Meeting Abstract

34.6  Friday, Jan. 4  Bathymetric Patterns of Genetic Variation: Implications for Evolution in the Deep Atlantic GLAZIER, A.E.*; ETTER, R.J.; JENNINGS, R.M.; University of Massachusetts, Boston; University of Massachusetts, Boston; University of Massachusetts, Boston amanda.glazier001@umb.edu

The deep-sea is a vast and complex ecosystem with a rich and highly endemic fauna. Most contemporary research has focused on the ecological mechanisms that allow coexistence of high alpha diversity. Few studies have considered how populations diverge or new species form to create this remarkable diversity. Recent work suggests that population divergence decreases with depth in response to reductions in biotic and abiotic heterogeneity below the continental shelf. Consistent with this hypothesis (referred to as the depth-differentiation hypothesis), species diversity, morphological divergence, and genetic differentiation all peak at bathyal depths, decreasing towards the abyss. Potential causes of this pattern include greater isolation of populations at bathyal depths due to topography, environmental heterogeneity, and depth-related variation in evolutionary rates. We test the depth-differentiation hypothesis in the western North Atlantic by comparing patterns of genetic variation between congeneric protobranch bivalve species pairs that have primarily bathyal (500-3000m) or abyssal (> 3000m) depth ranges. Comparing congeners controls for any taxonomic differences in evolutionary rates, ecology or life-history characteristics between more distantly related taxa. Multilocus analyses of both mitochondrial and nuclear loci are used to partition individuals into putative populations, estimate migration rates and test for divergence among these populations. Observed bathymetric patterns of genetic variation have important implications for evolution in the deep North Atlantic.