Test of the Causes of Evolved Differences and Plasticity in Growth and Development Rates of Passerines Offspring Across Three Continents

PhD Dissertation, Riccardo Ton

The two overarching aims of my dissertation are: a) to test the role of temperature in causing the broad pattern of interspecific variation in development rates among ectothermic embryos; b) to explore the role of interspecific variation in metabolism of endothermic offspring, potentially resulting from the differential selective pressure of predation, in contributing to interspecific variation in growth rate. To achieve these goals, I use an experimental and comparative approach among passerine species on three different continents. I spent three field seasons of data collection in a montane tropical forest in Borneo Malaysia and three seasons in a high altitude riparian system in Arizona. Moreover, I obtained funding to support one season of data collection in a third southern temperature field site in South Africa in September, 2014. I experimentally heated nests of 8 species covering a gradient of embryonic growth rates ranging from 12 to 25 days of incubation. I measured the metabolic rate of 82 embryos and 235 nestlings of these and other species.