DISSERTATION RESEARCH: Sex-biased dispersal: mechanisms and consequences in changing environments

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One of the biggest challenges that ecologists face is making accurate predictions about how the natural world will change over time. As humans continue to alter landscapes, it is important to understand how organisms will respond to these changes and how resilient the natural world will be. Scientific research in this area serves a practical purpose, for gauging the potential costs of growth and expansion, while it advances fundamental understanding of the natural world. This project will develop a novel approach to examine how organisms respond to change that will provide greater nuance and predictive power for a diverse organisms facing wide-ranging environmental change. Dispersal is an important process that affects the ecology and evolution of organisms but the consequences of individual variation in dispersal ability are not well understood. One particularly common form of intraspecific variation in dispersal occurs between males and females of a species, and this project will investigate how sex-biased dispersal affects the persistence of metapopulations in changing environments. Previous studies by the authors have found that adult female and larval odonates, commonly known as dragonflies and damselflies, are highly constrained by their environment, while adult males often dispersed into unsuitable habitat. This suggests that biases exist for both dispersal distance and for habitat choosiness. In order to investigate the specific behavioral mechanisms behind this differing dispersal behavior, a reciprocal transplant experiment will be performed. Emerging adult odonates will be raised in artificial mesocosms, captured and marked, then released at mesocosms containing unsuitable habitat. Settlement of marked individuals close to the release location, regardless of the environmental qualities of that habitat, will suggest that dragonflies are not choosy in their dispersal behavior, but rather settle close to home. This behavior has important consequences in changing environments. By linking pattern, mechanism, and generality, this project will be providing more evidence of the ecological importance of gender-biased dispersal and of individual variation more generally. The project will significantly advance training of a doctoral student by providing the opportunity to test newly-developed models with field experiments. The investigators will present results to the public through existing programs such as Science Under the Stars, Travis Audubon Society, Capital Area Master Naturalists, and the Austin Butterfly Forum - local organizations committed to raising public awareness of natural communities.