Predicting evolutionary trajectories amid environmental fluctuations

Natural settings require populations to endure environmental fluctuations. These fluctuations, which may be more severe and/or frequent in a changing climate, can alter both ecological community assembly and evolutionary fitness. I will present experimental microbial work that addresses both of these aspects: first, how do biotic interactions between community members alter their evolutionary trajectories, and second, how do abiotically fluctuating environments steer evolutionary trajectories? We leverage high-resolution DNA-barcoding for evolutionary lineage tracking in yeast to test predictions of mathematical models. Theory predicts that ecological interactions can constrain evolutionary trajectories, causing a strain to further specialize to its niche in the presence of another strain, while generalizing to a new niche in the absence of the second strain. We are testing this prediction by evolving pairs of yeast strains that coexist in subdivided environments containing two niches. On the topic of evolution in abiotically fluctuating environments, theory predicts that fluctuating between correlated fitness landscapes can increase adaptation in a single landscape compared to evolution in the single landscape alone. I will present preliminary confirmation of this prediction, as well as continuing experiments probing this question.