Role of Propagule Pressure in Biological Invasions

• Published in: Annual review of ecology, evolution, and systematics Vol. 40; no. 1; pp. 81 - 102
• Main Author: Simberloff, Daniel
• Format: Journal Article
• Language: English
• Published: Palo Alto, CA Annual Reviews 01-12-2009; Annual Reviews, Inc
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biological invasions; Demography; Ecological invasion; Ecosystems; Environmental impact; Fundamental and applied biological sciences. Psychology; General aspects; Genetic diversity; Genetic variation; Genetics; Habitats; Indigenous species; introduced plants; Introduced species; Invasions; Invasive species; literature reviews; Nonnative species; plant ecology; plant establishment; plant reproduction; Population genetics; Population growth; Population size; propagule arrival; propagule number; propagule pressure; propagule size; Species; Stochastic models; Genetic drift; Inbreeding depression; Biological invasion; Demography; Seeds; SCOPE; environmental stochasticity; Propagule; Review; lag; invasion; demographic stochasticity; Ecological niche; Environment; Models; niche models
• ISSN: 1543-592X; 1545-2069
• DOI: 10.1146/annurev.ecolsys.110308.120304

Although most studies of factors contributing to successful establishment and spread of non-native species have focused on species traits and characteristics (both biotic and abiotic), increasing empirical and statistical evidence implicates propagule pressure—propagule sizes, propagule numbers, and temporal and spatial patterns of propagule arrival—as important in both facets of invasion. Increasing propagule size enhances establishment probability primarily by lessening effects of demographic stochasticity, whereas propagule number acts primarily by diminishing impacts of environmental stochasticity. A continuing rain of propagules, particularly from a variety of sources, may erase or vitiate the expected genetic bottleneck for invasions initiated by few individuals (as most are), thereby enhancing likelihood of survival. For a few species, recent molecular evidence suggests ongoing propagule pressure aids an invasion to spread by introducing genetic variation adaptive for new areas and habitats. This phenomenon may also explain some time lags between establishment of a non-native species and its spread to become an invasive pest.