Thomas G. Whitham

Regents’ Professor

Phone: 928-523-7215
Office: Bldg. 21 room 408

More information:

Research/teaching interests

  • population and community ecology
  • ecological genetics

Academic highlights

My research is focused on cottonwood riparian communities and pinyon-juniper woodlands.  These studies emphasize plant-herbivore interactions and a community-level understanding of the consequences of plant genetics and environmental stress on keystone species. 

These studies include:

  1. plant-fungal and ant-aphid mutualisms
  2. interactions among keystone species such as beavers and beetles which affect the arthropod community
  3. ecological, evolutionary and conservation implications of plant hybridization
  4. the genetics of community structure and biodiversity
  5. the role of plant ontogeny in affecting herbivore population dynamics and keystone species
  6. the ecosystem consequences of genetic variation in plant resistance to herbivory, and
  7. the role of environmental stress in affecting dominant plants and pest outbreaks

These studies have been very collaborative and are based upon the combined efforts of many colleagues and students.

My teaching is focused on plant ecology and field ecology in which students work on original field problems of their choosing.  Field ecology emphasizes the discovery of original problems, devising appropriate sampling methods, data collection, statistical analyses, oral presentations in national meeting format and written presentation in journal format. 

The skill of seeing or discovering an original problem is the most difficult and the most important to emphasize.  This approach is very concept oriented and helps students see the great problems that surround us but which we are often unaware.

This faculty member is also a mentor in the NSF IGERT graduate training program: NAU’s IGERT PhD program seeks to identify key links between genes and the environment and is designed to train exceptional graduate students in molecular genetics, environmental sciences, and spatio-temporal modeling.

A genes-to-ecosystem approach is a major emphasis of my collaborative research efforts that have focused on threatened riparian communities and pinyon woodlands in the western US, and eucalypt forests in Tasmania, Australia. 

Our studies are funded by a National Science Foundation Frontiers in Integrative Biological Research (FIBR) grant, which focuses on the development of the emerging field of community and ecosystem genetics, a Bureau of Reclamation grant that emphasizes a genetics approach in riparian habitat restoration, a National Science Foundation grant that emphasizes the community consequences of climate change in pinyon-juniper woodlands, and an Australian Research Council grant to study how genetic variation in eucalypts affects their dependent arthropod communities. 

These combined studies focus on a genes-to-ecosystem approach to understand the genetic components of community structure and biodiversity, community heritability and evolution, and the ecological and evolutionary consequences of climate change. 

Specific studies/issues include: 

  1. how different plant genotypes support different arthropod and microbial communities, which in turn has a major impact on biodiversity
  2. how key mutualisms such as plant-fungal and ant-aphid interactions are influenced by the genetics of their host plants
  3. the quantitative genetics of interactions among keystone species such as beavers and beetles, which in turn determine the composition of the arthropod community
  4. the ecological, evolutionary and conservation implications of plant hybridization
  5. the role of plant ontogeny in affecting plant chemical defenses and their interactions with keystone herbivores
  6. the quantitative genetics of ecosystem processes such as decomposition, nitrogen mineralization and ecosystem productivity
  7. the role of environmental stress in affecting foundation plant species, pest outbreaks and community structure
  8. how climate change can be an agent of natural selection on foundation plant species, which then shifts the structure of the dependent community

In studying these basic issues we are working with the Bureau of Reclamation, the Ogden Nature Center and the Utah Department of Natural Resources to establish long-term and large-scale scientific experiments that address fundamental issues of both basic and applied value. 

For example, because all the trees in these plantings are clones of known genetic composition and/or pedigree we can quantify community heritability and quantify how genetic diversity in a foundation tree species affects the biodiversity of the community it supports. 

Understanding the genetic components of community structure and biodiversity are also important for decision makers who want to restore habitats and maximize biodiversity. 

Furthermore, in the process of setting up these experiments we also restore an important riparian habitat that is now listed as threatened in the arid southwestern United States.  These studies are based upon the combined efforts of many colleagues and students. 

A key paper that illustrates the collaborative nature of our approach is: Whitham, T.G, J.K. Bailey, J.A. Schweitzer, S.M. Shuster, R.K. Bangert, C.J. LeRoy, E. Lonsdorf, G.J. Allan, S.P. DiFazio, B.M. Potts, D.G. Fischer, C.A. Gehring, R.L. Lindroth, J. Marks, S.C. Hart, G.M. Wimp, and S.C. Wooley.  2006. 

A framework for community and ecosystem genetics:  From genes to ecosystems.  Nature Reviews Genetics 7:510-523.  We have a very interactive group and more information about our research efforts can be obtained at our websites: