Intellectual merit. Genes interact with each other and with the environment to produce the organismal phenotypes upon which natural selection operates. These GxG and GxE interactions can influence responses to natural selection to a significant degree. This proposal outlines a project to measure the impact of genetic and environmental influences on phenotypic variation within an exceptionally welldefined network of interacting genes. The subject of these analyses is the skeletogenic gene network and resulting larval skeleton of the sea urchin Strongylocentrotus purpuratus. The impact of genetic and environmental variation will be assayed at different levels of biological organization: molecular phenotypes will be measured as allele-specific transcription and organismal phenotypes will measured through morphometric analyses of anatomy. The Specific Aims are as follows: 1. Measure the genetic basis for network phenotypes. An 8 x 8 cross will be used to estimate genetic contributions to phenotypic variation, to identify genes whose expression contributes the most to phenotypic variation, and to measure the degree to which anatomical variation is buffered from variation in underlying gene expression. 2. Measure gene network-by-environment interactions. Manipulation of food level will be used to characterize the response of the gene network to changes in a key environmental variable, to measure how much genetic variation influences this response, and to identify specific genes that mediate phenotypic plasticity. Together, the results of these analyses will provide detailed information about the origins of complex trait variation across a well defined gene network and its anatomical product in a wild population, and provide insights into how variation in developmental processes affects ecologically relevant organismal phenotypes.
Broader impacts. The influence of genetic and environmental factors on phenotypic variation has considerable general importance. This topic is a critical part of understanding evolutionary processes, but also has broad significance for medical and agricultural studies. Integrating an understanding of gene networks and gene expression into such studies represents a challenge, but also an area of significant opportunity. In addition, the proposed research will involve training young scientists in modern laboratory methods and analytical approaches. Training will continue to involve scholars at several levels of education, from high school students to post-doctoral researchers, as during prior funding.
