Collaborative Research: The impacts of the distribution of phenotypic effects and the distribution of pleiotropic costs on the genetics of natural adaptations

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Genes do not operate alone. They function as parts of large gene networks that work together to produce the organism traits we observe (phenotypes). However, not all genes contribute equally to a network and some genes may contribute to multiple traits. This difference among genes suggests that some genetic changes may have more impact than others; changes in a gene that has a large role in several traits presumably has more effect than changing a gene with a relatively minor role in a single trait. In general, large effect changes are thought to be bad for an organism. However, when that organism faces a strong evolutionary challenge, for example, an exposure to a pesticide or drug, eating a new food, encountering a pathogen, these large effect changes may be the only hope for its survival. This research will test hypotheses concerning the nature and predictability of evolving adaptive phenotypes by examining the phenotypic costs of genes having varying degrees of network interaction. This project will also provide hands-on training for students from underrepresented groups in key molecular and evolutionary concepts. This project tests the hypothesis that some genes, such as those that are central in networks, may be genetic 'hotspots' of trait evolution. To test this idea, this project uses the well-described fruit fly (Drosophila) olfactory system as a model genetic network. In flies, as with humans, the olfactory system evolves rapidly and is directly tied to some adaptations. Cutting edge genomic sequencing, analysis of chemosensory gene evolution, and ultrafine scale morphological analysis will be used to test whether adaptive ecological shifts are predictably associated with particular types of changes in the olfactory system. These predictions will then be tested on olfactory related phenotypes using the powerful genetic tools available in Drosophila.