Graduate Seminar in Plant Traits, Fall 2009

Instructors: Jennifer Powers, Jeannine Cavender-Bares, Sarah Hobbie, Rebecca Montgomery, Peter Reich, Imke Schmitt, Peter Tiffin and George Weiblen

Over the past few decades, the study of plant traits has emerged as a theme that unifies plant ecology and evolution. Variation in plant functional traits within and among species reflects fundamental physiological tradeoffs, and may explain patterns of species distributions and coexistence (Figure 1). Moreover, with increasing scientific and public concern about potential effects of global environmental change, the scientific community has become very interested in using plant traits to scale from sub-cellular to individual to ecosystem-level to global biogeochemical processes.

Figure 1. One potential conceptual model outlining linkages and feedbacks among evolution and function of plant traits, and effects on community and ecosystem processes (J. Cavender-Bares, K. Kozak, P. Fine and S. Kembel, The merging of community ecology and phylogenetic biology, in review).

Course Format

The ecology and evolution of plant traits, and integrating information on the traits of individual plants into ecosystem level processes is already a focus of the research of many UMN faculty. In this 2-credit graduate seminar, we will explore plant traits through lectures, discussions, and readings.

Potential Lecture Topics

Lecture topics may include the following:

Leaf Economics Spectrum and the Global Distribution of Plant Traits
Phylogenetics and Ecophylogenetics
Ancestral Character State Reconstruction and Character Correlation
Analyses
Natural Selection and Adaptation
Phenotypic Plasticity
Aboveground Traits
Belowground Traits
Community Assembly
Ecosystem Processes
Global Change
Measuring Traits

Faculty Research Profiles

Reich Lab: Overview of general goals and Specific examples

In our lab, we seek to better understand the mechanisms that control composition, diversity, structure, and function of plant ecosystems; and especially the links between resources, composition, diversity, structure and function, all subject to a variety of natural and human disturbances. One approach we often employ involves asking whether the ecophysiological traits of individual taxa (a) make them less or more successful in specific contexts than their competitors and/or (b) change the rules of the game by influencing resource availability, micronenvironment and/or disturbance regime itself.

Some specific (and overlapping) issues and questions.

*Traits and functional scaling: Do trade-offs of specific traits have similar consequences in all terrestrial ecosystems on earth, and if so, can we predict the ecophysiological traits of species from their ecological behavior and vice-versa, thus supporting the notion of one general trait-based theory?

*Traits and ecological processes:

How do the differing ecophysiological traits of co-occurring plant species regulate their competitive interactions, success or failure in specific contexts, and hence the dynamics of patches and communities over time & space? In other words, do trait differences both build and respond to ecological niches?

*Traits and ecosystem processes:

a) Emergent scaling? Do genotypically determined leaf traits constrain and determine (ecosystem scale) canopy and root traits and thus exert major control on ecosystem scale structure and function?

b) How do traits influence soils and biogeochemical cycling (and what are consequences for plant community dynamics?)?

Tiffin Lab:

We use both population genetic and empirical approaches to investigate a variety of questions related to trait evolution. We are currently working on three main projects; the ecological and evolutionary forces of species range limits, characterizing the demographic history of Populus balsimifera and using that information to identify the genetic basis of adaptation to northern latitudes, and using association genetics and greenhouse studies to identify traits responsible for variation in mutualistic interactions, and to characterize the evolutionary forces that have acted on those traits.

In addition to these ongoing projects, I remain interested in the evolution of plant defense, and how individual traits are integrated to affect plant resistance and tolerance to herbivore and pathogen damage.

Weiblen Lab:

I am interested in the use of phylogenetic information to test hypotheses of trait evolution. Topics of interest include ancestral state reconstruction, directionality of trait change, and the application of the comparative method in testing hypotheses of adaptation. Examples of my work in this area include the studies of plant breeding system evolution, plant-insect coevolution, and the host specificity of insect herbivores.

Phylogenetic dispersion of host range in thirty herbivore species from a New Guinea plant community sample (black = feeding; white = not feeding). Herbivores are grouped into non-significantly clustered species including polyphagous generalists, and significantly clustered species including oligophagous specialists feeding on Macaranga, Ficus, or Psychotria. Branch lengths of the host plant community phylogeny are proportional to molecular divergence.

Cavender-Bares Lab:

The unifying goal of my work is to understand how functional traits of plants link evolutionary history to current ecological processes with consequences for ecosystem function and stability on an increasingly human dominated planet. Given Darwins insight that close relatives should be highly competitive due to their similarity, I have sought to determine mechanisms that explain the coexistence of closely related species in oak dominated forests of the southeastern U.S. and to learn what traits can tell us about the critical processes involved in the assembly of communities. I am currently investigating the functional mechanisms underlying local adaptation in broadly distributed species.