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Dr. Jennifer Wernegreen,
Associate Scientist
Jennifer Wernegreen's CV >>
Evolution of endosymbiont lifestyles and genomesResearch
in the Wernegreen lab explores processes that shape microbial variation
and the wide array of interactions bacteria form with other species. We
focus on endosymbiotic bacteria that live within the tissues or very
cells of their hosts. By losing metabolic functions that are required
in more variable external environments, these symbionts often become
completely host-dependent. Many bacterial endosymbionts have coevolved
with insects for tens to hundreds of millions of years and provide
essential nutrients that are missing or deficient in their hosts’
diets. Other microbial associates promote their own transmission by
parasitizing the reproductive biology of numerous host species. We are
studying bacterial endosymbionts with diverse lifestyles as models to
clarify the ecological, evolutionary and genomic consequences of
intimate species associations.
Questions guiding our research include:
- How
does endosymbiosis affect bacterial genome evolution? Like genomes of
many intracellular pathogens, those of insect mutualists are
characterized by low G+C contents, accelerated evolutionary rates, and
severe genome reduction. We are attempting to untangle the contribution
of three basic evolution processes – selection, drift and mutation – to
these distinct genome features. Our projects range from inferring
fitness effects of mutations using population genetic approaches, to
reconstructing the metabolism of an endosymbiont genome that we've
sequenced here in the Bay Paul Center.
- How
do microbial associations shape the physiology and evolution of their
hosts? Using comparative genomics, we are exploring the implications of
genome variation among endosymbionts on host ecology. A new project in
the lab explores whether endosymbionts help their hosts cope with
environmental variation. We are linking changes in the gene content and
gene expression patterns of bacterial mutualists of ants to natural
environmental variation their hosts experience, including ecological
variation among ant species and extreme physiological variation among
castes in a single ant colony.
- What genome traits underlie transitions between mutualism and parasitism? In collaboration with Seth Bordenstein,
Assistant Scientist in the BPC, we are exploring lifestyle and
genome evolution in a pervasive invertebrate endosymbiont, Wolbachia.
This alpha-Proteobacterium acts as a reproductive parasite in
arthropods but as a mutualist in certain nematodes. We are exploring
the role of bacteriophage in Wolbachia genome plasticity through a
combination of molecular phylogenetics, genomics, and quantitative
assessment of phage and bacterial densities. In addition, an ongoing
project aims to identify genes responsible for distinct host effects by
comparing gene contents across diverse Wolbachia lineages.
Like many labs in the Bay Paul Center, we are delighted to pursue these and other projects as part of the new Brown-MBL joint graduate program. Interested students are welcome to contact me for more information about research opportunities.
2005 lab members (L to R): Seth
Kauppinen (Research Assistant), Seth Bordenstein (Assistant Scientist), Sarah Biber (Research Assistant), Adam Lazarus (Research
Assistant), and Jennifer Wernegreen (Associate Scientist)
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