Meeting Abstract

30.1  Friday, Jan. 4  How quickly are eyes lost? A phylogenetic study of deep sea and shallow water cylindroleberidid ostracods. SYME, A.E.**; OAKLEY, T.H.O.; Univ. of California, Santa Barbara; Univ. of California, Santa Barbara anna.syme@gmail.com

Animals migrating to the deep sea often lose their eyes over evolutionary timescales. How fast can it happen? And, contrary to Dollo�s �law�, can they get their eyes back? We studied these questions using ostracod crustaceans: small, bivalved, predominantly aquatic animals with cosmopolitan distributions and an extensive fossil history. One group of ostracods has compound lateral eyes and is an interesting study group for questions of eye evolution. We focused on one family of these ostracods, Cylindroleberididae, with well-preserved fossil representatives and more than 200 living species. This family includes some species without lateral eyes – presumably as a result of evolution in dark environments such as the deep sea. Using a three-gene molecular phylogeny as a framework, we estimated the rates of loss (and gain) of the lateral eye in this group. Such estimates are sensitive to the particular model used, and we investigated this more fully using Bayesian statistics. Rate estimation reveals interesting details about morphological evolution; in this case, whether eye re-gain is possible and whether rates of change are high.