A recent article by Willoughby et al., (2014) addresses the impact of genetic diversity loss amongst species in captive breeding programmes and analyses three different breeding methods and their outcomes.
Genetic diversity helps to maintain the health of a species by including valuable alleles (heritable traits) to resist against things like disease, pests, and environmental change. A population that has a higher variability of alleles will be better able to evolve and survive these challenges. In captive breeding, maintenance of this diversity is critical to the success of re-introduction programs especially in endangered species whose population size tends to be small.
Populations of white-footed mice (Peromyscus leucopus; Rafineque 1818) were used to compare the genetic diversity patterns between three breeding protocols – random mating (RAN), minimising mean kinship (MK) being the probability that one allele sampled in an individual is identical by descent with an allele found in another random sample from the same population and docility selection (DOC) where more behaviourally sedentary individuals are paired with each other to imitate the selection for docility that can occur in captivity.
In each protocol, the variation of alleles was measured along with the heterozygosity which determines the number of genes with two different alleles. Low heterozygosity would indicate minimal genetic variability as high heterozygosity indicates higher variability making it a popular measurement of genetic variation in natural populations.
All populations in the study were successfully bred using these protocols although the DOC population expired after generation 9 (of 20 in the study) due to reproductive failure which indicates that fitness was severely reduced due to inbreeding depression (Willoughby et al. (2014). Inbreeding rates increased in all populations throughout the study but the researchers determined that genetic diversity was consistently observed in minimised MK breeding more effectively than random mating (RAN) or docility selection (DOC).
Willoughby et al., (2014) therefore suggest that the MK protocol be the preferred method of breeding protocol when maintaining genetic diversity in captive populations.
J. Willoughby, N. Fernandez, M. Lamb, J. Ivy, R. Lacy and J. Dewoody, (2014) The impacts of inbreeding, drift and selection on genetic diversity in captive breeding populations. Molecular Ecology 24: 98-110