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Is the future female for turtles? Climate change and wetland configuration predict sex ratios of a freshwater species |
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| Authors: | H Patrick Roberts Lisabeth L Willey Michael T Jones Thomas S B Akre David I King John Kleopfer Donald J Brown Scott W Buchanan Houston C Chandler Phillip deMaynadier Melissa Winters Lori Erb Katharine D Gipe Glenn Johnson Kathryn Lauer Eric B Liebgold Jonathan D Mays Jessica R Meck Joshua Megyesy Joel L Mota Nathan H Nazdrowicz Kevin J Oxenrider Molly Parren Tami S Ransom Lindsay Rohrbaugh Scott Smith Derek Yorks Brian Zarate |
| Institution: | 1. Department of Environmental Conservation, University of Massachusetts, Amherst, Massachusetts, USA;2. Department of Environmental Studies, Antioch University New England, Keene, New Hampshire, USA
American Turtle Observatory, New Salem, Massachusetts, USA;3. Natural Heritage and Endangered Species Program, Massachusetts Division of Fisheries and Wildlife, Westborough, Massachusetts, USA;4. Smithsonian Conservation Biology Institute, Front Royal, Virginia, USA;5. U.S. Forest Service, Northern Research Station, Department of Environmental Conservation, University of Massachusetts, Amherst, Massachusetts, USA;6. Virginia Department of Wildlife Resources, Charles City, Virginia, USA;7. U.S. Forest Service, Pacific Northwest Research Station, Amboy, Washington, USA School of Natural Resources, West Virginia University, Morgantown, West Virginia, USA;8. Division of Fish and Wildlife, Rhode Island Department of Environmental Management, West Kingston, Rhode Island, USA;9. The Orianne Society, Tiger, Georgia, USA Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, Virginia, USA;10. Maine Department of Inland Fisheries and Wildlife, Augusta, Maine, USA;11. New Hampshire Fish and Game Department, Concord, New Hampshire, USA;12. The Mid-Atlantic Center for Herpetology and Conservation, Oley, Pennsylvania, USA;13. Pennsylvania Fish and Boat Commission, Bellefonte, Pennsylvania, USA;14. Biology Department, State University of New York, Potsdam, New York, USA;15. Department of Biological Sciences, Salisbury University, Salisbury, Maryland, USA;16. Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission, Gainesville, Florida, USA;17. Natural Heritage and Endangered Species Program, Massachusetts Division of Fisheries and Wildlife, Westborough, Massachusetts, USA Smithsonian Conservation Biology Institute, Front Royal, Virginia, USA;18. U.S. Forest Service, Pacific Northwest Research Station, Amboy, Washington, USA;19. Species Conservation and Research Program, Delaware Division of Fish & Wildlife, Delaware, USA;20. West Virginia Division of Natural Resources, Romney, West Virginia, USA;21. American Turtle Observatory, New Salem, Massachusetts, USA;22. Environmental Studies Department, Salisbury University, Salisbury, Maryland, USA;23. District of Columbia Department of Energy & Environment, Washington, District of Columbia, USA;24. Maryland Department of Natural Resources, Maryland, Wye Mills, USA;25. New Jersey Division of Fish and Wildlife, Lebanon, New Jersey, USA |
| Abstract: | Climate change and land-use change are leading drivers of biodiversity decline, affecting demographic parameters that are important for population persistence. For example, scientists have speculated for decades that climate change may skew adult sex ratios in taxa that express temperature-dependent sex determination (TSD), but limited evidence exists that this phenomenon is occurring in natural settings. For species that are vulnerable to anthropogenic land-use practices, differential mortality among sexes may also skew sex ratios. We sampled the spotted turtle (Clemmys guttata), a freshwater species with TSD, across a large portion of its geographic range (Florida to Maine), to assess the environmental factors influencing adult sex ratios. We present evidence that suggests recent climate change has potentially skewed the adult sex ratio of spotted turtles, with samples following a pattern of increased proportions of females concomitant with warming trends, but only within the warmer areas sampled. At intermediate temperatures, there was no relationship with climate, while in the cooler areas we found the opposite pattern, with samples becoming more male biased with increasing temperatures. These patterns might be explained in part by variation in relative adaptive capacity via phenotypic plasticity in nest site selection. Our findings also suggest that spotted turtles have a context-dependent and multi-scale relationship with land use. We observed a negative relationship between male proportion and the amount of crop cover (within 300 m) when wetlands were less spatially aggregated. However, when wetlands were aggregated, sex ratios remained consistent. This pattern may reflect sex-specific patterns in movement that render males more vulnerable to mortality from agricultural machinery and other threats. Our findings highlight the complexity of species' responses to both climate change and land use, and emphasize the role that landscape structure can play in shaping wildlife population demographics. |
| Keywords: | adaptive capacity agriculture climate change land use landscape structure temperature turtle wetland configuration |