Research in the lab focuses on the population-level, ecological, and evolutionary responses of plants to environmental disturbance and variation. Core interests include species responses to climate change, speciation in diverse plant lineages, and on the causes and consequences of wildfire.
Dimensions of Biodiversity in South African Proteas and Pelargoniums. In collaboration with Justin Borevitz at Australian National University and Carl Schlichting and others at the University of Connecticut, we are exploring the relationship between functional trait evolution, functional genetic variation, and local adaptation and speciation in two highly diverse lineages: genus Protea (Proteaceae) and genus Pelargonium (Geraniaceae) in the Cape Region of South Africa. We are combining field surveys and common garden experiments with next-generation sequencing of SNPs and transcriptomes to discover the functional variation associated with speciation and local adaptation in these groups. We are also relating functional variation at the species level to community level ecosystem function, including resilence to drought and wildfire. Supported by NSF 1045985.
|Thinning of Sierra forests as a natural experiment to test the effects of density and fire severity on forest dynamics. Federal agencies have recently treated (by thinning and/or prescribed fire) millions of hectares of publicly owned forest land to reduce fuel loads with the goal of moderating fire behavior. These management methods have been proposed in California as a way of supplying potentially sustainable biomass energy while improving long-term carbon storage in forests. But what are the effects of these treatments on forest dynamics and plant communities, with and without subsequent wildfire? In collaboration with Hugh Safford of the U.S. Forest Service, we are sampling thinned and adjacent unthinned areas in 12 fires across National Forests in California to explore effects of forest structure, weather and topography on fire effects and plant community reponses. Supported by funding from USFS and the California Energy Commission.
|Evolutionary ecology of colonizing species. Species in genus Erodium (Geraniaceae) have naturalized in both California and Chile and have remarkably wide distributions ranging from deserts to wet coastal areas and mountain foothills. What allows relatively recent colonizers like these to attaing such broad ecological ranges? Using field and greenhouse experiments, we are identifying the sources of phenotypic and demographic variation in naturalized exotic species of Erodium in populations in California and Chile. In collaboration with Brooke Jacobs and Ernesto Gianoli, we have surveyed 20 populations from each continent to compare patterns of spread, population performance, and phenotypic plasticity and local adaptation.
We have grown these in common garden experiments in Davis to assess the roles of plasticity and local adaptation in these replicate invasions. With Tina Heger we are also comparing to populations in the native range in Europe and developing molecular markers.
Supported by NSF (postdoctoral fellowship to Jacobs) and UC Davis Department of Plant Sciences.
|Bayesian hierarchical spatial models for species distributions and abundance. In collaboration with Alan Gelfand’s lab, we have used conditional modeling to take into account land use and sampling bias and resolve a truer picture of the environmental tolerances of plant species. We use these methods to test alternative causes of abundance patterns within species distributions, and variation in relative abundance within biomes. We aim to predict more robustly how climate and land use change will jointly affect species and communities. An R package for these models is in development by Ghislain Vielledent.|