PDF(Pubmed)
Abstract：
Although it is well established that density dependence drives changes in organismal abundance over time, relatively little is known about how density dependence affects variation in abundance over space. We tested the hypothesis that spatial trade-offs between food and safety can change the drivers of population distribution, caused by opposing patterns of density-dependent habitat selection (DDHS) that are predicted by the multidimensional ideal free distribution. We addressed this using winter aerial survey data of northern Yellowstone elk (Cervus canadensis) spanning four decades. Supporting our hypothesis, we found positive DDHS for food (herbaceous biomass) and negative DDHS for safety (openness and roughness), such that the primary driver of habitat selection switched from food to safety as elk density decreased from 9.3 to 2.0 elk/km2 . Our results demonstrate how population density can drive landscape-level shifts in population distribution, confounding habitat selection inference and prediction and potentially affecting community-level interactions.
摘要：
尽管众所周知，密度依赖性会随着时间的推移驱动生物体丰度的变化，关于密度依赖性如何影响空间丰度变化的知识相对较少。我们检验了这样一个假设，即食品和安全之间的空间权衡可以改变人口分布的驱动因素，由多维理想自由分布预测的密度依赖性栖息地选择（DDHS）的相反模式引起。我们使用了长达40年的北黄石麋鹿（Cervuscanadensis）的冬季航空调查数据来解决此问题。支持我们的假设,我们发现食物（草本生物量）为正DDHS，安全性为负DDHS（开放性和粗糙度），这样，随着麋鹿密度从9.3下降到2.0麋鹿/km2，栖息地选择的主要驱动因素从食物转向安全。我们的结果表明人口密度如何驱动人口分布的景观水平变化，混杂的栖息地选择推断和预测，并可能影响社区层面的互动。
