Condition-dependent movement and dispersal in experimental metacommunities

Dispersal and the underlying movement behaviour are processes of pivotal importance for understanding and predicting metapopulation and metacommunity dynamics. Generally, dispersal decisions are condition-dependent and rely on information in the broad sense, like the presence of conspecifics. However, studies on metacommunities that include interspecific interactions generally disregard condition-dependence. Therefore, it remains unclear whether and how dispersal in metacommunities is condition-dependent and whether rules derived from single-species contexts can be scaled up to (meta)communities. Using experimental protist metacommunities, we show how dispersal and movement depend on and are adjusted by the strength of interspecific interactions. We found that the predicting movement and dispersal in metacommunities requires knowledge on behavioural responses to intra- and interspecific interaction strengths. Consequently, metacommunity dynamics inferred directly from single-species metapopulations without taking interspecific interactions into account are likely flawed. Our work identifies the significance of condition-dependence for understanding metacommunity dynamics, stability and the coexistence and distribution of species.

扩散及其背后的运动行为，是理解与预测集合种群（metapopulation）和集合群落（metacommunity）动态的核心关键过程。通常而言，扩散决策依赖于环境条件，且会利用广义层面的各类信息，例如同种个体的存在情况。然而，现有涉及种间相互作用的集合群落研究，大多忽略了这种条件依赖性。因此，目前仍不清楚集合群落中的扩散是否具备条件依赖性、其依赖方式如何，以及从单物种种群情境中推导得出的扩散规则，能否推广至（集合）群落层面。本研究借助实验原生生物（protist）集合群落，揭示了扩散与运动行为如何依赖种间相互作用强度，并随其发生调整。我们发现，若要预测集合群落中的运动与扩散过程，必须掌握生物对种内与种间相互作用强度的行为响应规律。因此，若直接基于单物种种群集合体推导集合群落动态，而未考虑种间相互作用，所得结论大概率存在缺陷。本研究明确了条件依赖性对于理解集合群落动态、稳定性以及物种共存与分布的重要意义。