Phylogenetic relationships among the clownfish-hosting sea anemones.

The clownfish-sea anemone symbiosis has been a model system for understanding fundamental evolutionary and ecological processes. However, our evolutionary understanding of this symbiosis comes entirely from studies of clownfishes. A holistic understanding of a model mutualism requires systematic, biogeographic, and phylogenetic insight into both partners. Here, we conduct the largest phylogenetic analysis of sea anemones (Order Actiniaria) to date, with a focus on expanding the biogeographic and taxonomic sampling of the 10 nominal clownfish-hosting species. Using a combination of mtDNA and nuDNA loci we test (1) the monophyly of each clownfish-hosting family and genus, (2) the current anemone taxonomy that suggests symbioses with clownfishes evolved multiple times within Actiniaria, and (3) whether, like the clownfishes, there is evidence that host anemones have a Coral Triangle biogeographic origin. Our phylogenetic reconstruction demonstrates widespread poly- and para-phyly at the family and genus level, particularly within the family Stichodactylidae and genus Stichodactyla, and suggests that symbioses with clownfishes evolved minimally three times within sea anemones. We further recover evidence for a Tethyan biogeographic origin for some clades. Our data provide the first evidence that clownfish and some sea anemone hosts have different biogeographic origins, and that there may be cryptic species of host anemones. Finally, our findings reflect the need for a major taxonomic revision of the clownfish-hosting sea anemones.

Lack of Evidence for Natural Wolbachia Infections in Aedes aegypti (Diptera: Culicidae).

Wolbachia is a genus of endosymbiotic bacteria that infects 66% of all insect species. Its major impact on insects is in reproduction: sterility, production of one sex, and/or parthenogenesis. Another effect was discovered when the disease-transmitting mosquito, Aedes aegypti Linnaeus (Diptera: Culicidae), was infected with Wolbachia isolated from Drosophila: infected female mosquitoes became less capable of transmitting diseases such as dengue fever and chikungunya. This has led to releases of Ae. aegypti carrying Wolbachia in an attempt to control disease. An open question is whether there are natural Wolbachia infections of this mosquito. We assayed DNA from 2,663 Ae. aegypti from 27 countries on six continents, 230 from laboratory strains, and 72 Aedes mascarensis MacGregor (Diptera: Culicidae) for presence of Wolbachia DNA. Within the limits of our polymerase chain reaction-based assay, we found no evidence of Wolbachia, suggesting that natural infections of this endosymbiont are unlikely to occur throughout the worldwide distribution of Ae. aegypti.