Inbreeding depression in pronghorn (Antilocapra americana) fawns

Although inbreeding depression affects survival, fitness and population viability, the extent of inbreeding depression in wild populations remains unclear. We examined inbreeding depression in the small, isolated National Bison Range (NBR), MT, pronghorn (Antilocapra americana) population following a bottleneck. We have studied the National Bison Range pronghorn extensively since 1981, and we have detailed birth, survival and mate choice data. We genotyped all animals in the population between 1999 and 2010 at 19 microsatellite loci, assigned paternities to all fawns based on genotype and constructed a genetic-based pedigree to calculate inbreeding coefficients (f). We found an increase in the frequency of inbreeding following the bottleneck. We detected evidence of inbreeding depression on fawn survival to weaning, birth mass, foot length and condition. We estimated the number of diploid lethal equivalents on survival to weaning as 24.17-28.72. Standardized heterozygosity (H) had a relatively small influence on survival, mass, length and condition compared with f, and H was not correlated with f. We conclude that for pronghorn, H was not a good predictor of pedigree-estimates of f.