Aquatic Invasions (2016) Volume 11, Issue 1: 101–110 DOI: http://dx.doi.org/10.3391/ai.2016.11.1.11 Open Access © 2016 The Author(s). Journal compilation © 2016 REABIC Research Article Relative importance of propagule size and propagule number for establishment of non-indigenous species: a stochastic simulation study 1,2 3 David Drolet * and Andrea Locke 1Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, C1A 4P3 Canada 2Current address: Fisheries and Oceans Canada, Institut Maurice-Lamontagne, 850 route de la Mer, Mont-Joli, Québec, G5H 3Z4 Canada 3Department of Fisheries and Oceans Canada, Gulf Fisheries Centre, P.O. Box 5030, Moncton, New Brunswick, E1C 9B6 Canada E-mail:
[email protected] (DD),
[email protected] (AL) *Corresponding author Received: 11 February 2015 / Accepted: 23 September 2015 / Published online: 8 December 2015 Handling editor: Charles W. Martin Abstract Propagule pressure is emerging as the most consistent predictor of establishment in non-indigenous species. Increasing propagule size (the number of individuals arriving in a novel environment at one time) is thought to increase probability of establishment by counteracting demographic stochasticity and Allee effects. Increasing propagule number (the number of introduction events) is thought to increase probability of establishment by counteracting environmental stochasticity. However, the relative importance of these effects and the conditions under which one effect may become predominant is largely unexplored. We first used stochastic population simulations, with a constant number of immigrants distributed over varying numbers of introduction events, to determine the relative importance of propagule size and number on the probability of establishment.