Genet 11:463-478.
- it has been commonly accepted that purging is a very unlikely process in small populations
- purging using rapid inbreeding in very small populations cannot be relied upon to eliminate the deleterious effects of inbreeding
- most of the evidence collected so far suggests that the purging process does not play a substantial role in the majority of populations
- until recently there have been no studies providing direct evidence on the role of selective purging in small populations, particularly from animal species
- purging may be an effective force in reducing the magnitude of inbreeding depression that a population may experience following a bottleneck
- significant reductions in inbreeding depression can be explained, therefore, as a result of natural selection eliminating deleterious recessive alleles by purging the genetic load of populations subjected to high levels of inbreeding
- the hypothesis that purging may decrease extinction probabilities is much more difficult to test
- to date there has been few studies on this particular question
- in some occasions, populations that have undergone drastic reductions in population size retained relatively high reproductive rates and recovered rapidly with minimal management intervention
- regarding the inbreeding environment, one would expect that recessive alleles may become more deleterious under stressful conditions
- recessive deleterious alleles may, therefore, be more readily eliminated through natural selection decreasing the genetic load of populations reducing inbreeding depression
- the efficiency of purging in decreasing inbreeding depression may also be highly variable
