Chris Oakley

Active Mentor - currently hosting PULSe students for laboratory rotations and recruiting PULSe students into the laboratory; serves on preliminary exam committees

Current Research Interests:

The Oakley lab is broadly interested in the ecological and evolutionary genetics of plants. One main focus of our research is the genetic basis of local adaptation. Local genotypes are often found to grow, survive, and/or reproduce better than non-local genotypes, suggesting that adaptation to one environment is costly in other environments (fitness tradeoffs across environments). Despite much empirical study, little is known about the mechanisms and genetic basis of local adaptation. Using locally adapted populations of Arabidopsis thaliana from near the northern and southern edge of the native range, we investigate the genetic basis of local adaptation, adaptive traits (e.g., freezing tolerance and flowering time), and genetic tradeoffs (fitness tradeoffs attributable to individual loci). We have developed a variety of genetic stocks that we use in field and growth chamber experiments in concert with genetic and genomic approaches.

A second main focus of our research is the consequences of genetic drift for adaptation and population persistence. A number of factors common in natural populations (e.g., a history of population bottlenecks) can increase both the chance loss of beneficial mutations and the chance fixation of deleterious mutations. Heterosis, the increased fitness in crosses between populations relative to fitness within populations, is thought to be due in part to the masking of these fixed deleterious recessive alleles in the heterozygous state. We are investigating the geographic pattern and genetic basis of heterosis in natural populations of A. thaliana to study the balance between selection and genetic drift in nature.

Selected Publications:

Ågren, J., C.G. Oakley, S. Lundemo, and D.W. Schemske. 2017. Adaptive divergence in flowering time among natural populations of Arabidopsis thaliana: QTL mapping and estimates of selection. Evolution 71:550-564.

Dittmar, E.D.*, C.G. Oakley*, J.K. Connor, B.A. Gould, and D.W. Schemske. 2016. Factors influencing the effect size distribution of adaptive substitutions. Proceedings of the Royal Society B: Biological Sciences. 283:20153065.

Oakley, C.G., J. Ågren, and D.W. Schemske. 2015. Heterosis and outbreeding depression in crosses between natural populations of Arabidopsis thaliana. Heredity 115: 73-82.

Oakley, C.G., J. Ågren, R.A. Atchison, and D.W. Schemske. 2014. QTL mapping of freezing tolerance: links to fitness and adaptive trade-offs. Molecular Ecology 23: 4304-4315.

Ågren, J., C.G. Oakley, J.K. McKay, J.T. Lovell, and D.W. Schemske. 2013. Genetic mapping of adaptation reveals fitness trade-offs in Arabidopsis thaliana. Proceedings of the National Academy of Sciences, USA 110: 21077-21082.

Oakley, C.G. and A.A. Winn. 2012. Effects of population size and isolation on heterosis, mean fitness, and inbreeding depression in a perennial plant. New Phytologist 196: 261-270.