Meeting Abstract

S8-2.2  Saturday, Jan. 5  Visual elements and the evolution of the decapods PORTER, M.L.*; CRONIN, T.W.; Univ. of Maryland Baltimore County; Univ. of Maryland Baltimore County porter@umbc.edu

Decapods possess a greater variety of eye types than other crustacean groups. While the evolution of this diversity has been studied in light of decapod relationships, few studies have evaluated decapod visual elements � including morphological components of the compound eye and molecular markers such as the visual pigment gene, opsin – as potential phylogenetic characters. We have investigated molecular and morphological characters of the decapod visual system to evaluate their potential for phylogenetic signal. While many decapod species previously investigated contain reflecting superposition eyes, visual modifications, such as the accessory eye in carideans, may provide characters supporting the current infraorder structure. Species within the Anomala and Brachyura both possess at least three different types of compound eyes, which may provide characters supporting major lineages within these species-rich infraorders. The opsin sequences so far isolated form three distinct groups: a general clade of decapod middle-wavelength opsins, a clade composed only of sequences isolated from brachyurans (Portunidae and Varunidae), and an uncharacterized opsin from Homarus americanus. Within the middle-wavelength opsins, there appear to be multiple gene duplication events confounding their use as phylogenetic markers. The remaining two groups of decapod opsins currently contain few sequences, and require more characterization before determining phylogenetic potential.