Stevan J. Arnold
Curator of Amphibians and Reptiles
B.A., U California, Berkeley 1966
Ph.D., U Michigan, Ann Arbor 1972
E-Mail: email@example.com, Phone: 541-737-3705, FAX: 541-737-0501
Mailing Address: Department of Zoology, Oregon State University, Corvallis, Oregon 97331-2914.
COURSES TAUGHT (List and descriptions).
AREAS OF RESEARCH: phenotypic evolution, quantitative genetics, sexual selection, sexual isolation, protein evolution, molecular systematics.
STATEMENT OF RESEARCH INTERESTS (full length CV). The focus of research in my laboratory is on evolutionary processes and pattern in natural populations. I work mainly on snakes and salamanders:
Evolutionary processes in garter snakes.-The over-arching concept in the snake work is
to establish a bridge between evolutionary process (inheritance,
migration, selection) and pattern (geographic variation and species
differences). My recent work with snakes has emphasized the quantitative
inheritance of meristic traits (scale and vertebral counts). In
collaboration with Patrick C. Phillips (U. Oregon, Eugene),
I have been comparing patterns of multivariate inheritance among
populations and species of garter snakes. We have been searching - with
some success - for regularities in the evolution of inheritance and
environmental matrices that describe multivariate inheritance. The
significance of those regularities is that they can be used to
reconstruct historical patterns of selection and to test neutral models
for population differentiation - two important bridges between process
and pattern. The snake work is increasingly focused on comparing
inheritance matrices on a phylogenetic tree for garter snakes and their
relatives, natricine snakes. I have established a molecular lab at OSU
to work on the phylogeny of natricines at the population and species
levels. This systematic work is being pursued in collaboration with
Michael E. Pfrender (Utah State University, Logan),
Michael E. Alfaro
(Washington State University, Pullman), Robin Lawson (Calif. Acad. Sci.,
San Francisco), and Frank
A primary focus is to deduce the population and species phylogeny
of those taxa for which we have estimates of inheritance matrices (Thamnophis
couchii complex, T. elegans, T. radix, sirtalis, and their close
relatives) using mitochondrial and nuclear gene sequences. Aside from
clarifying the relationships of these taxa, a well-resolved molecular
phylogeny will allow us to test models for the evolution of inheritance
The evolution of the G-matrix.- In a related theoretical project, I am studying the evolution of inheritance matrices (G-matrices) by computer simulation in collaboration with Adam G. Jones (Texas A&M)and Reinhard Burger (Univ. Vienna). The goal of this project is to establish the conditions of selection, mutation, and population size that are most and least conducive to G-matrix stability.
Aging and stochastic demography in garter snakes.-
Anne M. Bronikowski
(Iowa State Univ.) and I are
continuing a demographic study of T. elegans that has been
underway for more than 25 years in the vicinity of Eagle Lake, Lassen
County, California. We have discovered two ecotypes with contrasting
profiles of age-specific growth, reproduction and mortality. We are using those ecotypes as a model for studying
senescence in natural populations (Amanda's
Snake Camp blog)..
In a related set of projects,
Mollie K. Manier
has completed her doctoral work at OSU on this system. Manier used
microsatellites to study population structure of T.
elegans and T. sirtalis and
their prey (Bufo boreas) in the Eagle Lake basin. In
the course of that work, she demonstrated strong selection on the
scalation and coloration traits that characterize the meadow and
lakeshore ecotypes in T. elegans.
In the course of that work, she demonstrated strong selection on the scalation and coloration traits that characterize the meadow and lakeshore ecotypes in T. elegans.
The evolution of salamander courtship
pheromones.- The salamander work is part of a larger project on the
evolution of courtship pheromones in plethodontid salamanders.
The courtship pheromones of these salamanders are cytokines (see
diagram below of pheromone - blue - threaded onto structually-similar human IL-6
, red) that
are either "vaccinated" into the female's circulatory system
by the enlarged premaxillary teeth of the courting male or delivered
into the female's vomeronasal organ (click here to view
video of olfactory delivery in Plethodon
Lynne Houck and her co-workers have shown that these pheromones
speed up the process of insemination.
The process of sperm transfer is shown in this
video of Plethodon shermani.
The process of sperm transfer is shown in this
video of Plethodon shermani.The goal of the project is to understand
courtship pheromones in the genus Plethodon at the level of
genes, proteins, physiology and behavior.
The project is headed by Lynne D. Houck
and consists of a molecular & biochemical team (at OSU and the
University of Louisville), a physiological team (at OSU, Univ. Oklahoma
and Univ. Bremen) and a behavior team (OSU).
The aim of the molecular work at OSU is to characterize pheromone
gene sequences in 30 species of Plethodon and deduce patterns of
selection at the codon level. We are also in the process of localizing and characterizing pheromone
receptors. The primary members of the molecular/biochemical team are
Steve Arnold, Frank Moore, Richard Watts (postdoc)
and Catherine Palmer (currently or formerly at OSU)
Feldhoff, Pam Wheeler-Feldhoff,
Ron Gregg, and
Maureen McCall (all at Louisville).
Our team also relies on help from
Hilary Godwin's lab (UCLA),
Amy Rosenzweig's lab (Northwestern University) and
The evolution of sexual isolation.- Louise S. Mead, Paul Hohenlohe, Josef Ueyda and I are collaborating on maximum likelihood and computer simulation studies of the evolution of sexual isolation. We are using a large data sets on sexual isolation in plethodontid salamanders (Desmognathus), darters (Etheostoma) and Drosophila as test cases.
CURRENT AND FORMER GRADUATE STUDENTS AND POSTDOCS (Click HERE for a list).
RESEARCH AND TRAINING SUPPORT (See CV for a list of grants and awards).
HERPETOLOGICAL COLLECTIONS AT OSU (Click HERE for a description).
REPRESENTATIVE RECENT PUBLICATIONS (Complete list + pdfs, Google Scholar, ResearchGate):
Estes, S. and S. J. Arnold. 2007. Resolving the paradox of stasis: models with stabilizing selection explain evolutionary divergence on all timescales. American Naturalist 169: 227-244. pdf supplementary material Hendry 2007 News&Views.
Manier, M. K., C. M. Seyler, and S. J. Arnold. 2007. Adaptive divergence within and between ecotypes of the terrestrial garter snake, Thamnophis elegans, assessed with Fst-Qst comparisons. J. Evolutionary Biology 20: 1705-1719. pdf Figure 1a Figure 1b Appendix S1 Appendix S2
Jones, A. G., S. J. Arnold and R. Bürger. 2007. The mutation matrix and the evolution of evolvability. Evolution 61: 727-745. pdf
Hohenlohe, P. A. and S. J. Arnold. 2008. MIPoD: a hypothesis-testing framework for microevolutionary inference from patterns of divergence. American Naturalist 171: 366-385. pdf Appendix MIPoD software
Arnold, S. J., R. Bürger, P. A. Hohenlohe, B. C. Ajie and A. G. Jones. 2008. Understanding the evolution and stability of the G-matrix. Evolution 62: 2451-2461. pdf spreadsheet
Uyeda, J. C., S. J. Arnold, P. A. Hohenlohe, and L. S. Mead. 2009. Drift promotes speciation by sexual selection. Evolution 63: 583-594. pdf Explications and simulation run examples Supplementary appendix and tables Errata
Hohenlohe, P. A. and S. J. Arnold. 2010. The dimensionality of mate choice, sexual isolation and speciation. Proceedings of the National Academy of Sciences U.S.A. 107: 16583-165588. pdf Supplementary Material
Uyeda, J. C., T. F. Hansen, S. J. Arnold, and J. Pienaar. 2011. The million-year wait for macroevolutionary bursts. Proceedings of the National Academy of Sciences U.S.A. 108: 15908-15913. pdf Supplementary Material
Miller, D. A., W. R. Clark, S. J. Arnold, and A. M. Bronikowski. 2011. Stochastic population dynamics and life-history evolution in the western terrestrial garter snake. Ecology 92: 1658-1671. pdf
RECENT PRESENTATIONS AND WORKSHOPS:
Newt World.- An outreach activity that is part of Discovery Days at Oregon State University!
Intelligent Design and Evolutionary Biology: When Worlds Collide - 2005 Gilfillan Lecture at OSU
(to see the notes for each slide, save this file and then open it)
Mating Systems Evolution - ppt and parental table spreadsheet for a talk at a conference sponsored by the Wenner-Gren Foundation and the Swedish Academy of Science in Kristineberg, Sweden in 2007
Measuring Evolution, ppt for a talk at a workshop sponsored by the Norwegian Academy of Science and Letters, October 2008, Oslo, Norway
Simulation Studies of G-matrix Stability and Evolution, ppt for a talk given at an ESI workshop sponsored by the Vienna Science and Technology Fund, July 2009, Vienna, Austria
Evolution Along Selective Lines of Least Resistance, ppt for talk at the August, 2009 ESEB meeting in Torino, Italy
NESCent Academy Workshop in Evolutionary Quantitative Genetics, August, 2012, Durham, NC
Phenotypic Evolution: the Emergence of a New Synthesis, ppt for American Society of Naturalists Presidential Address, 9 July 2012, First Joint Congress on Evolutionary Biology, Ottawa, Canada