University of Michigan
Department of Ecology and Evolutionary Biology

Jill Anderson, Postdoctoral Research Associate, Department of Biology, Duke University

Abstract:

All organisms must time their life history transitions very precisely to capitalize on favorable conditions. Plants initiate flowering in response to a number of reliable environmental cues. We know a great deal about the genes that promote flowering in model and agronomic species under controlled laboratory conditions; however, the genetic architecture of this ecologically-relevant trait is poorly understood in natural populations of non-model organisms. Boechera stricta (Brassicaceae), a close relative of Arabidopsis,occurs in undisturbed natural populations throughout the western United States. My collaborators and I conducted complementary field and growth chamber experiments with B. stricta to investigate the evolutionary ecology of flowering time, and ultimately dissect the genetic basis of local adaptation. 

Genetic and environmental factors strongly influenced the timing of reproduction in our field and growth chamber experiments. The timing of this transition has clear fitness consequences, as we found strong directional selection for earlier flowering in two field environments.  In the growth chamber experiment, longer winters accelerated flowering and elevated ambient temperatures delayed flowering. These results have implications for predicting B. stricta’s response to climate change. Shorter winters and higher growing season temperatures will likely alter the long-term flowering patterns of B. stricta, possibly resulting in a mismatch between floral development and optimal environmental conditions.

My analyses identified one large effect QTL, which was stable across multiple conditions in the growth chamber and field experiments. This QTL explained up to 27% of the phenotypic variance in flowering time and 45% of the variance in plant size at flowering. This nFT QTL is in the genomic region containing FT (FLOWERING LOCUS T), a key floral integrator in Arabidopsis thaliana. My recent analyses revealed fitness tradeoffs at this QTL, such that local alleles are favored in each native environment. This is one of the first demonstrations of local adaptation at the QTL-level in the plant literature. 

My future research will build on this work to explore the ability of plants to adapt to a changing climate. Anthropogenic climate change has already influenced the ecological dynamics of species, through altitudinal and latitudinal shifts in geographic ranges, altered phenology, and even local extinctions. Owing to the rapid pace of climate change, species might not have the dispersal abilities needed to track preferred environments, nor the traits necessary to survive in novel conditions. Climate change is likely to result in discordance between current trait values and optimal trait values for new conditions.  Nevertheless, the microevolutionary consequences of climate change are virtually unknown (e.g., see Anderson et al., 2011, Trends in Genetics).  How will climate change disrupt the evolutionary ecology of natural populations? At the end of the talk, I will briefly discuss my approach to this question in Boechera stricta. 

Coffee and cookies will be served at 4 p.m.

Host: Professor Lacey Knowles