Multiple processes drive genetic structure of humpback whale (Megaptera novaeangliae) populations across spatial scales |
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Authors: | Francine Kershaw Inês Carvalho Jacqueline Loo Cristina Pomilla Peter B Best Ken P Findlay Salvatore Cerchio Tim Collins Marcia H Engel Gianna Minton Peter Ersts Jaco Barendse P G H Kotze Yvette Razafindrakoto Solange Ngouessono Michael Meÿer Meredith Thornton Howard C Rosenbaum |
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Institution: | 1. Columbia University, New York, NY, USA;2. Population and Conservation Genetics Group, Instituto Gulbenkian de Ciência, Oeiras, Portugal;3. Centre for Environmental and Marine Studies (CESAM), Universidade de Aveiro, Aveiro, Portugal;4. Department of Biology, New York University, New York, NY, USA;5. Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK;6. Mammal Research Institute, University of Pretoria, Cape Town, South Africa;7. Wildlife Conservation Society, Ocean Giants Program, Bronx, NY, USA;8. Environment Society of Oman, Ruwi, Sultanate of Oman;9. Humpback Whale Project/Humpback Whale Institute, Caravelas, Bahia, Brazil;10. Center for Biodiversity and Conservation, American Museum of Natural History, New York, NY, USA;11. Department of Environmental Affairs, Branch Oceans and Coasts, Cape Town, South Africa;12. Wildlife Conservation Society‐Madagascar Program, Bronx, NY, USA;13. Agence Nationale des Parcs Nationaux, Libreville, Gabon;14. Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, NY, USA |
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Abstract: | Elucidating patterns of population structure for species with complex life histories, and disentangling the processes driving such patterns, remains a significant analytical challenge. Humpback whale (Megaptera novaeangliae) populations display complex genetic structures that have not been fully resolved at all spatial scales. We generated a data set of nuclear markers for 3575 samples spanning the seven breeding stocks and substocks found in the South Atlantic and western and northern Indian Oceans. For the total sample, and males and females separately, we assessed genetic diversity, tested for genetic differentiation between putative populations and isolation by distance, estimated the number of genetic clusters without a priori population information and estimated rates of gene flow using maximum‐likelihood and Bayesian approaches. At the ocean basin scale, structure is governed by geographical distance (IBD P < 0.05) and female fidelity to breeding areas, in line with current understanding of the drivers of broadscale population structure. Consistent with previous studies, the Arabian Sea breeding stock was highly genetically differentiated (FST 0.034–0.161; P < 0.01 for all comparisons). However, the breeding stock boundary between west South Africa and east Africa was more porous than expected based on genetic differentiation, cluster and geneflow analyses. Instances of male fidelity to breeding areas and relatively high rates of dispersal for females were also observed between the three substocks in the western Indian Ocean. The relationships between demographic units and current management boundaries may have ramifications for assessments of the status and continued protections of populations still in recovery from commercial whaling. |
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Keywords: | behaviour humpback whale International Whaling Commission population genetics Southern Hemisphere wildlife management |
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