Research

All photos by A. Keeler. Top to bottom: L. argenteus & B. flavifrons; L. leucanthus; V. americana.
I'm interested in learning how drought will alter legume-rhizobia mutualisms and their associated ecosystem services. It is important to determine 1) when rhizobia are dormant (ecological scale) and 2) how the mutualism may break down due to long-term climate stress (evolutionary scale) as these processes may impact the legume host and the local environment.
The Rocky Mountain Biological Laboratory (RMBL, photo to the right) offers an excellent system to answer questions about phenology and drought. At RMBL, total June precipitation has decreased significantly since the 1980s, and the date of spring snowmelt has shifted earlier, extending the summer drought period. Lupinus argentues, Lathyrus lanszwertii var. leucanthus, and Vicia americana, three biologically important, rhizobia-hosting leguminous species found at RMBL are the focal species for this experiment (photos to the left). Dry soils may not contain active rhizobia at the time of Lupinus, Lathyrus, and Vicia germination or early growth which could impact germination success and phenology.
Q1. How will rhizobial phenology (i.e., changes in metabolic state) shift in drought conditions? Preliminary results suggest that the onset of germination of L. leucanthus and V. americana in soils depleted of rhizobia is significantly delayed by two weeks compared to germination in natural soils and that legume germination success is halved when completely mismatched from rhizobial partners (unpublished data). The timing of plant germination is particularly important as it relates to seedling survival, downstream phenological patterns, and reproductive success.
Q2. How will prolonged drought impact legume-rhizobia mutualisms? The ‘symbiosis island’ is a segment of the symbiotic rhizobium genome. Over rapid evolutionary time, rhizobia in extreme environments have lost this segment of their genome due to natural selection; the maintenance of symbiotic function is costly to the bacteria in harsh environments. The loss of this segment of DNA leads to the inability to nodulate in host legume roots and ultimately causes a complete breakdown of the mutualism. L. argenteus and associated rhizobia are the focal species of this ongoing common garden project.
All of my work is done at the Rocky Mountain Biological Laboratory in Gothic, Colorado and at the University of California, Riverside.
All photos by A. Keeler. Top to bottom: a field site on Mt. Baldy with L. argenteus flowers; L. leucanthus seeds; the RMBL field station.
Photos from top to bottom: Toronto the Blue Jay from the Steven's Lab; sampling water from an urban day-lighted stream in Minneapolis in the winter for the Finlay Lab; sampling water from the Mississippi river in downtown Minneapolis for the Finlay Lab. All photos by A. Keeler
Previous research experience
2017 Junior Specialist, University of California, Riverside (EEOB)Manage common garden projects on seed germination and functional trait expression of six species collected from three distinct elevations at the Rocky Mountain Biological Lab, CO; manage undergraduate volunteers; conduct fieldwork at the Rocky Mountain Biological Lab. Advisor: Dr. Nicole Rafferty
2014 - 2015 Research Assistant, University of Minnesota, Twin Cities (EEB)Conduct research on urban and agriculturally influenced aquatic biogeochemistry and ecology; stable isotope mapping of food webs. Senior thesis: The effects of management regimes on nitrate assimilation in urban daylighted streams.Advisor: Dr. Jacques Finlay
2015 - 2016 Research Volunteer, University of Minnesota, Twin Cities (EEB)Assist with behavioral research on blue jays and starlings relating to the evolution of cognition, foraging, trade-offs, social vs. independent learning, and aposematism.Advisor: Dr. David Stephens
2013 Research Assistant, University of Minnesota, Twin Cities (Entomology)Assist with IPM research regarding plant herbivory by Western corn rootworms, Diabrotica virgifera virgifera. Advisor: Dr. Ken Ostlie



Photo below: The Finlay Lab research team sampling agriculturally influenced stream networks in Southeastern MN.