Accumulation of deleterious mutations and equalization of parental contributions in the conservation of genetic resources.

Typical management strategies for the conservation of endangered species in captivity, such as equalization of family sizes, deal with the need for maintaining genetic variability and low levels of inbreeding, and for preventing the population from adapting to captivity. But they also produce a reduction in the intensity of natural selection, so that deleterious mutations can accumulate more easily in small populations. We have carried out computer simulations to investigate the effect of equalizing contributions on the accumulation of deleterious mutations. The models include effects on fecundity and viability, and account for different sets of mutational parameters and reproductive rates. The effect of relaxation of selection under captive conditions was also investigated. Our results suggest that equalization of family sizes does not produce a particularly high threat to small conserved populations, at least in the short term (up to about 20 generations), and the more efficient preservation of genetic variability seems to be a clear advantage of the procedure.