Collaborative research: Mating systems as mechanisms for resilience of species in which the environment determines whether they become male or female

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In some species, including many reptiles, birds, and fish, whether an animal becomes male or female depends on temperatures they are exposed to during early life. These species are likely to be affected by environmental changes, producing too many males or too many females when temperatures increase. How that might lead to increases or decreases in population abundance is not well understood. For example, a lack of males may not be a problem if a few males can mate with many females. Focusing on a population of the green sea turtle, the research will advance the fundamental knowledge of how the mating behaviors of these species can buffer against environmental change. This will be done using field surveys of male and female turtles and their nests, genetic measurements of parentage, and mathematical models of population change. The results will advance our understanding of how altered numbers of males and females affect the long-term population persistence of such species and their capacity to acclimate or adapt to skewed numbers of males or females. This will substantially improve frameworks to assess the impacts of environmental change on this type of species, improving management and conservation outcomes. This is important because sea turtles are some of the species most vulnerable to the impacts of environmental change. Other broader impacts of this research include training of early career researchers from underrepresented groups, public outreach, and dissemination of results in collaboration with a turtle conservation organization.Species in which the environment determines whether they become male or female are predicted to produce too many males or too many females with environmental change. This will ultimately affect long-term population viability and limit reproductive output. Despite the fundamental importance of understanding whether these species are resilient to environmental change, knowledge of the response of their mating systems and population dynamics to producing skewed numbers of males or female remains limited. This research will advance the understanding of how altered production of males or females affect the long-term population persistence of these species by combining multiple methods, using the green sea turtle (Chelonia mydas) population that nests in Brazil as a model. Field observations and genetic parentage analysis will quantify multiple aspects of the green sea turtle mating system (i.e., ratio of males to females that are ready to mate at any one time, ratio of the number of unique males and females that produce viable offspring, male natal philopatry, and breeding intervals) and linking these to reproductive success (egg numbers). These data will be used in an eco-evolutionary dynamic population model to assess persistence and the potential for adaptation. This research will take advantage of recent technological advancements in wildlife genetics, bio-logging devices, unmanned aerial vehicles, evolutionary modeling, and environmental forecasting. The outcome will be the first comprehensive examination of the potential for the mating system of species in which the environment determines whether they become male or female to provide resilience to environmental change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.