Climatic and geographic predictors of life history variation in Eastern Massasauga (Sistrurus catenatus): A range-wide synthesis


Eric T. Hileman, Northern Illinois University
Richard B. King, Northern Illinois University
John M. Adamski, Seneca Park Zoo
Thomas G. Anton, Field Museum of Natural History
Robyn L. Bailey, Cornell Lab of Ornithology
Sarah J. Baker, Illinois Natural History Survey
Nickolas D. Bieser, Indiana University-Purdue University Fort Wayne
Thomas A. Bell, New York State Department of Environmental Conservation
Kristin M. Bissell, State of Michigan
Danielle R. Bradke, Grand Valley State University
Henry Campa, Michigan State University
Gary S. Casper, University of Wisconsin-Milwaukee
Karen Cedar, Ojibway Nature Centre
Matthew D. Cross, Bowling Green State University
Brett A. DeGregorio, University of Illinois Urbana-Champaign
Michael J. Dreslik, Illinois Natural History Survey
Lisa J. Faust, Lincoln Park Zoo
Daniel S. Harvey, University of Illinois Urbana-Champaign
Robert W. Hay, Turtles for Tomorrow
Benjamin C. Jellen, Urban Chestnut Brewing Company
Brent D. Johnson, SUNY College of Environmental Science and Forestry
Glenn Johnson, SUNY Potsdam
Brooke D. Kiel, Grand Valley State University
Bruce A. Kingsbury, Indiana University-Purdue University Fort Wayne
Matthew J. Kowalski, Chesapeake Bay Foundation
Yu Man Lee, Michigan State University
Andrew M. Lentini, Toronto Zoo
John C. Marshall, Indiana University-Purdue University Fort Wayne
David Mauger, Lake County Forest Preserves
Jennifer A. Moore, Grand Valley State University
Rori A. Paloski, Wisconsin Department of Natural Resources
Christopher A. Phillips, Illinois Natural History Survey
Paul D. Pratt, Ojibway Nature Centre

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Elucidating how life history traits vary geographically is important to understanding variation in population dynamics. Because many aspects of ectotherm life history are climate-dependent, geographic variation in climate is expected to have a large impact on population dynamics through effects on annual survival, body size, growth rate, age at first reproduction, size-fecundity relationship, and reproductive frequency. The Eastern Massasauga (Sistrurus catenatus) is a small, imperiled North American rattlesnake with a distribution centered on the Great Lakes region, where lake effects strongly influence local conditions. To address Eastern Massasauga life history data gaps, we compiled data from 47 study sites representing 38 counties across the range. We used multimodel inference and general linear models with geographic coordinates and annual climate normals as explanatory variables to clarify patterns of variation in life history traits. We found strong evidence for geographic variation in six of nine life history variables. Adult female snout-vent length and neonate mass increased with increasing mean annual precipitation. Litter size decreased with increasing mean temperature, and the size-fecundity relationship and growth prior to first hibernation both increased with increasing latitude. The proportion of gravid females also increased with increasing latitude, but this relationship may be the result of geographically varying detection bias. Our results provide insights into ectotherm life history variation and fill critical data gaps, which will inform Eastern Massasauga conservation efforts by improving biological realism for models of population viability and climate change.



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