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Tanya McKitrick
Biology

Bill Bradshaw and Chris Holzapfel, Mentors

The Evolution of the Genetic Architecture Underlying Latitudinal Phenotypic Traits within the Pitcher-Plant Mosquito, Wyeomyia smithii

The genetic architecture underlying a trait refers to the network of genes and their interactions that result in its phenotypic variation, the principal target of natural selection. Historically, geneticists presumed that additivity and dominance were the most important modes of gene action involved in evolution. Recently, however, polygenic interactions (epistasis) have been considered to be more evolutionarily significant than previously thought. We examined the genetic architecture underlying traits that vary across a latitudinal gradient in the pitcher-plant mosquito, Wyeomyia smithii, using line crosses involving a northern, a mid-latitude and two southern populations. These traits included stage of diapause (winter dormancy), number and size of anal papillae, ovarian maturation, oviposition site, and egg size. The hybrids resulting from the line crosses allowed us to determine which modes of gene action (additive, dominance or epistasis) are most important for these traits and the degree to which epistasis has played a role in their evolution.