Negative density-dependent dispersal in the American black bear (Ursus americanus) revealed by noninvasive sampling and genotyping

Abstract

Although the dispersal of animals is influenced by a variety of factors, few studies have used a condition-dependent approach to assess it. The mechanisms underlying dispersal are thus poorly known in many species, especially in large mammals. We used 10 microsatellite loci to examine population density effects on sex-specific dispersal behavior in the American black bear, Ursus americanus.We testedwhether dispersal increases with population density in both sexes. Fine-scale genetic structure was investigated in each of four sampling areas usingMantel tests and spatial autocorrelation analyses. Our results revealed male-biased dispersal pattern in lowdensity areas. As population density increased, females appeared to exhibit philopatry at smaller scales. Fine-scale genetic structure for males at higher densities may indicate reduced dispersal distances and delayed dispersal by subadults. © 2012 The Authors. Ecology and Evolution published by Blackwell Publishing Ltd.