Edward Theriot

Jane and Roland Blumberg Centennial Professor of Molecular Evolution, Section of Integrative Biology,
Director, Texas Memorial Museum

  Education | Research Interests | Activities | Publications

BIO 224A
(512) 471-4997

fax (512) 471-9651

(512) 471-5019

TMM Office:
TMM 202
(512) 232-2379
fax (512) 471-4794
Cell Phone:
(512) 736-0316


  • B.S., Zoology, Louisiana State University, Baton Rouge, 1975
  • M.S., Fisheries Biology, Botany minor, Phi Kappa Phi Honor Society, Louisiana State University, Baton Rouge, 1978
  • Ph.D., School of Natural Resources, University of Michigan, 1983

Research Interests

I study the evolution of diatoms in the context of earth history. My taxonomic focus is the diatom family Thalassiosiraceae, a family of marine and freshwater diatoms. There appears to have been a major invasion from the marine to the freshwater environment about 20 million years ago. Subsequently, these diatoms have become a major component of lake ecosystems. They have undergone periodic extinctions and radiations, apparently coinciding with glacial cycles. My most active research project is the study of speciation in the genus Stephanodiscus since the last ice age. I and colleagues are combining molecular tools with morphological studies, physiological studies and paleontological studies to examine the evolution of diatom species in the context of climate-driven limnological change. Lastly, I once took a short, regrettable foray into the systematics of a so-called dinosaur which continues to draw attention to itself.

I have a fully equipped DNA lab and share facilities with the lab of Dr. Bob Jansen. I also have outstanding light microscopic capability, full algal culturing facilities, and a well-curated personal diatom collection, especially focussing on neo- and paleo-lacustrine samples from across the USA. Students interested in diatom systematics, diatom ecology, theoretical and applied aquatic biology are encouraged to consider graduate training in my laboratory, as are students interested in using the properties of the diatom system (especially extensive fossil record, easy laboratory manipulation for experimentation) to address general questions about evolutionary and ecological principles.

Professional Activities

  • Molecular Phylogenetics and Evolution (Editorial Board 1992-2000)
  • National Science Foundation Biological Databases and Informatics Advisory Panel 2000
  • Species Concepts committee member, Systematics Agenda 2000
  • Recent Past-President of National Board of Directors, Association of Systematics Collections, 1997-1999
  • National Board of Directors, Association of Systematics Collections, 1995-1997
  • Phycological Society of America (Editorial Board 1988-1990, Associate Editor 1991-1993)


  • Conley, D.J., S.S. Kilham and E. Theriot. 1989. Variation in the silica content of diatoms: differences between marine and freshwater diatoms. Limnology and Oceanography 34: 205-213.
  • Theriot, E. 1992. Clusters, species concepts and morphological evolution of diatoms. Systematic Biology 41:141-157.
  • Theriot, E.C., S.C. Fritz and R.E. Gresswell. 1997. Long-term limnological data from the larger lakes of Yellowstone National Park. Journal of Arctic and Alpine Research 29: 304-314.
  • Theriot, E.C., A.E. Bogan, and E.E. Spamer. 1997. The taxonomy of Barney: evidence of convergence in hominid evolution. In: Marc Abrahams (ed.), The Best of Annals of Improbable Research (AIR). W.H. Freeman and Co., New York. pp. 107-112.
  • Mishler, B.D. and E.C. Theriot. 2000. The Phylogenetic Species Concept sensu Mishler and Theriot: Monophyly, Apomorphy, and Phylogenetic Species Concepts. Ch. 4 (pp. 44-54) in Q.D. Wheeler and E. Meier. Species Concepts and Phylogenetic Theory: A Debate. Columbia University Press. 230 pp.
  • Edgar, S.M., and E.C. Theriot. 2003. Heritability of mantle areolar characters in Aulacoseira subarctica (Bacillariophyta). Journal of Phycology 39: 1057-1066.
  • Rines, J.E.B., and E.C. Theriot. 2003. Systematics of Chaetocerotaceae (Bacillariophyceae). I. A Phylogenetic Analysis of the Family. Phycological Research 51: 83-98.
  • Goertzen, L.R., and E.C. Theriot. 2003. Effects of outgroup selection, taxonomic sampling, character weighting, and combining data on interpretation of relationships among the heterokont algae. Journal of Phycology 39(2): 423-439.
  • Edgar, S.M., and E.C. Theriot. 2004. Phylogeny of Aulacoseira (Bacillariophyta) based on morphology and molecules. Journal of Phycology 40: 772-788.
  • Tapia, P. M., E. C. Theriot, S. C. Fritz, F. Cruces and P. Rivera. 2004. Distribution and morphometric analysis of Cyclostephanos andinus comb. nov., a planktonic diatom from the Central Andes. Diatom Research 19: 311-327.
  • Theriot, E.C., S.C. Fritz, C. Whitlock, and D.J. Conley. 2006. Late-Quaternary rapid morphological evolution of an endemic diatom in Yellowstone Lake, Wyoming. Paleobiology 23(1): 38-54.