Margaret B. Ptacek


Contact Information

Phone: 864 656-6964
FAX: 864 656-0435


  • Ph.D. University of Missouri-Columbia, 1991
  • M.S. Emporia State University, 1984
  • B.S. Emporia State University, 1981

Research Interests

My main research interests lie at the intersection of behavioral ecology, population genetics and speciation. Specifically, I am interested in processes that control genetic divergence among populations and the contributions of these processes to local adaptation and speciation. My work investigates mechanisms causing divergence among natural populations and addresses questions regarding gene flow and its influence on phylogenetic relationships among populations and closely related species. In my research, I apply molecular techniques to phylogeny reconstruction and use these phylogenies to address a variety of issues of significance in evolutionary ecology.

I am currently involved in two major projects. The first project entails examining speciation in a group of poeciliid fishes, the subgenus Mollienesia, in which sexual selection may have played a prominent role. The mollies are an excellent group in which to study speciation because enormous variation exists in male morphology and mating behaviors both at the interspecific level and among populations within certain molly species. I am focusing my research on the evolution of the behaviors and morphology associated with the sailfin molly phenotype using the three interrelated approaches of phylogeny reconstruction, comparative behavioral studies and genetic hybridization experiments.

The second project, in collaboration with Rick Blob in Biological Sciences, examines the evolutionary forces responsible for adaptive differentiation of morphology and climbing performance in waterfall climbing gobies of the Hawaiian Islands. These freshwater fishes have a unique life history termed amphidromy, where larvae hatch upstream but are quickly swept to the ocean, where they develop up to six months before returning to freshwater. For three goby species, returns require climbs of vertical waterfalls tens of meters tall before reaching adult habitats. Larvae from different islands mix in the ocean, leading to gene flow between subpopulations. However, the environments to which juveniles return differ strongly between the oldest (Kaua’i) and youngest (Hawai’i) islands. Hawaiian waterfalls are close to shore, placing a premium on climbing ability to escape non-climbing predators; in contrast, Kauaian falls are far inland, placing a premium on predator evasion as fish migrate upstream. Biomechanical models predict these contrasting demands will select for divergent body shapes (low-height to reduce drag on Hawai’i vs. tall-bodied to generate evasive thrust on Kaua’i). Thus, the potential exists for trade-offs in selection for morphology that improves climbing performance versus performance in escaping predators across these divergent habitats. We are currently integrating studies of morphology, performance, and genetic divergence with the significance of local selection pressures between habitats in the climbing goby Sicyopterus stimpsoni. These studies will provide a model for research on the interactive mechanisms promoting the evolution of organismal form and function in response to environmental demands. 

Selected Publications

  • Kozak, H. L., Cirino, L. A., and Ptacek, M. B. 2008. Female mating preferences for male morphological traits used in species and mate recognition in the Mexican sailfin mollies, Poecilia velifera and P. petenensis. Behavioral Ecology, 19:463-474. PDF Download
  • Hankison, S. J. and Ptacek, M. B. 2008. Geographical variation of genetic and phenotypic traits in the Mexican sailfin mollies, Poecilia velifera and P. petenensis. Molecular Ecology, 17:2219-2233. PDF Download
  • Gunnell, K., Tada, M. K., Hawthorne, F. A., Keeley, E. R., and Ptacek, M. B. 2008. Geographic patterns of introgressive hybridization between native Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) and introduced rainbow trout (O. mykiss) in the South Fork of the Snake River watershed, Idaho. Conservation Genetics, 9:49-64. PDF Download
  • Hankison, S. J., and Ptacek, M.B. 2007. Within and between species variation in male mating behaviors in the Mexican sailfin mollies Poecilia velifera and P. petenensis. Ethology, 113:802-812. PDF Download
  • Hankison, S. J., Childress, M. J., Schmitter-Soto, J. J., and Ptacek, M. B. 2006. Morphological divergence within and between the Mexican sailfin mollies, Poecilia velifera and P. petenensis. Journal of Fish Biology, 68:1610-1630. PDF Download
  • Jones, M. T., Voss, S. R., Ptacek, M. B., Weisrock, D. W. and Tonkyn, D. W. 2006. River Drainages and phylogeography: an evolutionary significant lineage of shovel-nosed salamander (Desmognathus marmoratus) in the Southern Appalachians. Mol. Phylo. Evol., 38:280-287. PDF Download
  • Ptacek, M. B., Childress, M. J. and Kittell, M. M. 2005. Characterizing the mating behaviours of the Tamesí molly, Poecilia latipunctata: a sailfin with shortfin morphology. Animal Behaviour, 70:1339-1348. PDF Download

Recent Courses

  • Fall Semester
    • BIOSC 335 Evolutionary Biology
    • BIOSC 871 Special Topics: Speciation

Graduate Students

  • Stephanie Loveless
  • Jennifer Seda
  • Kristine Moody

Professional Affiliations

  • Society for the Study of Evolution
  • Animal Behavior Society