Inbreeding depression and genetic load in laboratory metapopulations of the butterfly Bicyclus anynana

We investigated the effects of inbreeding on various fitness components and their genetic load in laboratory metapopulations of the butterfly Bicyclus anynana. Six metapopulations each consisted of four subpopulations with br eeding population sizes of N = 6 or N = 12 and migration rate of m = 0 or n l = 0.33. Metapopulations were maintained for seven generations during whic h coancestries and pedigrees were established. Individual inbreeding coeffi cients at the F-7 were calculated and ranged between 0.01 and 0.51. Even th ough considerable purging had occurred during inbreeding, the genetic load remained higher than that of many outbreeding species: approximately two le thal equivalents were detected for egg sterility, one for zygote survival, one for juvenile survival, and one for longevity. Severe inbreeding depress ion occurred after seven generations of inbreeding, which jeopardized the m etapopulation survival. This finding suggests that the purging of genetic l oad by intentional inbreeding cannot be recommended for the genetic conserv ation of species with a high number of lethal equivalents.