Genetic Determination Vs. Flexibility: How Plastic Are Behaviors and Underlying Physiological Mechanisms in a System of Locally Adapted Populations?
Abstract
An important goal in evolutionary biology is to conceptually incorporate phenotypic plasticity into the framework of trait evolution. Here, I used a system of extremophile fish, Poecilia mexicana, locally adapted to all combinations of sulfidic and cave habitats, to test for genetic and plastic variation in energy metabolism and potential links between physiological and behavioral traits. Energy metabolism was predicted by habitat of origin, with cavefish showing higher routine metabolic rates, and sulfidic fish generally showing higher peak metabolic rates, although the extent to which was dependent on resource availability. Together variation in routine and peak metabolic rate lead to complex variation in metabolic scope, which varied depending on the presence of light and sulfide in natural populations as well as resource availability. A combination of resource availability, population of origin, and metabolic physiology (metabolic scope) also predicted male mate choice behavior, which was measured in two different ways: strength of preference for a preferred mate and the number of switches between two potential mates. Strength of preference depended on metabolic scope and the presence of sulfide in the population of origin, with sulfidic fish showing consistently higher strengths of preference, and strength of preference decreasing with metabolic scope overall. The number of switches between stimuli depended on presence of light in the population of origin, food treatment, and metabolic scope. Well-fed P. mexicana from cave populations increased their switching behavior with their metabolic scope. These results are part of a larger framework that elucidates the complex interaction between energetics, behavior, their genetic underpinnings, and aspects of the environment that affect the two phenotypes and the relationships between them.
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- OSU Theses [15752]