Evolutionary and ecological genetics of Wolbachia and their Drosophila hosts
We are a collaborative team of researchers studying Drosophila-Wolbachia interactions the evolution of reproductive isolation in many systems. Our current projects combine approaches from genomics, genetics, cell biology, and population biology to better understand Wolbachia effects on host physiology and fitness that underlie Wolbachia spread. This knowledge is crucial to improve the efficacy of Wolbachia from Drosophila as a biocontrol of vector-borne disease (particularly dengue and now Zika). Our field work takes us from local orchards to sites overseas where we sample Wolbachia-infected flies from Africa, Asia, Australia and South America. We are fortunate to conduct our lab research at the University of Montana in beautiful Missoula, Montana.
Evolutionary genomics of host-Wolbachia interactions
Several projects are assessing the genetic basis of Wolbachia effects on host physiology and fitness that underlie Wolbachia spread. For example, we have demonstrated that interactions between hosts and their Wolbachia affect the strength of cytoplasmic incompatibility (CI); CI reduces the egg hatch of uninfected females mated with Wolbachia-infected males. Analysis of many whole Wolbachia genomes has found support of the theoretical prediction that selection does not act to increase or maintain CI, with evidence that non-CI causing strains often have remnants of CI loci in their genomes. Very recent results have also revealed that insertion sequence elements in WO phage regions mediate horizontal transfer of CI-causing operons between divergent Wolbachia (see below). Together, our projects are increasing our understanding of the evolutionary genetic basis of phenotypes underlying spread of Wolbachia within and between host species.
Local adaptation and reproductive isolation
Our group is also interested in understanding local adaptation within, and the evolution of reproductive isolation between, host species. In the past this research has involved assessing the cell basis of temperature adaptation in natural and experimentally evolved Drosophila populations. More recently, we've described a new D. yakuba-D. teissieri hybrid zone, in collaboration with Daniel Matute's group. Because Wolbachia are maternally transmitted endosymbionts, hybridization and introgression can lead to between species Wolbachia spread. In this way (and others), our work on local adaptation and reproductive isolation overlaps nicely with our work focused on within and between host Wolbachia spread.
We are currently funded by the National Institutes of Health (NIH) to determine the effects of Wolbachia on host physiology and fitness that enable Wolbachia spread. We are grateful for this funding and for past funding from the NIH, the National Science Foundation, and several other agencies.