The role of phenotypic plasticity in responses to environmental challenges.

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Phenotypic plasticity allows organisms to alter expression of traits in response to their environment, and has important consequences for the distributions, demography, and evolution of populations. Despite its broad importance, we are still learning how plasticity is induced by environmental factors, impacts fitness, and is shaped by natural selection. My long-term objective is to advance our understanding of the role of plasticity in mediating responses to environmental challenges using two complementary systems during the grant period: the challenge of parasites in a bird, and the challenge of changing temperatures in an insect. Parasites. Parasites affect almost every species on earth. We study plastic responses to parasites in a population of red-winged blackbirds with a high incidence of malarial infection. We will manipulate parasite infection in free-ranging birds and measure responses from the molecular to organismal level, within individuals and across generations. This work will provide one of the first field-based tests of the hypothesis that females prepare their young to cope with the challenge of malarial infection. Alternatively, the costs of infection might be transmitted across generations, amplifying its effects. Temperature. To make advances in our understanding of the evolution of plasticity, we recently expanded our research program to include studies of plastic responses in the burying beetle, Nicrophorus orbicollis. We will conduct controlled captive studies to determine how plasticity in multiple traits combines to determine individual performance across a range of temperatures. After identifying plastic traits that are important determinants of fitness, we will target those traits in an artificial selection experiment to evaluate the potential for plasticity to evolve in response to selection. Significance. This research program will allow us to make significant advances in addressing fundamental questions in the study of phenotypic plasticity. Do differences in plastic responses among individuals determine how well they cope with challenges? Do mothers prepare their offspring to cope with the challenges they have faced? How do plastic responses in multiple traits combine to impact fitness? Can plasticity evolve in response to selection? Our complementary approaches will generate significant advances in our understanding of how organisms cope with dynamic environments. Plastic responses to challenges impact individual fitness and scale up to determine the ability of populations and species to persist in the face of changing environments. As such, understanding plasticity is essential as anthropogenic challenges, like climate change and invasive and expanding parasites, increasingly threaten Canada's biodiversity. This research will draw from diverse lab and field techniques to answer our questions, providing strong, interdisciplinary training to HQP, and preparing them for a range of careers in biology.