Dissecting the null model for biological invasions: A meta-analysis of the propagule pressure effect

• Published in: PLoS biology Vol. 16; no. 4; p. e2005987
• Main Authors: Cassey, Phillip, Delean, Steven, Lockwood, Julie L, Sadowski, Jason S, Blackburn, Tim M
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 23.04.2018; Public Library of Science (PLoS)
• Subjects: Analytical methods; Animal Distribution - physiology; Animals; Bayes Theorem; Bayesian analysis; Biodiversity; Biology and Life Sciences; Ecology; Ecology and Environmental Sciences; Ecosystem; Evolution; Handbooks; Heterogeneity; Introduced Species - statistics & numerical data; Introduced Species - trends; Invertebrates; Invertebrates - physiology; Meta-analysis; Methods; Models, Statistical; Physical Sciences; Plant Dispersal - physiology; Plant introductions; Plants; Poaceae - physiology; Population; Population Dynamics; Population establishment; Pressure; Pressure effects; Research and Analysis Methods; Sample Size; Science Policy; Short Reports; Species Specificity; Success; Survival analysis; Systematic review; Terrestrial environments; Trees - physiology; Vertebrates; Vertebrates - physiology; New York; United Kingdom > UK; United States > US; Adelaide South Australia Australia; California; Australia; New Jersey
• ISSN: 1545-7885; 1544-9173; 1545-7885
• DOI: 10.1371/journal.pbio.2005987

A consistent determinant of the establishment success of alien species appears to be the number of individuals that are introduced to found a population (propagule pressure), yet variation in the form of this relationship has been largely unexplored. Here, we present the first quantitative systematic review of this form, using Bayesian meta-analytical methods. The relationship between propagule pressure and establishment success has been evaluated for a broad range of taxa and life histories, including invertebrates, herbaceous plants and long-lived trees, and terrestrial and aquatic vertebrates. We found a positive mean effect of propagule pressure on establishment success to be a feature of every hypothesis we tested. However, establishment success most critically depended on propagule pressures in the range of 10-100 individuals. Heterogeneity in effect size was associated primarily with different analytical approaches, with some evidence of larger effect sizes in animal rather than plant introductions. Conversely, no variation was accounted for in any analysis by the scale of study (field to global) or methodology (observational, experimental, or proxy) used. Our analyses reveal remarkable consistency in the form of the relationship between propagule pressure and alien population establishment success.