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

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

The Effect of Processes and Incentives on Acquisition Cost Growth

Proceedings Paper (for Acquisition Research Program)Cost growth continues to be a serious concern in major acquisition programs. A variety of causes have been identified for cost growth, including low initial cost estimates, complex acquisition processes, and immature technologies. Incentive-based systems have been employed in an attempt at cost savings, with mixed results at best. This paper examines the role of process and incentive characteristics in cost growth. In particular, we study process concurrency, types of incentive contracts employed and the transfer point from cost-plus to fixed-price contracts, and the resulting effects on cost growth in the F-35 Joint Strike Fighter program. The F-35 program currently is in low-rate initial production. The emerging paradigm of organizational simulation is used in this study, since it combines process representations to model acquisition processes and agent representations to model multi-actor behavior, including reaction to incentives. Simulation experiments are conducted and analyzed to determine the effects of the factors described above on cost growth.Naval Postgraduate School Acquisition Research ProgramApproved for public release; distribution is unlimited

Date Approved ACKNOWLEDGEMENTS I am indebted to the following people for their insightful comments and helpful dis-

I would also like to thank my advisors, Michael K. Reiter and Adrian Perrig, for their guidance and inspiration during this work. Without their support this project would not have happened. career. I am indebted to my family and friends for their support throughout my educational ii