Meeting Abstract
Amphipoda is a highly successful crustacean order with more than 8,000 described species inhabiting a wide array of marine, freshwater, and moist terrestrial environments. This ecological diversity is reflected in similarly high levels of morphological variation. The amphipods have traditionally been organized into four groups, the Hyperiidea, Gammaridea, Caprellidea, and Ingolfiellidea. Hyperiidea is an abundant and diverse group consisting of about 350 described species. No single common morphological synapomorphy unites the group. Instead, hyperiid amphipods are defined only by an exclusively pelagic existence. Previous morphological and molecular studies have led to uncertainty in the monophyly of hyperiids and the possibility of convergent evolution of pelagic lifestyles in multiple amphipod lineages. Like many midwater animals, hyperiids possess a wide range of adaptations to this unique environment, for example, a vast array of visual strategies. In order to understand these adaptations, it is necessary to study complex relationships among environment, morphology, physiology and behavior, in an evolutionary context. Such analysis hinges on an accurate phylogenetic hypothesis onto which these patterns can be mapped. Here we present preliminary results of a multi-gene phylogenetic analysis of all publicly available amphipod sequences for 3 nuclear (18S, 28S, and H3) and 2 mitochondrial loci (COI and 16S). This is the largest analysis, to date, aimed at addressing the question of hyperiid monophyly and will be used to inform taxon sampling for an ongoing transcriptome-based phylogenomic study.
