Keil Petr, Clark Adam T, Barták Vojtěch, Leroy François
Faculty of Environmental Sciences Czech University of Life Sciences Prague Praha - Suchdol Czech Republic.
Department of Biology University of Graz Graz Austria.
Ecol Evol. 2025 Mar 27;15(4):e71162. doi: 10.1002/ece3.71162. eCollection 2025 Apr.
Assessment of the rate of species loss, which we also label extinction, is an urgent task. However, the rate depends on spatial grain (average area ) over which it is assessed-local species loss can be, on average, faster or slower than regional or global loss. Ecological mechanisms behind this discrepancy are unclear. We propose that the relationship between extinction rate and is driven by a classical ecological phenomenon: density-dependent mortality. Specifically, we hypothesize that (i) when per-individual probability of death ( ) decreases with the number of individuals in a region (i.e., negative density dependence), per-species extinction rate () should be high at regional grains and low locally. (ii) In contrast, when increases with (i.e., positive density dependence), should be low regionally but high locally. (iii) Total counts of extinct species () should follow a more complex relationship with , as they also depend on drivers of the species-area relationship (SAR) prior to extinctions, such as intraspecific aggregation, species pools, and species-abundance distributions. We tested these hypotheses using simulation experiments, the first based on point patterns and the second on a system of generalized Lotka-Volterra equations. In both experiments, we used a single continuous parameter that moved between the negative, zero, and positive relationship between and . We found support for our hypotheses, but only when regional species-abundance distributions were uneven enough to provide sufficiently rare or common species for density dependence to act on. In all, we have theoretically demonstrated a mechanism behind different rates of biodiversity change at different spatial grains, which has been observed in empirical data.
评估物种丧失速率（我们也将其称为灭绝速率）是一项紧迫的任务。然而，该速率取决于评估时所采用的空间粒度（平均面积）——局部物种丧失速率平均而言可能快于或慢于区域或全球的丧失速率。这种差异背后的生态机制尚不清楚。我们提出，灭绝速率与[此处原文缺失相关内容]之间的关系是由一种经典的生态现象驱动的：密度依赖死亡率。具体而言，我们假设：（i）当区域内个体的死亡概率（[此处原文缺失相关内容]）随着个体数量的增加而降低时（即负密度依赖），区域粒度下的物种灭绝速率（[此处原文缺失相关内容]）应该较高，而局部灭绝速率较低。（ii）相反，当[此处原文缺失相关内容]随着个体数量增加而增加时（即正密度依赖），区域灭绝速率应该较低，但局部灭绝速率较高。（iii）灭绝物种的总数（[此处原文缺失相关内容]）与[此处原文缺失相关内容]之间的关系应该更为复杂，因为它们还取决于灭绝之前物种-面积关系（SAR）的驱动因素，例如种内聚集、物种库和物种丰度分布。我们使用模拟实验对这些假设进行了检验，第一个实验基于点模式，第二个实验基于广义Lotka-Volterra方程系统。在这两个实验中，我们都使用了一个单一的连续参数，该参数在[此处原文缺失相关内容]与[此处原文缺失相关内容]之间的负、零和正关系之间移动。我们的假设得到了支持，但前提是区域物种丰度分布足够不均匀，以便为密度依赖作用提供足够稀有的或常见的物种。总之，我们从理论上证明了在不同空间粒度下生物多样性变化速率不同背后的一种机制，这在实证数据中也有观察到。
