Genotypes, Environments & Interactions

We often think of organisms as adapting to environmental change through migration or evolutionary adaptation. However, individual organisms can also respond to different environments within their lifespan by producing distinct phenotypes: a process known as phenotypic plasticity. Identifying environmental factors that are responsible for phenotypic change in functional traits of organisms is an important field of study, particularly in climate change.


kernel-density-estimationGaussian kernel density estimation can be used to compare the distribution of trait measurements among populations in different environments. Kernel density estimation is a nonparametric data smoothing procedure that results in probability density functions based on a finite sample data set.

S.G. Schreiber, U.G. Hacke, A. Hamann. (2015) “Variation of xylem vessel diameter in a wide-spread boreal forest tree in western Canada: insights from a large-scale reciprocal transplant experiment.Functional Ecology 29: 1392–1401.



Assisted migration is strategy by which local populations are moved from their native environment to new locations, which, under predicted climate change scenarios, may be more suitable in the future. When evaluating adaptive traits, such as the timing of leaf senescence and bud break, it is crucial to consider biologically relevant conditions into which populations are to be transplanted, such as the probability of frost.

S.G. Schreiber, C. Ding, A. Hamann, U.G. Hacke, B.R. Thomas, J.S. Brouard. (2013) “Frost hardiness vs. growth performance in trembling aspen: an experimental test of assisted migration.Journal of Applied Ecology 50: 939-949.



Numerical integration, that is, the numerical approximation of definite integrals, can help to quantify the total capacity of a trait (e.g., water transport) over a given range of an environmental condition (e.g., drought) by calculating the area under
the curve (AUC).

S.G. Schreiber, U.G. Hacke, S. Chamberland, C.W. Lowe, D. Kamelchuk, K. Bräutigam, M.M. Campbell, B.R. Thomas. (2016) “Leaf size serves as a proxy for xylem vulnerability to cavitation in plantation trees.Plant, Cell & Environment 39: 272–281.