Life-history and conservation of amphibians and reptiles

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I am investigating how major features of a species' life history, such as number and size of offspring, age at maturity, longevity and iteroparity have evolved. My methodological focus is to examine how these features vary within and among populations and species. I have concentrated on turtles, snakes and frogs because these groups have extended lifespans in cooler environments. My approach is to combine long-term data collection with short-term experiments; in both cases the key is that I am testing hypotheses with long-term data on marked individuals. Such data allow me to compare changes in individuals over time with changes within and among populations. My primary study populations occur near their species' northern limits of distribution. Standard morphometric and demographic measurements are taken annually and responses to manipulations of temperature, moisture, food, population density and sex ratio are measured to test hypotheses that explain different patterns of life history. Currently, I am examining how temperatures control distribution, how sex ratio is maintained when sex is determined by environment, how females select mates and why some vertebrates continue to grow throughout their lives. I am particularly interested in applying my research to conservation of reptiles and testing how life history affects vulnerability of long-lived species to anthropogenic pressures. In addition, our long-term data allow us to test for effects of warming temperatures on specific demographic and life history traits.