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Department of Ecology, Evolution, and Organismal Biology

Nicole Valenzuela

Visit my homepage at:
http://www.public.iastate.edu/~nvalenzu/

I am interested in the evolution and ecology of sex-determining systems in vertebrates. My research program ranges from studies of the ecological context to the genetic architecture that gave rise to and maintain alternative mechanisms of sex determination, and their evolutionary consequences. I am trying to understand the underlying ecological, physiological, behavioral, and molecular forces responsible for the persistence of temperature-dependent (TSD) or genotypic (GSD) sex determination over time. My research also includes the study life history evolution, ecological and conservation genetics of reptilian taxa, particularly turtles in the Neotropics and North America.

Current projects in my lab focus on the differences between the molecular mechanisms of temperature-dependent versus genotypic sex determination (GSD) in an evolutionary ecological context. My aim is to test whether molecular network involved in gonadal sexual differentiation in GSD and TSD species is essentially the same, but that qualitative/quantitative differences in expression of a few key genes in TSD species results in sex determination by temperature of egg incubation, rather than by genotypic constitution. We are also testing the alternative that differences in the regulatory regions of otherwise common sex-determining genes could be critical. To address these questions we use comparative genomic analyses at several levels. These include analyses of gene expression patterns in embryos of TSD and GSD species prior to and during the embryological stages of sex-determination and gonadal differentiation; bioinformatic approaches; and comparative analyses of molecular and chromosomal evolution. Other ongoing projects in the lab include the population genetics of Podocnemis unifilis in South America, and the life history/sex determination of Podocnemis lewyana in Colombia.