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Fruet P.F.,Programa de Pos Graduacao em Oceanografia Biologica | Fruet P.F.,Flinders University | Fruet P.F.,Institute Oceanografia | Secchi E.R.,Museu Oceanografico Prof. Eliezer C. Rios | And 15 more authors.
Conservation Genetics | Year: 2014

Knowledge about the ecology of bottlenose dolphins in the Southwestern Atlantic Ocean is scarce. Increased by-catch rates over the last decade in coastal waters of southern Brazil have raised concerns about the decline in abundance of local dolphin communities. Lack of relevant data, including information on population structure and connectivity, have hampered an assessment of the conservation status of bottlenose dolphin communities in this region. Here we combined analyses of 16 microsatellite loci and mitochondrial DNA (mtDNA) control region sequences to investigate genetic diversity, structure and connectivity in 124 biopsy samples collected over six communities of photographically identified coastal bottlenose dolphins in southern Brazil, Uruguay and central Argentina. Levels of nuclear genetic diversity were remarkably low (mean values of allelic diversity and heterozygosity across all loci were 3.6 and 0.21, respectively), a result that possibly reflects the small size of local dolphin communities. On a broad geographical scale, strong and significant genetic differentiation was found between bottlenose dolphins from southern Brazil-Uruguay (SB-U) and Bahía San Antonio (BSA), Argentina (AMOVA mtDNA ΦST = 0.43; nuclear FST = 0.46), with negligible contemporary gene flow detected based on Bayesian estimates. On a finer scale, moderate but significant differentiation (AMOVA mtDNA ΦST = 0.29; nuclear FST = 0.13) and asymmetric gene flow was detected between five neighbouring communities in SB-U. Based on the results we propose that BSA and SB-U represent two distinct evolutionarily significant units, and that communities from SB-U comprise five distinct Management Units (MUs). Under this scenario, conservation efforts should prioritize the areas in southern Brazil where dolphins from three MUs overlap in their home ranges and where by-catch rates are reportedly higher. © 2014 Springer Science+Business Media Dordrecht.

Fruet P.F.,Federal University of Rio Grande do Sul | Fruet P.F.,Institute Oceanografia | Fruet P.F.,Flinders University | Genoves R.C.,Museu Oceanografico Prof. Eliezer C. Rios | And 5 more authors.
Marine Biology | Year: 2015

Despite bottlenose dolphins being well studied in several regions around the world, there is very limited information about the reproduction of these animals in the Southwestern Atlantic Ocean (SWA). In this study, data from a long-term mark-recapture and stranding monitoring program were used to estimate life history traits of female bottlenose dolphins inhabiting the Patos Lagoon estuary, a sub-tropical coastal region in the SWA. From the analysis of 32,296 high-quality dorsal fin photographs, the fate of 37 individual females and 66 of their calves was tracked. Results supported a birth pulse dolphin community, with most births occurring during late spring and summer, in association with increasing water temperature and food supply. Female bottlenose dolphins first reproduced at a minimum age of 8 years. Mean inter-birth interval was 3 years (mode = 2), and fecundity was 0.11. A clear change in the δ13C and δ15N profiles in teeth from stranded carcasses near age 2 indicated the most probable weaning age. First and second year annual calf survival estimates were 0.84 (95 % CI 0.72–0.90) and 0.86 (95 % CI 0.74–0.94), respectively. No evidence was found to support that timing of birth plays a role in calf survival, suggesting that variability in water temperature and food resources within the year is unlikely to impact upon survival of calves. Older females reproduced at lower rates, suggesting an age-related decrease in reproductive fitness. At an individual level, marked variation in reproductive success was observed. Our findings highlight the importance of long-term studies for long-lived mammals to yield individual- and population-level parameters for demographic and viability analyses that are useful for conservation and management. © 2015, Springer-Verlag Berlin Heidelberg.

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