Meeting Abstract

44.10  Saturday, Jan. 5  Genetic diversity and biogeography of Symbiodinium from sea anemones, Aiptasia spp. XIANG, Y.*; SANTOS, S.R.; Auburn University; Auburn University xiangyu@auburn.edu

Symbiotic dinoflagellates in the genus Symbiodinium, commonly referred to as zooxanthellae, are single-celled protists which play important roles in the nutrition and physiology of many marine invertebrates. Recently, Symbiodinium diversity and phylogenetics have been intensively studied due to the introduction of molecular approaches. However, little is known concerning the population genetics of Symbiodinium in many hosts, including sea anemones in the genus Aiptasia, which have become a system for studying the invertebrate-dinoflagellate endosymbiosis. In order to address this issue, we first utilized restriction fragment length polymorphisms (RFLPs) to examine the variation and distribution of Symbiodinium clades in Aiptasia from around the world. We found that Aiptasia from most sampling locations harbor members of Symbiodinium Clade B while Aiptasia from the Florida Keys host either members of Clade A, B or mixtures of both A and B. In addition, six microsatellite loci specific for Symbiodinium Clade B were utilized on 276 Aiptasia samples to quantify genetic differences among symbiont populations. From these data, strong population structure was revealed across both short (i.e., 30 km) and long (Okinawa vs. Florida) geographic ranges. Interestingly, an identical Symbiodinium Clade B genotype was found to be shared in Aiptasia populations from Japan, Hawaii and Mexico, suggesting potential population connectivity between these locations. Lastly, background populations of Symbiodinium Clade B were detected in Florida Aiptasia whose RFLPs were indicative of only Symbiodinium Clade A, indicating that Aiptasia can harbor multiple Symbiodinium clades simultaneously and that some symbionts may be present at low levels.