Vanderbilt School of Medicine | Vanderbilt University | Vanderbilt Medical Center

Evolution and Phylogenetics

DNA sequences contain the genetic footprints of the past and can help scientists retrace the evolution of Life, using phylogenetics and evolutionary analyses. We are investigating the evolutionary history of the Wolbachia clade to determine the host range limits of this widespread endosymbiont, the novel genetic lineages in this important bacteria, and the direction of evolution of endosymbiotic associations, including parasitism and mutualism. During its radiation, Wolbachia evolved a set of labile interactions that span the spectrum of microbe-host associations from strict mutualism in filarial nematodes to reproductive parasitism in arthropods. Their intricate parasitic effects on arthropod reproduction are collectively denoted 'reproductive parasitism', and their beneficial effects in filariid nematodes include vital impacts on fertility and larval viability. We use this unique, natural plasticity along with high throughput molecular approaches to distinguish the evolutionary events that shape lifestyles among these endosymbionts and which of these events come first. These analyses will contribute to a fuller understanding of what makes some endosymbionts evolve into organelles and others into long-term intracellular parasites.


Unrooted phylogenetic tree of the Wolbahcia clade showing our current knowledge of the genetic lineages, host range, and evolutionary relatiosnhips of Wolbachia. Wolbachia are one of the most widespread and dynamic, obligate bacterial endosymbionts on the planet.