Stage-mediated priority effects and season lengths shape long-term competition dynamics

The relative arrival time of species can affect their interactions and
thus determine which species persist in a community. Although this
phenomenon, called priority effect, is widespread in natural communities,
it is unclear how it depends on the length of growing season. Using a
seasonal stage-structured model, we show that differences in stages of
interacting species could generate priority effects by altering the
strength of stabilizing and equalizing coexistence mechanisms, changing
outcomes between exclusion, coexistence, and positive frequency
dependence. However, these priority effects are strongest in systems with
just one or a few generations per season and diminish in systems where
many overlapping generations per season dilute the importance of
stage-specific interactions. Our model reveals a novel link between the
number of generations in a season and the consequences of priority
effects, suggesting that consequences of phenological shifts driven by
climate change should depend on specific life histories of organisms.

物种的相对到达时间可影响其种间相互作用，进而决定群落中哪些物种能够存续。尽管这一被称为优先效应（priority effect）的现象在自然群落中广泛存在，但目前尚不清楚其如何随生长季长度发生变化。本研究借助季节性阶段结构模型，证实互作物种的发育阶段差异可通过改变稳定共存与均等共存机制的强度，改变物种排除、共存以及正频率依赖等不同结局，从而产生优先效应。然而，这类优先效应在每个生长季仅存在1代或少数几代的系统中最为显著，而在每个生长季存在多代重叠个体、阶段特异性相互作用的重要性被稀释的系统中，其效应会有所减弱。我们的模型揭示了生长季内世代数与优先效应后果之间的全新关联，这表明气候变化驱动的物候转变所带来的影响，应取决于物种特有的生活史特征。