LINDNER, Alberto; Duke University: Evolution of shallow-water stylasterid corals (Cnidaria; Hydrozoa; Stylasteridae) from deep-sea ancestors

The fossil record indicates that the origin and diversification of marine taxa is often associated with onshore and offshore patterns of distribution. We investigated onshore-offshore trends in the evolution of stylasterid corals (family Stylasteridae), a group that embraces over 280 extant and fossil species. Our results, based on a review of fossil evidence and on a nuclear and mitochondrial DNA-based phylogeny, indicate that extant shallow-water stylasterid corals have originated from deep-sea ancestors. This shift from deep to shallow-water habitats has happened independently at least three times within the family (once within Distichopora and twice within Stylaster). Preliminary results, based mostly on mitochondrial DNA sequence data, also indicate that diversity of shallow-water stylasterid corals may be currently underestimated. Further studies on these shallow-water taxa are needed to more accurately determine biodiversity and thus test whether or not shifts from deep to shallow water habitats may be associated with diversification.