Meeting Abstract

52.2  Jan. 6  GENETIC VARIATION AND PHENOTYPIC PLASTICITY OF THE GORGONIAN Plexaura flexuosa IN PUERTO RICO PRADA, Carlos*; SCHIZAS, Nikolaos; YOSHIOKA, Paul; University of Puerto Rico Mayaguez cprada@cima.uprm.edu

Caribbean octocorals are relatively abundant and visually dominant in low relief hard ground habitats with preference for high water motion areas. As other Anthozoans, octocorals display a tremendous phenotypic plasticity. The common Caribbean gorgonian Plexaura flexuosa is found in many depths and habitats, showing high levels of morphological variation in colony, branch and sclerite size. Nested ANOVAs for each character showed significant differences (p<0.001) of colonies among and within 7 reefs and deep and shallow habitats. A discriminant function analysis correctly classified (>75%) the colonies for each environment. Higher scores were found when colonies were assigned to either deep or shallow regardless the reef. P. flexuosa in shallow areas (<5m) exposed to high water motion, were characterized by taller, more plumose colonies, thicker branches, bigger calices and smaller sclerites than those found in deeper areas (>17m) exposed to low water motion. Reciprocal transplants showed that variation in sclerite size between colonies in shallow and deep areas is due, in part, to ecophenotypic response to water motion. The sclerites of shallow water colonies became larger when transplanted to deeper water and vice versa. Neither of the two transplanted groups reached the average size of individuals originally found in each depth. AMOVA analysis of the mitochondrial Msh gene and the nuclear 18S/ITS region showed significant differences among the shallow and deep populations. The morphological variability among shallow and deep P. flexuosa is due to a combined effect of environmentally induced plasticity and genetic differentiation. The data suggest that P. flexuosa represents a complex of at least two cryptic taxa.