Plant systematics, molecular evolution

1999 – Ph.D., Iowa State University

My research interests are in the fields of Plant Systematics and Molecular Evolution. My systematic studies focus on the plant family Malvaceae, especially the genus Hibiscus and the tribe Malveae. We use phylogenetic analyses of molecular data (DNA sequences) to reconstruct species relationships. The DNA sequences we use depend on the particular phylogenetic question, but include chloroplast genes and non-coding regions, and low-copy nuclear-encoded genes. Phylogenetic trees resulting from these studies are used to assess and revise classification systems, to evaluate character evolution and biogeography, and to study the process of polyploid speciation and evolution. While my particular interests are in the phylogenetics of Malvaceae, my students often study other groups of plants.  Students in my lab have worked on Sarracenia (Sarraceniaceae), Prunus (Rosaceae), Sida (Malvaceae), Gratiola (Plantaginaceae), Thaspium (Apiaceae), and Minuartia (Caryophyllaceae). A common theme running through all of these projects is the problem of reconstructing relationships among closely related species. Problems like these require an approach that blends traditional phylogenetic analyses with population genetics and phylogeography.

My interests in Molecular Evolution are in the area of gene family evolution of nuclear-encoded protein-coding genes. Molecular evolutionary studies seek to document the rates and patterns of gene evolution. The bulk of nuclear protein-coding genes exist in gene families – multiple genes with similar sequences and functions, but related through gene duplication events. Understanding the origins these genes as well as the rates and patterns of evolution within them is the first step to understanding the evolutionary and functional significance of these gene families. To study these questions we use a couple of different model systems: Gossypium(cotton) and Arabidopsis. In Gossypium we’re exploring the effect of polyploidization on gene family evolution, while in Arabidopsis we’re evaluating the correlation between genetic and phenotypic variation in a set of natural populations.

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• Estes, D. and R.L. Small. 2007. Two new species of Gratiola (Plantaginaceae) from eastern North America and an updated circumscription for Gratiola neglecta. Journal Botanical Research Institute of Texas 1:149-170.
• Placyk, J.S., G.M. Burghardt, R.L. Small, R.B. King, G.S. Casper, and J.W. Robinson. 2007. Post-glacial colonization of the Great Lakes region by the common gartersnake (Thamnophis sirtalis) inferred from mtDNA sequences.Molecular Phylogenetics and Evolution 43:452-467.
• Shaw, J., E.B. Lickey, E.E. Schilling and R.L. Small. 2007. Comparison of whole chloroplast genome sequences to choose noncoding regions for phylogenetic studies in angiosperms: the tortoise and the hare III. American Journal of Botany94:275-288.
• Shaw, J. and R.L. Small. 2005. Chloroplast DNA phylogeny and phylogeography of the North American plums (Prunus subgenus Prunus section Prunocerasus, Rosaceae). American Journal of Botany 92:2011-2030.
• Small, R.L., E.B. Lickey, J. Shaw, and W.D. Hauk.  2005.  Amplification of noncoding chloroplast DNA for phylogenetic studies in lycophytes and monilophytes with a comparative example of relative phylogenetic utility from Ophioglossaceae. Molecular Phylogenetics and Evolution 36:509-522.
• Ayoub, N.A., S.E. Riechert, and R.L. Small.  2005.  Speciation history of the North American funnel web spiders, Agelenopsis (Araneae: Agelenidae): phylogenetic inferences at the population-species interface. Molecular Phylogenetics and Evolution 36:42-57.
• Shaw, J. E.B. Lickey, J.T. Beck, S.S. Farmer, W. Liu, J. Miller, K.C. Siripun, C.T. Winder, E.E. Schilling, and R.L. Small.  2005.  The tortoise and the hare II: relative utility of 21 noncoding chloroplast DNA sequences for phylogenetic analysis.American Journal of Botany 92:142-166.