Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Spread rates of a juvenile-adult population in constant and temporally variable environments.

Abstract

The question of how growth, dispersal, and environmental factors affect the persistence and spread of an invasive species is of great importance in spatial ecology. Motivated by the fact that in a species, different development stages may have different vital rates and dispersal characteristics, we propose and study a reaction-diffusion juvenile-adult model, which is a natural extension of the classical Fisher's equation. We investigate the spread rates of the population if persistent. By comparing our juvenile-adult model with the physically unstructured Fisher model, we find that Fisher equation can be approximated by our juvenile-adult model in several ways. Accordingly, the spreading speed for Fisher's model represents a special case of that for the juvenile-adult model. We analyze how the vital rates and different dispersal abilities between juveniles and adults influence the spreading spread of the structured population, the results indicate that the juvenile-adult model provides more insights into population spread than Fisher equation. We then study a reaction-diffusion juvenile-adult model with temporally periodic coefficients. We develop a novel numerical method to calculate the spreading speed under temporal variability. Finally, we utilize the time-periodic model to understand the spatial spread of a population with separate breeding and non-breeding seasons. In particular, we scrutinize how the seasonal variation in vital rates and dispersal rates, and the duration of the breeding season affect the spreading speed of the population. The theory developed here can provide effective strategies to control the spread of invasive species.