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Position: Associate Professor, Florida State University

See also the Steppan Lab site

For 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.

RESEARCH PROGRAM

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.

Research Projects

Molecular systematics, biogeography, and diversification of muroid rodents, especially South American Sigmodontinae and Old World Murinae
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.

Graduate Student Research

Kenny Wray: phylogeography and speciation in dwarf salamanders (Eurycea) of the south-eastern US
Stephanie Martin: morphological adaptations of teeth in Old World mice Murinae
Nathanael Herrera: molecular phylogenetics of cockles and giant clams (Cardiidae, Bivalvia)

Past graduates:
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.

CURRENT RESEARCH

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), Rdiger 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 labs 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 fluctuations.

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


PUBLICATIONS

A list of publications can be found on this page with links to paper summaries, figures, and full-text pdf files.


TREE OF LIFE

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 Page
My contributions to the Tree of Life (rodent pages)


EDUCATION

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

850.644.6536
steppan@bio.fsu.edu
My departmental page (http://www.bio.fsu.edu/faculty-steppan.php)
Steppan Lab Website



 PHOTOGRAPHY

A selection of photographs from my portfolio.

Colonnade, Ayia Triadha Monastery, Crete.
Click on the thumbnail to visit my photography website.

Images are for viewing only. Reproduction or electronic distribution without written consent is prohibited.


Last saved December 21, 2009
Page © 1997, 1998 Scott Steppan
Tree of Life icon © 1996 David Maddison and Wayne Maddison.

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