Intrinsic and extrinsic sources of variation in the dynamics of large herbivore populations

摘要: We evaluated the relative importance of intrinsic (density-dependent) and extrinsic (density-independent) sour- ces resource variability in dynamics bighorn sheep (Ovis canadensis Shaw, 1804) populations southwestern USA. tested hypothesis that experiencing greater variation forage availability are less likely to be at equilibrium density with supplies, thus, would demonstrate weaker evidence intraspecific competition. used regression relate population growth rate rainfall (forage conditions) abundance (intraspecific competition) for 20 populations, we estimated strength effects each population. Then compared among look relationships between strengths variabil- ity experienced by Populations demonstrating a effect were associated environ- ments having lower than those did not. showing environments higher lacked effect. These findings consistent hy- pothesis resources achieve an supplies where competition large determinant