Sex differences and allee effects shape the dynamics of sex-structured invasions

The rate at which a population grows and spreads can depend on individual behaviour and interactions with others. In many species with two sexes, males and females differ in key life history traits (e.g. growth, survival, dispersal), which can scale up to affect population rates of growth and spread. In sexually reproducing species, the mechanics of locating mates and reproducing successfully introduce further complications for predicting the invasion speed (spread rate), as both can change nonlinearly with density. Most models of population spread are based on one sex, or include limited aspects of sex differences. Here we ask whether and how the dynamics of finding mates interact with sex-specific life history traits to influence the rate of population spread. We present a hybrid approach for modelling invasions of populations with two sexes that links individual-level mating behaviour (in an individual-based model) to population-level dynamics (in an integrodifference equation mode...种群增长与扩散的速率，取决于个体行为及其与其他个体的互动。在许多具有两性的物种中，雄性与雌性在关键生活史特征（life history traits）——例如生长、存活、扩散——上存在差异，这类差异可放大影响种群的增长与扩散速率。对于有性繁殖物种而言，寻找配偶与成功繁殖的机制会为入侵速率（扩散速率）的预测带来更多复杂因素，因为这两个过程均会随种群密度发生非线性变化。 多数种群扩散模型仅基于单一性别构建，或是仅涉及性别差异的有限方面。本研究旨在探讨：寻找配偶的动态过程是否以及如何与性别特异性生活史特征相互作用，进而影响种群扩散速率。 我们提出一种用于构建两性种群入侵模型的混合方法，该方法将个体层面的交配行为（基于个体的模型（individual-based model））与种群层面的动态（积分差分方程（integrodifference equation）模型）相结合……