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Short-range dispersal maintains a volatile marine metapopulation: the brown alga Postelsia palmaeformis

Author(s): Paine, Robert T.; Buhle, Eric R.; Levin, Simon A.; Kareiva, Peter

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Abstract: The annual brown alga Postelsia palmaeformis is dependent for its survival on short-distance dispersal (SDD) where it is already established, as well as occasional long-distance colonization of novel sites. To quantify SDD, we transplanted Postelsia to sites lacking established plants within ≥10 m. The spatial distribution of the first naturally produced sporophyte generation was used to fit dispersal kernels in a hierarchical Bayesian framework. Mean dispersal distance within a year ranged from 0.16 to 0.50 m across sites; 95% of the recruits were within 0.38 to 1.32 m of the transplant. The fat-tailed exponential square root kernel was the best among the candidate models at describing offspring density and dispersal. Independent measurements of patch size over 2-5 generations permitted an evaluation of whether models parameterized by individual-level data could adequately predict longer-term persistence and spread at the patch scale. The observed spread rates generally fell within the 95% predictive intervals. Finally, Postelsia was eliminated from 14 occupied sites that were then followed for ≥27 years. The probability of invasion when unoccupied declined and the probability of extinction when occupied increased with distance from the nearest propagule source. Sites >10 m from a source were rarely invaded, and one initially densely populated site isolated by 39 m has remained Postelsia-free since 1981. In spite of dispersal that is almost entirely within 2 m of the parent, the ability of our models to capture the observed dynamics of Postelsia indicates that short-range dispersal adequately explains the persistent and thriving Postelsia metapopulation on Tatoosh Island. However, the presence of Postelsia over a 2000-km coastal range with many gaps >1 km makes it clear that rare long-distance dispersal must be required to explain the geographic range of the species.
Publication Date: Jun-2017
Electronic Publication Date: 2-May-2017
Citation: Paine, Robert T., Buhle, Eric R., Levin, Simon A., Kareiva, Peter. (2017). Short-range dispersal maintains a volatile marine metapopulation: the brown alga Postelsia palmaeformis. Ecology, 98 (6), 1560 - 1573. doi:10.1002/ecy.1798
DOI: doi:10.1002/ecy.1798
ISSN: 0012-9658
Pages: 1560 - 1573
Type of Material: Journal Article
Journal/Proceeding Title: Ecology
Version: Author's manuscript

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