Elena Hidalgo, M.S. 2007

For her M.S. thesis, Elena studied population connectivity in two Caribbean sea slugs, Elysia velutinus (=tuca) and E. crispata, which differ in larval dispersal potential.  Elysia velutinus has short-lived, non-feeding larvae that settle only upon contacting the host alga Halimeda. In contrast, larvae of E. crispata metamorphose within their benthic egg capsules and have no free-swimming period.  Elena sequenced a portion of the cytochrome c oxidase I gene from slugs collected at a dozen sites across the Caribbean, ranging from Panama to Bermuda.  She found 6 highly divergent clades

within E. crispata that are largely restricted to different islands or regions,

with limited gene flow as expected given its non-dispersive larval stage. 

 

In contrast, there was comparatively little phylogeographic structure in E. velutinus.  Using population genetic methods of data analysis, Elena showed that most sites in the central Caribbean are connected and share a common haplotype, whereas populations at the range edges and in the northern Bahamas experience little gene flow with the rest of the basin.