Genetic divergence between two phenotypically distinct bottlenose dolphin ecotypes suggests separate evolutionary trajectories |
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| Authors: | Pedro F Fruet Eduardo R Secchi Juliana C Di Tullio Paulo César Simões‐Lopes Fábio Daura‐Jorge Ana P B Costa Els Vermeulen Paulo A C Flores Rodrigo Cezar Genoves Paula Laporta Luciano B Beheregaray Luciana M Möller |
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| Institution: | 1. Museu Oceanográfico ‘Prof. Eliézer de C. Rios’, Rio Grande, RS, Brazil;2. Laboratório de Ecologia e Conserva??o da Megafauna Marinha – ECOMEGA, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande, RS, Brazil;3. Programa de Pós‐Gradua??o em Oceanografia Biológica, Universidade Federal do Rio Grande (FURG), Rio Grande, RS, Brazil;4. Molecular Ecology Laboratory, Flinders University, Adelaide, SA, Australia;5. Kaosa, Rio Grande, RS, Brazil;6. Laboratório de Mamíferos Aquáticos (LAMAQ), Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brazil;7. Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, USA;8. Whale Unit, Mammal Research Institute, University of Pretoria, Hatfield Pretoria, South Africa;9. Whalefish, Lancefield Quay, Glasgow, UK;10. APA Anhatomirim‐SC, ICMBio, Jurerê, Florianópolis, SC, Brazil;11. Yaqu Pacha Uruguay – Organización para la Conservación de Mamíferos, Punta del Diablo, Rocha, Uruguay;12. Centro Universitario Regional del Este, Universidad de la República, Rocha, Uruguay;13. Cetacean Ecology, Behaviour and Evolution Laboratory, Flinders University, Adelaide, SA, Australia |
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| Abstract: | Due to their worldwide distribution and occupancy of different types of environments, bottlenose dolphins display considerable morphological variation. Despite limited understanding about the taxonomic identity of such forms and connectivity among them at global scale, coastal (or inshore) and offshore (or oceanic) ecotypes have been widely recognized in several ocean regions. In the Southwest Atlantic Ocean (SWA), however, there are scarce records of bottlenose dolphins differing in external morphology according to habitat preferences that resemble the coastal‐offshore pattern observed elsewhere. The main aim of this study was to analyze the genetic variability, and test for population structure between coastal (n = 127) and offshore (n = 45) bottlenose dolphins sampled in the SWA to assess whether their external morphological distinction is consistent with genetic differentiation. We used a combination of mtDNA control region sequences and microsatellite genotypes to infer population structure and levels of genetic diversity. Our results from both molecular marker types were congruent and revealed strong levels of structuring (microsatellites FST = 0.385, p < .001; mtDNA FST = 0.183, p < .001; ΦST = 0.385, p < .001) and much lower genetic diversity in the coastal than the offshore ecotype, supporting patterns found in previous studies elsewhere. Despite the opportunity for gene flow in potential “contact zones”, we found minimal current and historical connectivity between ecotypes, suggesting they are following discrete evolutionary trajectories. Based on our molecular findings, which seem to be consistent with morphological differentiations recently described for bottlenose dolphins in our study area, we recommend recognizing the offshore bottlenose dolphin ecotype as an additional Evolutionarily Significant Unit (ESU) in the SWA. Implications of these results for the conservation of bottlenose dolphins in SWA are also discussed. |
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| Keywords: | biopsy sampling conservation evolutionarily significant unit microsatellites mtDNA South America |
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