A common paradigm in marine genetics asserts that intertidal species with free-living, planktonic larvae can disperse longer distances than species that develop directly into adults. This pattern, however, does not always hold true. In fact, many species without free-living larvae do manage to disperse long distances; these species may be dispersing by clinging to detached pieces of algae (i.e. rafting). Many shallow-water marine species have been observed rafting on algae quite far from shore; whether these organisms ever reach another population, however, is unknown. The goal of this study is to determine whether rafting is an effective means of dispersal for coastal marine species without free-living larvae. This study will focus on six species of amphipods (small, shrimp-like crustaceans that lack free-living larvae) in the North Atlantic. Two species are common rafters, two are rare rafters, and two have never been observed rafting. Using mitochondrial and nuclear genes and newly-developed coalescent methods of analysis, this study will determine whether there is a correlation between gene flow and rafting frequency in these species.
Understanding dispersal is crucial to understanding genetic diversity within species. Rafting is a means of dispersal that has rarely been studied, as in many species it is confounded by other dispersal methods such as free-living larvae. This grant will provide funding for a female graduate student to finish her dissertation.
