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From the Office of Dr. David Crews
Focus of Research
Note: (numbers in parentheses indicate publication number)

 

3. The origins of phenotypic and neural plasticity (R01 MH 57874)

Phenotypic plasticity refers to the process by which the environment induces different phenotypes from a given genotype. The mechanisms underlying plasticity can either be committed and fixed or labile and reversible or can vary among or within individuals. When we consider that even in species with sex chromosomes each individual possesses all of the genes necessary to develop the phenotype of both sexes, it becomes apparent that the process of sexual differentiation represents a form of phenotypic plasticity.

Using the leopard gecko as the animal model system, I am able to determine how the experience of temperature during embryogeny affects the phenotype of the adult organism, including sexual and aggressive behaviors and the structure and activity of brain areas mediating these behaviors (c.f., 226, 228, 234, 239, and 251). For example, I have established that incubation temperature accounts for much of the variation observed among individuals in morphology, growth, endocrinology, neural activity, and neuroanatomy. Some sociosexual behaviors and brain measures are affected directly by incubation temperature, whereas others are influenced by both incubation temperature as well as gonadal sex. The theoretical contributions of this work relate to a fundamental question in neuroethology, namely, what are the factors that determine individual variability, particularly as it relates to sexually dimorphic behaviors. Thus, this animal model allows us to separate environmental effects from those imposed by the genetically determined sex of the individual. Findings to date have already proven important in furthering our understanding of the role of environmental factors in sex hormone mediated neural plasticity and have been extended to mammals (e.g., 227).