Evolutionary Ecology

My training as a PhD student was firmly footed in the sort of MacArthurian ecology that focuses at the population and individual scale to ask questions about the selective forces that shape traits and life histories. Demographic data and analyses, as well as comparative analyses (i.e., mapping traits on a phylogeny), were important tools that I used to study bet hedging, life history evolution, and breeding system evolution in a clade of evening primroses (Oenothera) that has diversified across the landscape of western North America (photo by Rob Raguso).

Bet Hedging - Bet-hedging traits are interesting because they seem to be maladaptive: mean fitness (i.e., fitness if the organism were to constantly experience the average environment) is sacrificed in favor of reduced variance in fitness, because this leads to higher long-term fitness. I showed that seed banking has these effects, using demographic data collected from natural populations of two desert evening primroses (Oenothera). I also considered the consequences of seed banking for genetic diversity, the dynamics of allele frequencies, traits, population persistence, and species coexistence in a paper published in the Quarterly Review of Biology. My time spent thinking about bet hedging still influences me, in terms of how temporal and spatial heterogeneity shape species, and how species’ responses to heterogeneity in turn influence their persistence and coexistence in communities.

Life History Evolution - Why reproduce once vs. more than once per lifetime? It’s a fundamental question of life history theory (Cole’s Paradox). Using a comparative analysis of life history varation, I found support for the notion that the annual life history (monocarpy, also known as semelparity) evolves where adult survival is low and juvenile survival high.

Breeding System Evolution - Stebbins (1950) predicted that the evolution of selfing should be associated with climatic extremes, but this pattern had not been documented. With Kent Holsinger, Kathyrn Theiss, and Michael Donoghue, I found self-compatibility to be associated with the coldest and mildest winter temperatures, as well as the strongest and weakest drought, experienced by species in a clade of evening primroses (Oenothera).