Collaborative Research: Frequency-dependence and its effects on ecological invasions

当一个物种迁入以前没有生态入侵的地区时，就会发生生态入侵。在这种情况下，人口增长，占地面积扩大。如果该物种是一种害虫，其生态和经济代价可能是极端的。物种入侵的一个关键属性是物种在整个景观中传播的速度，入侵速度。现有的数学模型可以根据基本的人口统计信息，如出生率和存活率，以及个人行动来计算入侵速度。然而，大多数模型忽略了男性和女性人口统计和分散率之间的差异。这些性别差异被怀疑限制了真正入侵的成功，但在入侵理论中几乎完全没有被探索过。该项目将开发生物入侵的数学模型，以解释两性之间的相互作用。该理论将能够纳入各种人口统计、人口分布和环境数据。第一步将是分析只区分个人性别的模型。然而，在现实中，雄性和雌性之间的相互作用，如交配和繁殖，通常是特定于年龄的。因此，本研究的第二阶段将分析包括性别和年龄在内的模型。拟议的研究将通过在美国和国外的不同参与者的课程和研讨会上的陈述，以及通过为本科生提供独立的研究经验，来促进教学、培训和学习。将开发的模型将对生态学家和资源管理者广泛有用，并将为保护受威胁物种和控制入侵物种和害虫物种的种群提供信息。将性别差异纳入种群动态的一般模型将扩大我们对物种入侵的理解，并揭示在应用中必须考虑这些因素的情况。

Ecological invasions occur when a species moves into an area where it was previously absent. Following this introduction, the population grows and the area occupied expands. If the species is a pest, the ecological and economic costs can be extreme. A key property of species invasions is the speed with which the species spreads across the landscape, the invasion speed. Mathematical models exist to calculate invasion speeds from basic demographic information, such as birth and survival rates, and from individual movements. Most models, however, ignore differences between male and female demographic and dispersal rates. These gender differences are suspected of limiting the success of real invasions, but are almost completely unexplored in the theory of invasions. This project will develop mathematical models for biological invasions in order to account for the interaction between two sexes. The theory will be capable of incorporating a variety of demographic, dispersal and environmental data. The first step will be to analyze models that distinguish only the sex of individuals. In reality, however, interactions between males and females, such as mating and reproduction, are usually age specific. Therefore the second stage of this research will analyze models that include both sex and age. The proposed research will promote teaching, training, and learning through presentations in courses and workshops for diverse participants, both in the United States and abroad, and by providing independent research experiences for undergraduate students. The models that will be developed will be broadly useful to ecologists and resource managers, and will inform efforts to conserve threatened species and to control populations of invasive and pest species. Incorporating sex differences in general models of population dynamics will expand our understanding of species invasions and reveal the situations in which these factors must be taken into account in applications.