| Current Research | Publications | Contact | Photography |
See also the Steppan Lab site
Prospective Grad Students:
My research is generally question rather than taxon oriented, so grad students in my lab group are encouraged to develop independent research programs that may involve, for example, phylogenetics, biogeography, morphological evolution, or comparative quantitative genetics. While my taxonomic expertise is with muroid rodents, particularly the South American sigmodontines, past and present students have worked on carnivores, marsupials, frogs, salamanders, plants, cnidarians, and bivalves. Currently, grant support is available for several years for a grad student working on the diversification of muroid rodents.
My fundamental goal is to understand the evolutionary processes that promote biological diversity. My research attempts to bridge the micro- and macroevolutionary scales and apply process based models to understand and explain large-scale patterns. To address this long term goal, my research program involves studying highly diversified groups of mammals at a range of hierarchical levels. Currently, my focus is on molecular phylogenetics and quantitative genetics. The techniques include phylogenetic analyses of morphological and DNA sequence data, comparative analyses of multivariate patterns of covariation, developing the comparative tools to test these multivariate patterns, analysis of geographic variation, and alpha level systematics of living and fossil material.
Molecular systematics, biogeography, and
diversification of muroid rodents, especially
South American Sigmodontinae and Old World
Developing bivalves as a model system for testing macroevolutionary methods
Phylogeography and specieation in Andean Phyllotis using multiple loci
Comparative quantitative genetics
Phylogenetics and speciation in Philippine forest mice Apomys
Systematics of sigmodontine mice: DNA sequencing, Morphology, Paleontology, Biogeography
Constraints on the evolution of the vertebral column in rodents.
phylogeography and speciation in dwarf
salamanders (Eurycea) of the
Stephanie Martin: morphological adaptations of teeth in Old World mice Murinae
Nathanael Herrera: molecular phylogenetics of cockles and giant clams (Cardiidae, Bivalvia)
Jim Cooper (MS 2000; now a post-doc at Syracuse): developmental constraints and the evolution of marsupial limb diversity.
Brian Storz (MS 2003, now Asst. Prof. Centre College): adaptive plasticity and systematics in spadefoot toads.
James Albright: (MS 2004) phylogeography of Phyllotis.
Jenner Banbury: phylogeography and systematics.
|The primary focus of current research in my lab is molecular systematics of various diverse rodent groups. These include the Muroidea (mice, rates, hamsters, and relatives), subfamily Sigmodontinae (Neotropical mice and rats), Sciuridae (squirrels), and several genera within these groups, such as Apomys, Marmota, and Phyllotis. These phylogenies then form the framework for several comparative studies of quantitative genetics, vertebral evolution, and biogeography. We are also developing a new project in bivalves.|
Multigene phylogeny and diversification of the muroid rodents. Partly in collaboration with Ron Adkins at the Univ. Tennessee, Memphis, we are conducting a large sequencing effort to resolve one of the most intractable problems in mammals by dense taxon sampling, a large amount of slowly evolving sequence data, and developing new genes for mammalian phylogenetics. We are curently expanding our 300 species phylogeny to 600 species. We will be using these phylogenies to understand morphological (dental and cranial shape) diversification, biogeography, and the tempo of diversification. (See publication page for some Results)
Bivalves in Time and Space: We are developing bivalves as a model system for macroevolutionary studies in conjunction with Dave Jablonski (Univ. Chicago), Rˆºdiger Bieler (Field Museum), John Huelsenbeck (UC Berkeley), Paula Mikkelsen (Paleontological Research Institution), and Jan Johan ter Poorten (Zoological Museum, Univ. Amsterdam). Collectively, we are producing a combined molecular and morphological phylogeny of extant and many extinct species to test methods of ancestral state reconstruction, molecular clock dating, and biogeographic reconstruction, and models of spatial diversification. Our lab’Äôs contribution is overall coordination and the molecular data. See the BiTS website for more information.
Phylogeography and quantitative genetics in Phyllotis. In collaboration with Angel Spotorno and Laura Walker (Universidad de Chile) and Oswaldo Ramirez (Universidad de Heredia Cayetano, Lima) I am conducting phylogenetic analyses of multiple mitochondrial and nuclear genes for the Phyllotis darwini species group. Detailed population level sampling is testing species limits and biogeographic hypotheses, particular the role of the Andes on speciation patterns. Controlled breeding programs in four species will be used to estimate genetic variance-covariance (G) matrices to examine how G matrices evolve. These G matrices in turn will calibrate phenotypic covariance matrices from over 30 populations.
Phylogeny and historical
biogeography in Apomys. Apomys
is an endemic Philippine forest mouse (Murinae)
that has diversified on the many islands of the
Philippines. In collaboration with Larry Heaney
(Field Museum of Natural History) we are
producing a molecular phylogeny for the genus
using cyt b (Steppan et
al. 2004) and four nuclear genes. We are then
using the phylogeny to test models of historical
biogeography based on Pleistocene sea level
Constraints on the
evolution of the vertebral column in rodents.
I am studying the role of developmental
constraints on the evolution of the vertebral
column of rodents, focusing on the tail. Many
comparative studies of developmental constraints,
adaptation, key innovations, and the like, are
hampered by a lack of statistical power stemming
from the relatively small number of data points.
I am focusing on the tail of speciose mammalian
groups to maximize the sampling of morphological
transitions during evolution. The key questions
are whether there is a bias shaping the evolution
of the vertebral column and if one component of
morphology appears favored due to genetic or
developmental biases. To provide the framework or
the comparative analyses, I have composited a
phylogeny for over 400 species of myomorph
rodents from published phylogenies and mapped
vertebral characters onto it.
Frequency of Evolutionary Transitions in Rib Number
A list of publications can be found on this page with links to paper summaries, figures, and full-text pdf files.
|A distributed Internet project providing comprehensive and integrated information about phylogeny and biodiversity, developed by David and Wayne Maddison, Univ. of Arizona. My contribution includes Rodentia and the superfamilies Muroidea (mice, rats, hamsters, etc...), Sciuroidea (squirrels) and various subgroups.|
|Tree of Life Home
My contributions to the Tree of Life (rodent pages)
|Ph.D.||1995.||University of Chicago. Evolutionary Biology|
|M.S.||1992.||University of Chicago. Evolutionary Biology.|
|M.A.||1988.||San Diego State University. Geography|
|B.A.||1983.||University of California, Berkeley. Biology and Geography|
|Ecology and Evolution at FSU
Department of Biological Science
Florida State University
Tallahassee, FL 32306-1100
A selection of photographs from my portfolio.
Colonnade, Ayia Triadha
Images are for viewing only. Reproduction or electronic distribution without written consent is prohibited.
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