Xiao-Ru Wang inspecting a pine tree

The ability of a species to sustain environmental change is primarily determined by its genetic reservoir, which is shaped over the course of history through demography and selection. We apply ecological and genomics tools to understand the origin and distribution of genetic diversity across landscapes in Eurasian conifer species. We use seed orchards as a study system to evaluate the impact of abiotic and biotic factors and management practices on genetic diversity and breeding gain in seed crops, and the adaptability of the regenerated production forests to future climate.

Ecological genomics

Local adaptation in which local genotypes have a fitness advantage than foreign genotypes is well known among long-lived tree species. Rapid climate change can break this genetic-environmental association much faster than trees’ ability to evolve in situ or migrate, thus creating a mismatch between genetic adaptation to altered environmental conditions. Inferences of genotype-environment associations due to polygenic nature of adaptive traits and the complexity of adaptive and dispersal-demographic factors that contribute to genetic differentiation across species range. Using landscape genomics approaches, we interrogate genome-wide variation across landscapes for understanding the extent to which evolutionary forces, e.g. demographic events, gene flow, introgression and selection, shape past and contemporary populations’ genetic structure, and identify those populations that may be most at risk under climate change. This research is conducted for major conifer species in Eurasia, e.g. Pinus sylvestris, Pinus tabuliformis, Pinus yunnanensis, Pinus densata and Picea abies.

Collage of four images showing a tree top on the left upper corner, a section of a map of China coloured in different colours and colour intensities on the top right corner, a coloured map of Scandinavia and upper Europe with dark blue colour in the North that gradiently goes over to magenta end to yellow in the South on the bottom left corner and horticultural tunnels with pine trees on the bottom right.A) Pinus densata on the Tibetan Plateau; B) Spatial structure of genomic diversity in P. densata; C) Hardiness variation in Scots pine; D) Controlled mating experiment in a Scots pine seed orchard

Seed orchards and adaptability of production forests

Efficient use of breeding resources requires a good understanding of the genetic composition of the founder materials for predicting the gain and diversity in future generations. For conifer trees, seed orchard is the link between tree breeding and the production forest. Well-functioning seed orchard is the most cost efficient and realistic way to increase timber production from forestland during the coming century. Our research in this area focuses on: 1) the assessment of diversity and coancestry in breeding populations of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies); 2) the mating system in seed orchards of the two species, and pedigree structure and diversity in seed crops; and 3) the adaptation of orchard crops to different climate zones and thus formulating site-specific seedlot selection system for reforestation. These activities are in close collaboration with Skogforsk.

Read more about Xiao-Ru Wang's research on the homepage of Umeå University

Key publications

  • Hall, D., Olsson, J., Zhao, W., Kroon, J., Wennström, U., Wang, X-R. 2021. Divergent patterns between phenotypic and genetic variation in Scots pine. Plant Communications,2:100139.
  • Zhao, W., Sun, Y-Q., Pan, J., Sullivan, A., Arnold, M.L., Mao, J-F., Wang, X-R. 2020. Effects of landscapes and range expansion on population structure and local adaptation. New Phytologist. 228: 330-343.
  • Sullivan, A.R., Schiffthaler, B., Thompson, S.L., Street, N.R., Wang, X-R. 2017. Interspecific plastome recombination reflects ancient reticulate evolution in Picea (Pinaceae). Molecular Biology and Evolution 34:1689-1701.
  • Funda, T., Wennström, U., Almqvist, C., Andersson Gull, B., Wang, X-R. 2016. Mating dynamics of Scots pine in isolation tents. Tree Genetics & Genomes 12:112.
  • Wang, B., Mao, J-F., Gao, J. Zhao, W., Wang, X-R. 2011. Colonization of the Tibetan Plateau by the homoploid hybrid pine Pinus densata. Molecular Ecology 20: 3796-3811.