Blog de la Copa Carey

  • Liles et al. 2018_Reubicación de huevos y sensibilidades térmicas (Íngles)

    - November 14, 2019

    Potential limitations of behavioral plasticity and the role of egg relocation in climate change mitigation for a thermally sensitive endangered species

    Anthropogenic climate change is widely considered a major threat to global biodiversity, such that the ability of a species to adapt will determine its likelihood of survival. Egg‐burying reptiles that exhibit temperature‐dependent sex determination, such as critically endangered hawksbill turtles (Eretmochelys imbricata), are particularly vulnerable to changes in thermal regimes because nest temperatures affect offspring sex, fitness, and survival. It is unclear whether hawksbills possess sufficient behavioral plasticity of nesting traits (i.e., redistribution of nesting range, shift in nesting phenology, changes in nest‐site selection, and adjustment of nest depth) to persist within their climatic niche or whether accelerated changes in thermal conditions of nesting beaches will outpace phenotypic adaption and require human intervention. For these reasons, we estimated sex ratios and physical condition of hatchling hawksbills under natural and manipulated conditions and generated and analyzed thermal profiles of hawksbill nest environments within highly threatened mangrove ecosystems at Bahía de Jiquilisco, El Salvador, and Estero Padre Ramos, Nicaragua. Hawksbill clutches protected in situ at both sites incubated at higher temperatures, yielded lower hatching success, produced a higher percentage of female hatchlings, and produced less fit offspring than clutches relocated to hatcheries. We detected cooler sand temperatures in woody vegetation (i.e., coastal forest and small‐scale plantations of fruit trees) and hatcheries than in other monitored nest environments, with higher temperatures at the deeper depth. Our findings indicate that mangrove ecosystems present a number of biophysical (e.g., insular nesting beaches and shallow water table) and human‐induced (e.g., physical barriers and deforestation) constraints that, when coupled with the unique life history of hawksbills in this region, may limit behavioral compensatory responses by the species to projected temperature increases at nesting beaches. We contend that egg relocation can contribute significantly to recovery efforts in a changing climate under appropriate circumstances.

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    Liles et al. 2019_Egg relocation and thermal sensitivity

     

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  • Gaos et al. 2018_Prevalencia de poliginia en tortugas carey en Bahia de Jiquilisco, El Salvador (Íngles)

    - November 14, 2019

    Prevalence of polygyny in a critically endangered marine turtle population

    Genetic analyses of nuclear DNA (e.g., microsatellites) are a primary tool for investigating mating systems in reptiles, particularly marine turtles. Whereas studies over the past two decades have demonstrated that polyandry (i.e., females mating with multiple males) is common in marine turtles, polygyny (i.e., males mating with multiple females) has rarely been reported. In this study we investigated the mating structure of Critically Endangered hawksbill turtles (Eretmochelys imbricata) at Bahía de Jiquilisco in El Salvador, one of the largest rookeries in the eastern Pacific Ocean. We collected genetic samples from 34 nesting females and hatchlings from 41 clutches during the 2015 nesting season, including one nest from each of 27 females and two nests from seven additional females. Using six highly polymorphic microsatellite loci, we reconstructed the paternal genotypes for 22 known male turtles and discovered that seven (31.8%) sired nests from multiple females, which represents the highest polygyny level reported to date for marine turtles and suggests that this is a common mating structure for this population. We also detected multiple paternity in four (11.8%) clutches from the 34 females analyzed, confirming polyandrous mating strategies are also employed. The high level of polygyny we documented suggests there may be a limited number of sexually mature males at Bahía de Jiquilisco; a scenario supported by multiple lines of empirical evidence. Our findings highlight key management uncertainties, including whether polygynous mating strategies can compensate for potential ongoing feminization and the low number of adult males found for this and possibly other marine turtle populations.

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    Gaos et al. 2018_Prevalence of polygyny in hawksbill turtles

     

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  • Gaos et al. 2018_Contribuciones de sitios de anidación a sitios de forrajeo_mtDNA (Íngles)

    - November 14, 2019

    Rookery contributions, movements and conservation needs of hawksbill turtles at foraging grounds in the eastern Pacific Ocean

    Understanding the spatial ecology of wide-ranging marine species is fundamental to advancing ecological research and species management. For marine turtles, genetic studies using mitochondrial DNA (mtDNA) markers have proven invaluable to characterize movement, particularly between rookeries (i.e. nesting sites) and foraging grounds. Hawksbill turtles Eretmochelys imbricata are a globally threatened species whose conservation status is particularly precarious in the eastern Pacific Ocean. Recent research in the region has identified unique life history characteristics, including highly restricted movements, the use of mangrove estuaries for foraging and nesting, as well as a regional pattern of natal foraging philopatry (NFP). For this study, we used mtDNA sequences and mixed-stock analysis of hawksbills from 8 designated foraging grounds and 5 primary rookeries to evaluate stock composition at each foraging ground, assess how stock contributions are affected by the NFP life history strategy, and search for evidence of unidentified rookeries. Although we found evidence supporting the NFP pattern at most foraging grounds, results indicated important site-specific variability at particular foraging grounds. We also found discrepancies among the haplotype frequencies of several foraging grounds and rookeries, as well as the presence of several orphan haplotypes, suggesting undiscovered hawksbill rookeries likely remain in the eastern Pacific. Our findings contextualize the prevalence and scale of the NFP life history strategy and provide insights that can be directly applied to future ecological research and species management and conservation.

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    Gaos et al. 2018_Rookery contributions to foraging grounds using mtDNA

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