Effects of rapid evolution on alternative community states

Species interactions can often allow for multiple different discrete states, or alternative community states, into which a given community can assemble. Which state is realized depends on initial conditions, and this role of history makes predicting community outcomes notoriously difficult. Feedbacks across spatial scales coupled with coevolution within communities further complicates matters. I will use the well-described study system of microbes in Diplacus aurantiacus nectar to study how rapid evolution alters alternative community states at both single-community and metacommunity scales.

Maintenance of variation for ongoing eco-evo dynamics

Feedbacks between evolutionary and ecological processes that occur because they operate on similar timescales is called eco-evo dynamics. For eco-evo dynamics to persist, the variation underlying both processes must be maintained, yet this fundamental component of eco-evo dynamics has received little attention. Pea aphids can evolve resistance to parasitoid wasps rapidly enough to affect the host–parasitoid dynamics. Through long-term lab experiments and simulations, we show that aphids dispersing among patches that vary in parasitoid abundance can produce both the ecological stability and balancing selection necessary for ongoing eco-evo dynamics.

Effects of population fluctuations on genome evolution in the wild

How do extreme population fluctuations structure genomes in wild populations? I’m exploring this question with a population of midges in Lake Mývatn, Iceland, where they have irregular population fluctuations of about 5 orders of magnitude. As part of a long-term monitoring project at Mývatn, Dr. Árni Einarsson has estimated midge densities, and collected and stored midge samples since 1977. I am leveraging this time series of whole-genome and ecological data to assess how genomic structure is affected by these extreme population dynamics.

Trait coevolution among competitors and coexistence

Coevolution among competitors can result in traits that promote niche partitioning and coexistence or traits that promote greater conflict and competitive exclusion. We used an eco-evolutionary model where competitors “invest” in coexistence- and exclusion-promoting traits to assess when trait coevolution should promote coexistence or exclusion. We found that communities should often contain both types of traits, but exclusion-promoting traits should more strongly influence trait coevolution community-wide. We also found that, despite being more influential, species invested relatively more in exclusion-promoting traits should be most vulnerable to exclusion by a new invader. This may make communities containing multiple species with exclusion-promoting traits evolutionary transitory.