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

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

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.