Meeting Abstract
Marine invertebrates exhibit astonishing levels of morphological diversity in their adult forms. Their larvae, however, can be broadly grouped into a few developmental modes defined by how they acquire the nutrients they need to reach adulthood. While most species are fixed for developmental mode, there are a handful of species that are dimorphic, producing both lecithotrophic (yolk-feeding) and planktrophic (plankton-feeding) larvae. These dimorphic species allow detailed investigations into the genetic and environmental factors underlying the evolution of larval type, unhindered by additional cross-species differences. The species Alderia willowi, is plastic for larval type. Larval type in A. willowi is influenced by season, with more lecithotrophic larvae produced in summer and more planktotrophic larvae in winter. I examined individual plasticity for larval type in A. willowi by subjecting lab reared individuals to changes in salinity and temperature. I chose salinity and temperature that mimic mean summer (20 °C, 32ppt) and winter (16 °C, 16ppt) conditions. I found a great deal of variation in individual plasticity that was not subject to an overall family-level response. I raised several lines of self-fertilized offspring to examine the effect of reduced genetic diversity on individual response to environment. These lines were exposed to changes in salinity and temperature and monitored for larval type. These results suggest a G X E interaction that involves multiple small effect genes. From these inbred lines I have selected individuals that have crossing-reaction norms, and will use these lines to form F2 mapping population. These mapping populations will allow me to identify the number and location of genes involved in larval type in A. willowi.
