Department of Physics, Bar-Ilan University, Ramat-Gan, Israel.
PLoS Comput Biol. 2022 Mar 28;18(3):e1009971. doi: 10.1371/journal.pcbi.1009971. eCollection 2022 Mar.
Temporal environmental variations affect diversity in communities of competing populations. In particular, the covariance between competition and environment is known to facilitate invasions of rare species via the storage effect. Here we present a quantitative study of the effects of temporal variations in two-species and in diverse communities. Four scenarios are compared: environmental variations may be either periodic (seasonal) or stochastic, and the dynamics may support the storage effect (global competition) or not (local competition). In two-species communities, coexistence is quantified via the mean time to absorption, and we show that stochastic variations yield shorter persistence time because they allow for rare sequences of bad years. In diverse communities, where the steady-state reflects a colonization-extinction equilibrium, the actual number of temporal niches is shown to play a crucial role. When this number is large, the same trends hold: storage effect and periodic variations increase both species richness and the evenness of the community. Surprisingly, when the number of temporal niches is small global competition acts to decrease species richness and evenness, as it focuses the competition to specific periods, thus increasing the effective fitness differences.
时间环境变化会影响竞争种群群落的多样性。特别是，竞争与环境之间的协方差被认为通过存储效应促进稀有物种的入侵。在这里，我们对两种和多种群落的时间变化的影响进行了定量研究。比较了四种情况：环境变化可以是周期性（季节性）或随机的，并且动态可以支持存储效应（全球竞争）或不支持存储效应（局部竞争）。在两种群群落中，共存通过吸收的平均时间来量化，我们表明随机变化会导致较短的持续时间，因为它们允许出现罕见的恶劣年份序列。在多样化的群落中，稳定状态反映了一个定居-灭绝的平衡，实际的时间生态位数量被证明起着关键作用。当这个数量很大时，相同的趋势仍然存在：存储效应和周期性变化会增加物种丰富度和群落的均匀度。令人惊讶的是，当时间生态位的数量较小时，全球竞争会降低物种丰富度和均匀度，因为它将竞争集中在特定的时期，从而增加了有效适应度的差异。
