Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.
Proc Biol Sci. 2024 Oct;291(2032):20241221. doi: 10.1098/rspb.2024.1221. Epub 2024 Oct 9.
Season length and its associated variables can influence the expression of social behaviours, including the occurrence of eusociality in insects. Eusociality can vary widely across environmental gradients, both within and between different species. Numerous theoretical models have been developed to examine the life history traits that underlie the emergence and maintenance of eusociality, yet the impact of seasonality on this process is largely uncharacterized. Here, we present a theoretical model that incorporates season length and offspring development time into a single, individual-focused model to examine how these factors can shape the costs and benefits of social living. We find that longer season lengths and faster brood development times are sufficient to favour the emergence and maintenance of a social strategy, while shorter seasons favour a solitary one. We also identify a range of season lengths where social and solitary strategies can coexist. Moreover, our theoretical predictions are well matched to the natural history and behaviour of two flexibly eusocial bee species, suggesting that our model can make realistic predictions about the evolution of different social strategies. Broadly, this work reveals the crucial role that environmental conditions can have in shaping social behaviour and its evolution and it underscores the need for further models that explicitly incorporate such variation to study the evolutionary trajectories of eusociality.
季节长度及其相关变量会影响社会行为的表达，包括昆虫的真社会性的出现。真社会性在不同物种之间和内部的环境梯度上差异很大。已经开发了许多理论模型来研究真社会性出现和维持的基础的生活史特征，但季节变化对这一过程的影响在很大程度上还没有被描述。在这里，我们提出了一个理论模型，将季节长度和后代发育时间纳入一个单一的、以个体为中心的模型中，以研究这些因素如何塑造社会生活的成本和收益。我们发现，较长的季节长度和较快的幼虫发育时间足以促进社会策略的出现和维持，而较短的季节则有利于独居策略。我们还确定了一系列可以共存的季节长度，其中社会和独居策略可以共存。此外，我们的理论预测与两种灵活的社会性蜜蜂物种的自然历史和行为非常吻合，这表明我们的模型可以对不同社会策略的进化做出现实的预测。总的来说，这项工作揭示了环境条件在塑造社会行为及其进化方面的关键作用，并强调需要进一步的模型来明确纳入这种变化，以研究真社会性的进化轨迹。
