The evolutionary relationship of the Millepores in the Western Atlantic has been problematic for years. Current taxonomic distinction is based mainly upon morphological characters and habitat. Millepora complanta is found in shallower, more turbulent waters and is composed of sturdy blade-like colonies whereas M. alcicornis has delicate branching spires and inhabits deeper or more sheltered areas. However, the presence of a wide range of intermediate forms calls the currently accepted phylogeny into question. Genetic analysis of the Millepores conducted in our lab has demonstrated the existence of two distinct cryptic clades that are independent of morphology and habitat.
Millepores have a symbiotic relationship with an algal zooxanthellate called Symbiodinium. Our premise is that zooxanthellae-coral host specificity can be used as a diagnostic tool to understand the phylogenetic relationship between the Millepores. In order to determine if there is host specificity between Symbiodinium and Millepora, we sequenced the rDNA internal transcribed spacer regions of Symbiodinium from various coral hosts. The sequenced samples included both duplicate sequences of the same individual as well as sequences from multiple individuals. Within individual sequence differences tended to be less than between-individual variation and no host specificity was found among the samples analyzed.
The next step in our research is to isolate and sequence the common and rare variants from each coral host in order to determine if any of the symbionts display host specificity with the Millepores. We hope our efforts lead to a comprehensive understanding of the phylogenetic relationships in the Millepore complex.
Sophie Gaynor, ’12
Majors: Mathematics and Statistics, Biology
Elise Mead, ’12
Majors: Biochemistry and Molecular Biology, Spanish
Sponsor: Craig Tepper