Meeting Abstract
Environmental differences affect genetic and phenotypic variation among individuals. For Fundulus heteroclitus there are meaningful environmental differences within a single estuary; upper-tidal ponds have higher daily maximum temperatures and lower nightly oxygen concentration than do tidal creeks or the basins, which these creeks drain into. Individuals from three microhabitats 1) tidal basins, 2) inter-tidal creeks, and 3) tidal ponds share the same breeding areas, thus one might expect the populations to be panmictic. Yet, mark-recapture studies indicate that fish have high habitat fidelity to each of the three microhabitats. To examine any microhabitat differences in genotypes that might be the result of natural selection, individuals from the 3 different microhabitat types from 3 replicate locations along the New Jersey Coast (Mantoloking, Tuckerton, and Stone Harbor) were genotyped at more than 10,000 loci using genotyping-by-sequencing (GBS). Dependent on replicate location, analyses identified between 250-600 loci (p-val < 0.01, FDR = 0.01) with significant FST values between populations of tidal basin and pond resident fish. These loci may be adaptively important and, suggest that selection is affecting allele frequencies over very small geographical distances. This research will allow for the identification of potentially adaptively relevant genes, and further investigates the molecular basis for how the physiological response to even slightly different environments causes a change in genetic structure.
