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Most large-scale evolutionary questions require an understanding of history, but analyses based exclusively on extant taxa require inferences whose uncertainties are broad or poorly understood. One of the few groups where methods can be developed and tested directly against historical data are bivalves, which are abundant today, rich in diversity, and have a long history documented by an excellent fossil record. The goal of this project is to develop bivalves as a preeminent model for macroevolutionary studies. The project will address species-level evolution over time in Bivalvia. More importantly, we will test and develop generally applicable methods for comparative analysis of organisms. All studies will be conducted on two not-closely related clades, to estimate the generality of the results. This research will provide four primary contributions to evolutionary biology. (1) Estimate phylogenies for two diverse family-level clades (Cardiidae and the pitarine group in Veneridae) using a combination of multiple genes and morphological characters. Focus in each clade will be on 100 extant species, ca. 60 morphological characters, and five genes (both mitochondrial and nuclear). (2) Integrate the extensive fossil records for the two clades by estimating combined-data phylogenies, adding 50-100 extinct species to each extant combined-data set. (3) Reconstruct temporal and geographic diversification patterns using the tree from (2) to assign all fossil occurrences to clades. The fossil occurrence data set will consist of thousands of entries, with new data supplementing our existing database. The dense fossil sampling in the combined-data phylogenies will provide the framework for step (4), which will test the accuracy of three principal macroevolutionary methods: molecular clock dating, ancestral state reconstruction, and historical biogeographic reconstruction. Simulations under different models of character/range evolution will estimate expected performance. We will cross-validate and rarefy the combined-data sets, subsampling fossils down to levels typical of macroevolutionary studies, to compare to the "known" dates/traits/ranges from the integration (2) and (3). Only the exceptional fossil record of bivalves makes it possible to treat the combined-data estimate of ancestral values as "known." The full integration of these three data sets (molecular, extant and extinct morphological, fossil occurrence) with macroevolutionary diversification models and parallel tests of the three primary macroevolutionary methods will yield significant insights on the spatial and temporal dynamics of a major marine group, and establish bivalves as a key model system for macroevolution.
BiTS is a collaboration among Scott Steppan (FSU, molecular systematics), Rüdiger Bieler (Field Museum, morphological systematics), Paula Mikkelsen (Paleontological Research Institution, morphological systematics), Jan Johan ter Poorten (Netherlands, morphological systematics of cardiids), David Jablonski (Univ. Chicago, paleobiology), and John Huelsenbeck (UC Berkeley, computational systematics).
Post-doctoral position on bivalve molecular phylogenetics and macroevolution
A one to two-year NSF-funded post-doctoral position is available starting as early as August 2009 in the lab of Scott Steppan at Florida State University on the molecular phylogenetics of cardiid and pitarine bivalves. The position is part of a larger project (Bivalves in Time and Space) developing bivalves as a model clade for macroevolutionary studies, taking advantage of their excellent fossil record to test methods of molecular clock dating, ancestral state reconstruction, historical biogeography, and detecting spatial and temporal trends in evolution. The specific responsibilities will involve sequencing 200 species for multiple nuclear genes and conducting phylogenetic analyses. The successful applicant will also participate in semiannual meetings and possible collaborations with other members of the research team who are working on the morphological, paleontological, and computational components.
The Ecology and Evolution program is a highly interactive and supportive environment that works closely with the Computational Evolutionary Biology group in the Dept. of Scientific Computing.
Applicants should have a Ph.D. in evolution, systematics, or related field and be proficient in PCR, DNA sequencing, and phylogenetic analysis. Experience with mollusks preferable. Salary will start at $38,500 and start date is negotiable. Review of applications will begin June 15. Additional information on the Steppan Lab and more details about the project are available from http://bio.fsu.edu/~steppan/, and on the Ecology and Evolution group at http://www.bio.fsu.edu/ee/index.html. Applicants should submit a cover letter, CV, statement of research interests, and request three letters of recommendation (please include the names and contact information for the three references in the cover letter or CV).
For more information, contact
Dr. Scott Steppan
Department of Biological Science
Florida State University
Tallahassee, FL 32306-4295
e-mail: steppan@bio.fsu.edu
phone: (850) 644-6536
fax: (850) 644-9829
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