Utilizing genotype-phenotype association studies and landscape genomics, Dr. Holliday elucidates the genetic determinants of complex adaptive traits, using the black cottonwood tree (commonly known as ‘poplar’) as a model.
Forest tree populations are well adapted to their local environments at present, but anthropogenic climate change is substantially altering adaptive landscapes, particularly in temperate and boreal regions. In the absence of adaptation to rapid changes in climatic, tree populations will be forced to either migrate or be extirpated. As it is unlikely that migration rates will be sufficient to realize the range shifts predicted by climate-based species distribution models, the importance of adaptive evolution cannot be underestimated. In order to predict the potential for adaptation in the context of climate change, one must first have an understanding of the genomic underpinnings of the relevant traits.
The overarching goal of Dr. Holliday’s research is to elucidate the genetic determinants of complex adaptive traits using genotype-phenotype association studies and landscape genomics. To do this, he employs 'next gen' sequencing of large, diverse tree populations, which are grown in common environments and measured for a variety of adaptive traits, including timing of growth and dormancy transitions, tolerance to temperature extremes and drought hardiness. He is currently applying this approach to the model tree black cottonwood (aka 'poplar'), as well as several economically and ecologically important conifers such as spruce and pine. A better understanding of the genomic underpinnings of complex adaptive traits facilitates predictions of carbon sequestration in future forests, enhances the adaptive potential of local populations through conservation of ecologically-relevant genetic variation, and facilitates sustainable production of wood biomass through genome-enabled breeding. More generally, these studies begin to provide answers to long-standing questions in evolutionary ecology about the genetic architecture of adaptation.