Positively and Negatively Autocorrelated Environmental Fluctuations Have Opposing Effects on Species Coexistence
Positively and Negatively Autocorrelated Environmental Fluctuations Have Opposing Effects on Species Coexistence
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正自相关和负自相关的环境波动对物种共存具有相反的影响
DOI：
10.1086/713066
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Schreiber, Sebastian J.
中科院分区：
文献类型：
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作者：
Schreiber, Sebastian J.
环境波动可以通过储存效应调节相互竞争的物种之间的共存。这种依赖波动的共存机制需要三个条件：(I)物种对环境条件的反应与竞争强度之间存在正协方差，(Ii)存在物种特有的环境反应，(Iii)物种在环境不利的年份对竞争不那么敏感。在序列不相关的环境中，条件(I)只有在有利的环境条件立即和直接增加竞争实力的情况下才会发生。对于许多人口统计参数来说，有利年份和竞争之间的这种直接联系可能并不存在。此外，许多环境变量是时间自相关的，但理论主要集中在序列不相关的环境上。为了解决这一差距，分析了自相关环境中竞争物种的模型。这一分析表明，增加适合度(例如，最大繁殖力或成虫存活率)的人口率的正自相关性在条件(I)中产生正的环境-竞争协方差。因此，当这些人口比率有助于缓冲人口增长时，正的时间自相关会产生存储效应；否则，它们会破坏竞争互动的稳定性。对于负自相关环境，该理论强调了一种替代的稳定机制，该机制需要三个条件：(i‘)存在负的环境-竞争协方差，(Ii)存在特定物种的环境反应，以及(iii’)物种在较有利的年份对竞争不那么敏感。当这两种稳定机制中的任何一种的条件被违反时，时间自相关可能会产生随机优先效应或加速竞争排斥。总而言之，这些结果突显了环境条件的时间自相关性在决定竞争物种的生态结果方面发挥着基础性作用。
Environmental fluctuations can mediate coexistence between competing species via the storage effect. This fluctuation-dependent coexistence mechanism requires three conditions: (i) there is a positive covariance between species responses to environmental conditions and the strength of competition, (ii) there are species-specific environmental responses, and (iii) species are less sensitive to competition in environmentally unfavorable years. In serially uncorrelated environments, condition (i) occurs only if favorable environmental conditions immediately and directly increase the strength of competition. For many demographic parameters, this direct link between favorable years and competition may not exist. Moreover, many environmental variables are temporal autocorrelated, but theory has largely focused on serially uncorrelated environments. To address this gap, a model of competing species in autocorrelated environments is analyzed. This analysis shows that positive autocorrelations in demographic rates that increase fitness (e.g., maximal fecundity or adult survival) produce the positive environment-competition covariance in condition (i). Hence, when these demographic rates contribute to buffered population growth, positive temporal autocorrelations generate a storage effect; otherwise, they destabilize competitive interactions. For negatively autocorrelated environments, this theory highlights an alternative stabilizing mechanism that requires three conditions: (i′) there is a negative environment-competition covariance, (ii) there are species-specific environmental responses, and (iii′) species are less sensitive to competition in more favorable years. When the conditions for either of these stabilizing mechanisms are violated, temporal autocorrelations can generate stochastic priority effects or hasten competitive exclusion. Collectively, these results highlight that temporal autocorrelations in environmental conditions can play a fundamental role in determining ecological outcomes of competing species.