Vertically-transmitted fungal symbiont effects on rare and common grasses
What makes some species common while others rare? This is a huge question with many answers, but a potential driver of species abundance that remains understudied is the interaction between host species and their microbial symbionts. Beneficial symbionts could promote the dominance of common host species by increasing their population growth rates more than they do for rare species, and symbiont benefits could be important for maintaining rare species in communities. Alternatively, intrinsic differences in demography, independent of interactions with symbionts, could be the main driver of species’ relative abundances. In this study, we used demographic modelling with five years of data from experimental host populations to compare how symbiotic fungal endophytes, which are vertically transmitted from parent plant to offspring, influenced the population dynamics of one pair of co-occurring, congeneric rare versus common host grasses (genus Poa). Spoiler alert: Fungal symbionts maintain a rare plant population but demographic advantage drives the dominance of a common host!
Collaborators: Jennifer Rudgers and Tom Miller.
Effects of an invasive rose on native plant-pollinator interactions
Biological invasions can strongly influence species interactions such as pollination, and there is evidence for this especially when comparing single pairs of native and exotic, and highly invasive, plants. We know little, however, about how exotic plants alter interactions in entire communities of plants and pollinators, especially at low to medium invader densities. As a part of my undergraduate honors thesis, I experimentally removed the flowers of a showy invasive shrub, Rosa multiflora, and evaluated its effects on the frequency, richness, and composition of bee visitors to co-flowering native plants in 50mx20m plots. We found that while R. multiflora increased plot-level richness of bee visitors to co-flowering native plant species at some sites, its presence had no significant effects on bee visitation rate, visitor richness, bee community composition, or abundance overall. In addition, we found that compared to co-flowering natives, R. multiflora was a generalist plant that primarily received visits from generalist bee species shared with native plant species. Our results suggest that exotic plants such as R. multiflora may facilitate native plant pollination in a community context by attracting a more diverse assemblage of pollinators, but have limited and idiosyncratic effects on the resident plant-pollinator network in general. Read more here.
Collaborators: Tiffany Knight and Laura Burkle.