Pedigree Analysis for Population Management

Abstract

The long-term survival of a population depends on the maintenance of sufficient genetic variation for individual fitness and population adapt ability. Inbreeding depression, the reduction of fecundity and viability in progeny of matings between close genetic relatives, has been extensively documented in domesticated livestock (Darwin 1868; Wright 1977; Falconer 1981), captive populations of wild animals (Ralls et a!. 1988; Lacy et al. 1993), and in many, but not all, wild populations (Wildt et a!. 1987; Thornhill 1993 ). The loss of individual heterozygosity that occurs with inbreeding results in the expression of deleterious recessive genes and the loss of heterotic effects at overdominant loci (both components of the "genetic load" of a normally outbreeding population). Even if an inbred population is viable in its present environment, a lack of allelic diversity due to fixation of alleles by genetic drift would preclude an adaptive response to natural selection when the environment changes (Robertson 1960; Selander 1983; Allendorf 1986).