Timing the Evolution of Solanum Section Androceras
An excellent opportunity to work with colleagues at the Evolutionary Biology Centre, Uppsala University, including Mario Vallejo-Marin, and with Stacey D. Smith at the University of Colorado Boulder.
Background
Understanding when species diverged from one another is fundamental to evolutionary biology, as divergence times provide a temporal framework for studying speciation, trait evolution, and biogeographic history. In plants, estimating divergence times can be challenging due to hybridization, polyploidy, incomplete lineage sorting, and uneven taxon sampling. These challenges are particularly evident in species-rich genera such as Solanum, one of the largest genera of flowering plants.
Solanum section Androceras is a small but well-known clade of nightshade plants, comprising approximately 10–12 species distributed mainly in the Americas. The group has attracted attention due to its distinctive morphology, ecological diversity, and importance as a model system in studies of mating systems, floral evolution, and plant–pollinator interactions. Despite its prominence, Androceras is poorly represented in large-scale, time-calibrated phylogenies of Solanum, limiting our understanding of when key diversification events occurred.
Recent advances in molecular phylogenetics and the availability of multi-locus and genomic datasets provide new opportunities to estimate divergence times for under-sampled clades. By integrating existing sequence data with curated fossil and secondary calibration datasets, it is now feasible to place Androceras into an updated temporal framework using relaxed molecular clock approaches. Such analyses can clarify the timing of species divergences, provide context for ecological and evolutionary hypotheses, and identify gaps in current sampling.
This MSc project will focus on compiling available molecular data for Solanum section Androceras, reconstructing a phylogenetic tree, and estimating divergence times using established analytical tools. The project will contribute to ongoing efforts to improve Solanum phylogenies and provide a solid foundation for future comparative and genomic studies.
Aims
- Compile and curate available molecular sequence data for Solanum section Androceras
- Reconstruct a phylogenetic tree using multi-locus datasets
- Estimate divergence times using time-calibrated phylogenetic methods
- Compare new divergence estimates with previously published results
- Identify key uncertainties and data gaps for future research
Who should apply?
This project is suitable for MSc students with an interest in plant evolution, systematics, or biodiversity science. Applicants should be curious about evolutionary questions and comfortable working with data. Prior experience in phylogenetics or programming is helpful but not required—training will be provided.
Skills gained
- Phylogenetic reconstruction and interpretation
- Estimation of divergence times using time-calibrated trees (e.g. BEAST)
- Handling and curating molecular sequence datasets
- Basic data analysis and visualization in R
- Experience working with published and public biological datasets
Key References
González Ramírez I, Deanna R, Smith DS. Late Cretaceous origins for major nightshade lineages from total evidence timetree analysis. bioRxiv. 2025 Jul 22; doi:10.1101/2025.07.22.666174. Available from:
Särkinen T, Bohs L, Olmstead RG, Knapp S. A phylogenetic framework for evolutionary study of the nightshades (Solanaceae): a dated 1000-tip tree. BMC Evol Biol. 2013;13:214. doi:10.1186/1471-2148-13-214
Stern S, Bohs L. Phylogenetic relationships in Solanum section Androceras (Solanaceae). Syst Bot. 2010;35(4):825-34. doi:10.1600/036364410X539934
Vallejo-Marin, M., C. Walker, P. Friston-Reilly, L. Solis-Montero, and B. Igic. 2014. Recurrent modification of floral morphology in heterantherous Solanum reveals a parallel shift in reproductive strategy. Philos Trans R Soc Lond B Biol Sci 369:20130256.