Phylogenetics of cytoplasmically inherited microorganisms of arthropods.

Associations with cytoplasmically inherited microorganisms are fundamental to the ecology and reproductive biology of many insects. Molecular phylogenetics now provides a window into the previously obscure history of these associations. This approach has recently yielded striking findings for two cases: the mutualistic endosymbionts of aphids and relatives, and some of the cytoplasmically inherited organisms that induce reproductive abnormalities in various arthropods. These examples provide useful reference points for future extensions of molecular phylogenetic methods to other prokaryote-eukaryote associations.