Biological Science Faculty Member
Dr. Scott J. Steppan
PhD Univ. of Chicago, 1995 MS SDSU, 1989
Graduate Faculty Status
Research and Professional Interests:
My research is focused on understanding the origin of biological diversity. To address this long-term goal, I study highly diversified groups of animals (especially rodents and bivalves) ranging from population to ordinal levels. I reconstruct the phylogenetic relationships of these diverse groups to use as the framework for other analyses of diversification. My primary groups of interest are the muroid rodents and bivalves. Muroids are by far the most diverse group of mammals with 1,600 species, and my work focuses on them as well as various sub-groups, especially the South American sigmodontine mice (>360 species), the Andean leaf-eared mice, Phyllotis, and the Philippine forest mice Apomys. Among bivalves, we are collaborating with several labs to use them as a model clade for macroevolutionary studies of phylogenetics, diversification, and testing phylogeny-based reconstructions. These various phylogenies are used to study morphological evolution, patterns of diversification, biogeography, and comparative quantitative genetics. Our techniques include phylogenetic analyses of DNA sequence (primarily large data sets with multiple nuclear genes) and morphological data, comparative analyses of covariation among traits, developing the comparative tools to test these multivariate patterns, analysis of geographic variation, and alpha-level systematics of living and fossil material. Go to my Home Page link above for more information.
I welcome students working in any of the general fields described above. Because my research is fundamentally question generated and not taxon based, students need not work on the same groups of animals that form the core of my current research.
Selected Publications:2022. Steppan,, S. J., Meyer, A. A., Barrow, L. N., Alhajeri, B. A., Al-Zaidan, A., Gignac, P. M., and Erickson, G. M. Phylogenetics and the evolution of terrestriality in mudskippers (Gobiidae: Oxudercinae). Molecular Phylogenetics and Evolution.
2022. Saltzberg, C. J., Costa, B. M. A., Chipps-Walton, L., Walker, L., Spotorno, A., and Steppan, S. J. Comparative quantitative genetics of the pelvis in four-species of rodents and the conservation of genetic covariance and correlation structure. Evolutionary Biology. 49 (1):71-84. DOI: 10.1007/s11692-022-09559-z
2021 Bangs, M. R. and Steppan, S.J. A rodent Anchored Hybrid Enrichment probe set for a range of phylogenetic utility – from order to species. Molecular Ecology Resources. 2021:1-8.
2020 Storz, J.F., Quiroga-Carmona, M., Opazo, J.C., Bowen, T., Farson, M., Steppan,, S. J., and D’Elía, G. Discovery of the world’s highest-dwelling mammal. Proceedings of the National Academy of Sciences. 117: 18169–18171. doi/10.1073/pnas.2005265117.
2019 Rowe, K. C., Achmadi, A. S., Fabre, P-H., Schenk, J. J., Steppan,, S. J., and Esselstyn, J. A. Oceanic islands of Wallacea as a source for dispersal and diversification of murine rodents. Journal of Biogeography. 46:2752–2768. DOI: 10.1111/jbi.13720
2017 Steppan, S. J. and Schenk, J. J. Muroid rodent phylogenetics: 900-species tree reveals increasing diversification rates. PLoSOne. 12(8): e0183070. doi.org/10.1371/journal.pone.0183070
2017 Wray, K. P., and Steppan, S. J. Historical biogeography and diversification in a major lineage of salamanders (Plethodontidae: Spelerpinae). Journal of Biogeography 44:797-809.
2016 Heaney, L.R., Balete, D.S., Duya, M.R.M., Duya, M.V., Jansa, S. A., Steppan, S.J., Rickart, E.A. Doubling diversity: a cautionary tale of previously unsuspected mammalian diversity on a tropical oceanic island. Frontiers in Biogeography: 1-19.
2016 Martin, S.A., Alhajeri, B. H., and Steppan, S.J. Dietary adaptations in teeth of murine rodents (Muridae). Biological Journal of the Linnean Society. 119: 766-784.
2014 Justiniano, R., Schenk, J.J., Balete, D.S., Rickart, E.A., Esselstyn, J.A. Heaney, L.R., and Steppan, S.J. Testing diversification models of endemic Philippine forest mice (Apomys) with nuclear phylogenies across elevational gradients reveals repeated colonization of isolated mountain ranges. Journal of Biogeography. 42:51-64.
2014 Schenk, J.J., and Steppan, S.J. Too long to read: Assessing the motivation behind graduate student attendance in reading groups. Journal of College Science Teaching. 44(2):64-69.
2013 Schenk, J.J., Rowe, K.C., and Steppan, S.J. Ecological opportunity and incumbency in the diversification of repeated continental colonizations by muroid rodents. Systematic Biology 62(6): 837-864.
2012 Erickson, G. M., Gignac, P. M., Steppan, S. J., Lappin, A. K., Vliet, K. A., Brueggen, J. D., Inouye, B. D., Kledzik, D., Webb, G. J. W.. Insights into the ecology and evolutionary success of crocodilians revealed through bite force and tooth pressure experimentation PLoS ONE 7(3): e31781. doi:10.1371/journal.pone.0031781.
2011 Lawrence R. Heaney, Danilo S. Balete, Eric A. Rickart, Phillip A. Alviola, Mariano Roy M. Duya, Melizar V. Duya, M. Josefa Veluz, Lawren VandeVrede, and Scott J. Steppan. Seven new species and a new subgenus of forest mice (Rodentia: Muridae: Apomys) from Luzon Island, Philippines. Fieldiana: Life and Earth Sciences 2: 1-60.
2010 Cooper, J., and Steppan, S. J. Developmental constraint on the evolution of marsupial forelimb morphology. Australian Journal of Zoology. 58: 1-15.
2010 van der Linde, K., Houle, D., Spicer, G., and Steppan, S. J. A supermatrix analysis of the family Drosophilidae. Genetics Research. 92: 25-38.
2008 Harshman, J., Braun, E. L., Braun, M. J., Huddleston, C. J., Bowie. R. C. K., Chojnowski, J. L., Hackett, S. J., Han, K-L., Kimball, R. T, Marks, B. D., Miglia, K. J., Moore, W. S., Reddy, S., Sheldon, F. H., Steadman, D. W., Steppan, S. J., Witt, C. J., and Yuri, T. Phylogenomic evidence for multiple losses of flight in ratite birds. Proceedings of the National Academy of Science 105 (36): 13462-13467.
2008 Good, J. M., Hird, S., Demboski, J. R., Steppan, S. J., Martin-Nims, T.R., and Sullivan, J. Ancient hybridization and mitochondrial capture between two distantly related species of chipmunks (Tamias: Rodentia). Molecular Ecology. 17(5):1313-1327.
2007 Steppan, S. J., Ramirez, O., Banbury, J., Huchon, D., Pacheco, V., Walker, L, and Spotorno, A.O.. A molecular reappraisal of the systematics of the leaf-eared mice Phyllotis and their relatives. Pp. 799-820 in The quintessential naturalist: honoring the life and legacy of Oliver P. Pearson (Kelt, D. A., E. P. Lessa, J. A. Salazar-Bravo, and J. L. Patton, eds.). University of California Publications in Zoology 134.
2004 Steppan, S. J., Adkins, R., and Anderson, J. Phylogeny and divergence date estimates of murid rodents based on multiple nuclear genes. Systematic Biology. 53(4):533-553.
2004 Holliday, J. A. and Steppan, S. J. Evolution of hypercarnivory: the effect of specialization on morphological and taxonomic diversity. Paleobiology. 30(1):108-128.
2004 Steppan, S. J., Storz, B. L., and Hoffmann, R. S. Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1. Molecular Phylogenetics and Evolution. 30:703-719.
2002 Steppan, S.J., Houle, D., and Phillips, P.C. Comparative quantitative genetics: evolution of the G matrix. Trends in Ecology and Evolution. 17:320-327.
1997 Steppan, S.J. Phylogenetic analysis of phenotypic covariance structure. II. Reconstructing matrix evolution. Evolution. 51(2): 587-594.
1995 Steppan, S.J. Revision of the tribe Phyllotini (Rodentia: Sigmodontinae) with a phylogenetic hypothesis for the Sigmodontinae. Fieldiana: Zoology. n.s. 80:1-112.