Meeting Abstract

S3.2  Tuesday, Jan. 4  What have DNA molecules told us about speciation in the sea? LESSIOS, Harilaos; Smithsonian Tropical Research Institute Lessiosh@post.harvard.edu

The study of speciation of marine organisms has received the same boost from molecular information as that of terrestrial ones. Reconstruction of phylogenetic histories, in addition to providing the essential information as to who has separated from whom, has in many cases revealed the mode of speciation, providing evidence in favor of allopatric divergence followed by reproductive isolation. Because members of many marine groups shed their gametes in the water without courtship, species recognition often occurs at the level of molecular interactions between egg and sperm. This property makes reproductive isolation (and thus speciation) in marine invertebrates easier to study at the molecular level than that of many “model” terrestrial organisms. It has led to the characterization of some of the molecules involved in such interactions, and to the study of the manner in which they have evolved.. Abalone lysin and its receptor, acrosomal mussel M7 lysin, and acrosomal sea urchin bindin are “speciation molecules,” important in reproductive isolation. Each of these molecules evolves very differently from the others, and where variation between taxa has been studied (in bindin) the same molecule evolves differently in different genera.