Characterizing dispersal patterns in a threatened seabird with limited genetic structure |
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| Authors: | LAURIE A. HALL PER J. PALSBØLL STEVEN R. BEISSINGER JAMES T. HARVEY MARTINE BÉRUBÉ MARTIN G. RAPHAEL S. KIM NELSON RICHARD T. GOLIGHTLY LAURA MCFARLANE‐TRANQUILLA SCOTT H. NEWMAN M. ZACHARIAH PEERY |
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| Affiliation: | 1. Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA;2. Department of Genetics, Microbiology and Toxicology, Stockholm University, 106 91, Stockholm, Sweden;3. Department of Environmental Science, Policy and Management, University of California, Berkeley, 137 Mulford Hall, Berkeley, CA 94720‐3114, USA;4. Wildlife Ecology, USDA Forest Service, Pacific Northwest Research Station, 3625 93rd Avenue SW, Olympia, WA 98512,USA;5. Oregon State University, Oregon Cooperative Fish and Research Unit, Department of Fisheries and Wildlife, 104 Nash Hall, Corvallis, OR 97331, USA;6. Department of Wildlife, Humboldt State University, 1 Harpst Street, Arcata, CA 95521, USA;7. Centre for Wildlife Ecology, Simon Fraser University, 8888 University Avenue, Burnaby, BC, V5A 1S6, Canada;8. Food and Agricultural Organization of the United Nations, EMPRES Wildlife Unit, Infectious Disease Group, Via Terme di Caracalla, Rome 00153, Italy;9. Department of Forest and Wildlife Ecology, 1630 Russell Labs, University of Wisconsin‐Madison, Madison, WI 53706, USA |
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| Abstract: | Genetic assignment methods provide an appealing approach for characterizing dispersal patterns on ecological time scales, but require sufficient genetic differentiation to accurately identify migrants and a large enough sample size of migrants to, for example, compare dispersal between sexes or age classes. We demonstrate that assignment methods can be rigorously used to characterize dispersal patterns in a marbled murrelet (Brachyramphus marmoratus) population from central California that numbers approximately 600 individuals and is only moderately differentiated (FST～ 0.03) from larger populations to the north. We used coalescent simulations to select a significance level that resulted in a low and approximately equal expected number of type I and II errors and then used this significance level to identify a population of origin for 589 individuals genotyped at 13 microsatellite loci. The proportion of migrants in central California was greatest during winter when 83% of individuals were classified as migrants compared to lower proportions during the breeding (6%) and post‐breeding (8%) seasons. Dispersal was also biased toward young and female individuals, as is typical in birds. Migrants were rarely members of parent‐offspring pairs, suggesting that they contributed few young to the central California population. A greater number of migrants than expected under equilibrium conditions, a lack of individuals with mixed ancestry, and a small number of potential source populations (two), likely allowed us to use assignment methods to rigorously characterize dispersal patterns for a population that was larger and less differentiated than typically thought required for the identification of migrants. |
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| Keywords: | age‐biased dispersal assignment methods Brachyramphus marmoratus marbled murrelet microsatellites migrants sex‐biased dispersal |
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