The efficiency of close inbreeding to reduce genetic adaptation to captivity

Abstract

Although ex situ conservation is indispensable for thousands of species, captive breeding is associated with negative genetic changes: loss of genetic variance and genetic adaptation to captivity that is deleterious in the wild. We used quantitative genetic individual-based simulations to model the effect of genetic management on the evolution of a quantitative trait and the associated fitness of wild-born individuals that are brought to captivity. We also examined the feasibility of the breeding strategies under a scenario of a large number of loci subject to deleterious mutations. We compared two breeding strategies: repeated half-sib mating and a method of minimizing mean coancestry (referred to as gc/mc). Our major finding was that halfsib mating is more effective in reducing genetic adaptation to captivity than the gc/mc method. Moreover, half-sib mating retains larger allelic and adaptive genetic variance. Relative to initial standing variation, the additive variance of the quantitative trait increased under half-sib mating during the sojourn in captivity. Although fragmentation into smaller populations improves the efficiency of the gc/mc method, half-sib mating still performs better in the scenarios tested. Half-sib mating shows two caveats that could mitigate its beneficial effects: low heterozygosity and high risk of extinction when populations are of low fecundity and size and one of the following conditions are met: (i) the strength of selection in captivity is comparable with that in the wild, (ii) deleterious mutations are numerous and only slightly deleterious. Experimental validation of half-sib mating is therefore needed for the advancement of captive breeding programs.

Conservation biology of the last Italian population of Cistus laurifolius (Cistaceae): demographic structure, reproductive success and population genetics

“…Despite habitat fragmentation seeming to have no effect on the reproductive fitness, it is argued that this species in Italy could be affected by an ongoing process of population size reduction, linked to inbreeding depression, loss of genetic variation and fixation of deleterious alleles. All these factors play a role in reducing the adaptive potential of a population (Del-mas et al 2014;Theodorou and Couvet 2015). This local reduction and impoverishment is congruent with a general range contraction and fragmentation, already highlighted in this species by Fernández-Mazuecos and Vargas (2010).…”

Genetic and demographic vulnerability of adder populations: Results of a genetic study in mainland Britain

“…We have nevertheless exposed a previously undocumented degree of consanguinity in wild adder populations, despite their showing no increase in homozygosity to suggest inbreeding depression. In models of inbreeding, a system of half-sib mating is more likely to maintain heterozygosity than one of maximum avoidance of inbreeding [84,85]. Polyandry, which is widespread in taxa of live-bearing snakes [86], including the adder [87][88][89], may thus represent a protective mechanism against inbreeding [82,90].…”

Inbreeding depression and drift load in small populations at demographic disequilibrium

“…; García‐Dorado 2003; Jaquiery et al. ; Theodorou and Couvet ). We considered a two allele per locus model, A being the wild‐type allele and a , a deleterious and partially recessive allele.…”