About

Our faculty are engaged and dedicated educators, advisors, and mentors and have been honored with numerous university-wide and national teaching awards. Our classes emphasize the latest research coupled with cutting-edge technology and practices making our graduates among the most competitive candidates in the country for natural resource professions. Our curricula include everything from protected lands management and urban forestry, to industrial forestry operations and ecology. Small class sizes and faculty dedicated to teaching afford FREC students the chance to get to know their professors personally. Wide varieties of academic and professional opportunities are available through research, student organizations, and public outreach programs organized by the faculty.

Research topics

• Botany
• Biology
• Genetics
• Evolutionary biology
• Ecology
• Demography
• Computational biology

Selected publications

• Phenotypic plasticity evolved for climate variability constrains performance under climate warming

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-03-20 · 1 citations

  articleOpen access

  Abstract Phenotypic plasticity allows plants to rapidly respond to changing environments without the need for evolutionary change or migration. While selection can create variation in plasticity across natural populations, these responses are not adaptive in all environments. To predict whether plasticity will be adaptive requires evaluation of its fitness effects across a range of environments, including novel ones. Here, we test how traits and their plasticity vary for genotypes collected across a natural hybrid zone between two tree species with contrasting climatic niches. Fast-growing Populus trichocarpa inhabits maritime environments with relatively warm and stable temperatures, while P. balsamifera inhabits continental environments with cold winters and large temperature variance throughout the year. We planted 44 clonally replicated genotypes into thirteen common gardens and measured vegetative phenology, leaf morphology, stomata morphology and conductance, and photochemistry. Overall, genotypes from colder, more continental environments exhibited higher plasticity. P. balsamifera ancestry was associated with increased plasticity in timing of fall phenology, stomatal conductance, and leaf mass per unit area. We assessed the effects of trait plasticity on fitness estimated as yearly growth across common gardens and found that the plasticity-fitness relationship was often garden-specific, indicating that the planting environment did not consistently mediate plasticity-fitness relationships. When the effects of trait plasticity on growth varied by garden temperature, higher plasticity generally had neutral or negative associations with growth in warmer environments. These results suggest that elevated plasticity evolved in a P. balsamifera genomic background as part of a climate generalist strategy to seasonal temperature variability, but that there is a trade-off between plasticity and growth in warmer environments. Consequently, less-plastic but warm-adapted P. trichocarpa genotypes are likely to have a fitness advantage under warming climates. These results demonstrate that plasticity may sometimes be maladaptive and will not be universally beneficial in a warming world.

  PublisherOA PDFDOI

• Author response for "The role of cytonuclear interactions to plant adaptation across a Populus hybrid zone"

  2025-08-13

  peer-review
  PublisherDOI

• The role of cytonuclear interactions to plant adaptation across a <i>Populus</i> hybrid zone

  Proceedings of the Royal Society B Biological Sciences · 2025-11-01 · 2 citations

  articleOpen access

  Co-adaptation of cytoplasmic and nuclear genomes is critical to physiological function for many species. Despite this understanding, hybridization can disrupt co-adaptation, leading to a mismatch between maternally inherited cytoplasmic genomes and biparentally inherited nuclear genomes. Few studies have examined the consequences of cytonuclear interactions to physiological function across environments. Here, we quantify the degree of co-introgression between chloroplast and nuclear–chloroplast (N-cp) genes across repeated hybrid zones and its consequences to physiological function across environments. We use whole-genome resequencing and common garden experiments with clonally replicated genotypes sampled across the natural hybrid zone between Populus trichocarpa and P. balsamifera . Geographic clines were used to test for co-introgression of the chloroplast genome with N-cp and non-interacting nuclear genes. Co-introgression of the chloroplast alongside N-cp genes was limited, although contact-zone specific patterns point to the importance of regional differences. Combining ancestry estimates with phenotypic data across common gardens revealed that mismatches between chloroplast and nuclear ancestry can influence physiological performance, but the strength and direction of these effects vary depending on the environment. Overall, this study highlights the importance of cytonuclear interactions to adaptation, and the context-dependent role the environment may play influencing that interaction.

  PublisherDOI

• Climate and hybridization shape stomatal trait evolution in <i>Populus</i>

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-07-25

  preprintOpen access

  Abstract Stomata play a critical role in regulating plant responses to climate. Where sister species differ in stomatal traits, interspecific gene flow can influence the evolutionary trajectory of trait variation, with consequences to adaptation. Leveraging six latitudinally-distributed transects spanning the natural hybrid zone between Populus trichocarpa–P. balsamifera , we used whole genome resequencing and replicate common garden experiments to test the role that interspecific gene flow and selection play to stomatal trait evolution. While species-specific differences in the distribution of stomata persist between P. balsamifera and P. trichocarpa , hybrids on average resembled P. trichocarpa . Admixture mapping identified several candidate genes associated with stomatal trait variation in hybrids including TWIST , a homolog of SPEECHLESS in Arabidopsis , that initiates stomatal development via asymmetric cell divisions. Geographic clines revealed candidate genes deviating from genome-wide average patterns of introgression, suggesting restricted gene flow and the maintenance of adaptive differences. Climate associations, particularly with precipitation, indicated selection shapes local ancestry at candidate genes across transects. These results highlight the role of climate in shaping stomatal trait evolution in Populus and demonstrate how interspecific gene flow creates novel genetic combinations that may enhance adaptive potential in changing environments.

  PublisherOA PDFDOI

• Climate and hybridization shape stomatal trait evolution in <i>Populus</i>

  New Phytologist · 2025-11-17 · 1 citations

  articleOpen access

  Stomata play a critical role in regulating plant responses to climate. Where sister species differ in stomatal traits, interspecific gene flow can influence the evolutionary trajectory of trait variation, with consequences for adaptation. Leveraging six latitudinally distributed contact zones spanning the natural hybrid zone between Populus trichocarpa × Populus balsamifera, we used whole genome resequencing and replicate common garden experiments to test the role that interspecific gene flow and selection play in stomatal trait evolution. While species-specific differences in the distribution of stomata persist between P. balsamifera and P. trichocarpa, hybrids on average resemble P. trichocarpa. Admixture mapping identified several candidate genes associated with stomatal trait variation in hybrids, including TWIST, a homolog of SPEECHLESS in Arabidopsis, which initiates stomatal development via asymmetric cell divisions. Geographic clines revealed candidate genes deviating from genome-wide average patterns of introgression, suggesting restricted gene flow and the maintenance of adaptive differences. Climate associations, particularly with precipitation, indicated selection shapes local ancestry at candidate genes across contact zones. These results highlight the role of climate in shaping stomatal trait evolution in Populus and demonstrate how interspecific gene flow creates novel genetic combinations that may enhance adaptive potential in changing environments.

  PublisherOA PDFDOI

• Variation in responses to temperature in admixed <i>Populus</i> genotypes predicts geographic shifts in regions where hybrids are favored

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-05-22 · 2 citations

  preprintOpen access

  Summary Plastic responses of plants to their environment vary as a result of genetic differentiation within and among species. To accurately predict rangewide responses to climate change, it is necessary to characterize genotype-specific reaction norms across the continuum of historic and future climate conditions comprising a species’ range. The North American hybrid zone of Populus trichocarpa and P. balsamifera represents a natural system that has been shaped by climate, geography, and introgression. We leverage a dataset containing 45 clonal genotypes from this natural hybrid zone, planted across 17 replicated common garden experiments spanning a broad climatic range. Growth and mortality were measured over two years, enabling us to model reaction norms for each genotype across these tested environments. Species ancestry and intraspecific genomic variation significantly influenced growth across environments, with genotypic variation in reaction norms reflecting a trade-off between cold tolerance and growth. Using modeled reaction norms for each genotype, we predicted that genotypes with more P. trichocarpa ancestry may gain an advantage under warmer climates. Spatial shifts of the hybrid zone could facilitate the spread of beneficial alleles into novel climates. These results highlight that genotypic variation in responses to temperature will have landscape-level effects.

  PublisherOA PDFDOI

• Author response for "The role of cytonuclear interactions to plant adaptation across a Populus hybrid zone"

  2025-09-23

  peer-review
  PublisherDOI

• The role of cytonuclear interactions to plant adaptation across a <i>Populus</i> hybrid zone

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-05-15 · 4 citations

  preprintOpen access

  Abstract Co-adaptation of cytoplasmic and nuclear genomes are critical to physiological function for many species. Despite this understanding, hybridization can disrupt co-adaptation leading to a mismatch between maternally-inherited cytoplasmic genomes and biparentally inherited nuclear genomes. Few studies have examined the consequences of cytonuclear interactions to physiological function across environments. Here, we quantify the degree of co-introgression between chloroplast and nuclear-chloroplast (N-cp) genes across repeated hybrid zones and its consequences to physiological function across environments. We use whole-genome resequencing and common garden experiments with clonally replicated genotypes sampled across the natural hybrid zone between Populus trichocarpa and P. balsamifera . We use geographic clines to test for co-introgression of the chloroplast genome with N-cp and non-interacting nuclear genes. Co-introgression of chloroplast and N-cp genes was limited although contact zone-specific patterns suggest that local environments may influence co-introgression. Combining ancestry estimates with phenotypic data across common gardens revealed that mismatches between chloroplast and nuclear ancestry can influence physiological performance, but the strength and direction of these effects vary depending on the environment. Overall, this study highlights the importance of cytonuclear interactions to adaptation, and the role of environment in modifying the effect of those interactions.

  PublisherOA PDFDOI

• Improving American chestnut resistance to two invasive pathogens through genome-enabled breeding

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-02-01 · 2 citations

  preprintOpen access

  Over a century after two introduced pathogens decimated American chestnut populations, breeding programs continue to incorporate resistance from Chinese chestnut to recover self-sustaining populations. Due to complex genetics of chestnut blight resistance, it is challenging to obtain trees with sufficient resistance and competitive growth. We developed high quality reference genomes for Chinese and American chestnut and leveraged large disease phenotype and genotype datasets to develop accurate genomic selection. Inoculation and simulation results indicate that resistance may be substantially increased in trees that inherited 70% to 100% of their genome from American chestnut. To facilitate gene editing, we integrated multiple lines of evidence to discover candidate alleles for blight resistance and susceptibility. These genomic resources provide a strong foundation to accelerate restoration of this iconic tree.

  PublisherDOI

• Evaluating restoration candidates: Performance of blight-tolerant American chestnut varieties in open field and shelterwood silvicultural conditions

  Forest Ecology and Management · 2025-11-01 · 1 citations

  article
  PublisherDOI

Recent grants

• CAREER: Integrating Whole-Genome Association Mapping and Landscape Genomics to Understand Climatic Adaptation in Populus

  NSF · $1.6M · 2011–2017

• RESEARCH-PGR: Genomic architecture of porous species boundaries: implications for climatic adaptation and hybrid breeding

  NSF · $2.5M · 2019–2025

Frequent coauthors

• Haktan Suren

  Thermo Fisher Scientific (United States)

  60 shared

• Oliver Fiehn

  University of California, Davis

  53 shared

• David B. Neale

  Southcentral Foundation

  53 shared

• Fernando Guerra

  University of Talca

  53 shared

• Mark F. Davis

  Indian Institute of Science Education and Research Kolkata

  52 shared

• Robert W. Sykes

  National Renewable Energy Laboratory

  52 shared

• James H. Richards

  52 shared

• Richard Shuren

  GreenWood Resources (United States)

  32 shared

Labs

• Forest Resources and Environmental Conservation Research GroupPI

Awards & honors

• NSF Plant Genome Research Program – “CAREER: Integrating who…
• USDA NIFA Climate Change Coordinated Agriculture Project – “…
• Genome Canada – “AdapTree: Assessing the adaptive portfolio…