DISSERTATION RESEARCH: Evolution of Reproductive Strategies

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When studying the evolution of reproductive strategies, or the collection of traits that contribute to reproduction, it is necessary to study how correlated traits respond to the same selective regime. In addition, maternal traits respond to selection. This study is designed to measure the adaptive nature of reproductive traits in a model oranism, the redbacked salamander Plethodon cinereus, with consideration of maternal effects. Plethodon cinereus exhibits the most derived reproductive strategy among amphibians, characterized by small clutch sizes, large egg sizes, solitary terrestrial nest sites, and maternal care of eggs. These traits were necessary adaptations for amphibians to become the first terrestrial vertebrates. This study is designed to determine correlations between reproductive traits and fitness (number of offspring produced) through the use of field studies and experimentation. Clutch sizes, egg sizes, egg-laying dates, and fitness will be recorded in an natural population, where maternal effects cannot be measured. Experiments will also be controlling for two important maternal traits, bosy size and nest site. By comparing the interrelationships among reproductive traits and fitness from these analyses, the strength and direction of selection acting on these can be assessed, and the way in which maternal traits mediate selection can be determined. It is this understanding of the physiological and ecological correlates among reproductive traits that will allow predictions of how organisms will respond to changes in their environment, which may be caused by global warning, habitat degradation, or human distrubance.