Date of Thesis
Honors Thesis (Bucknell Access Only)
Bachelor of Science
Minor, Emphasis, or Concentration
Angela J. McDonnell
Jack F. Gallimore
Solanum, Solanaceae, Hybridization, Australia, Andromonoecy, Speciation
The 20+ taxa of the Solanum subgenus Leptostemonum “S. dioicum Group” sensu Bean of the Australian Monsoon Tropics (AMT) have undergone recent and rapid speciation. The group contains a broad range of breeding system expression and provides a model for studying evolutionary trends in angiosperms. Biogeography models suggest taxa in this group have likely undergone speciation following secondary contacts between disjunct populations at glacial refugial during glacial cycles. Restricted sampling and limited access to remote areas of the AMT has made phylogenetic comparisons challenging. In testing evolutionary and biogeographic models, we obtained 1,574 fruits from 4,496 ex situ infrageneric generic crosses involving four dioecious and twelve andromonoecious closely related taxa. The high success rate of hybrid fruit set supports current biogeographic models. We suggest speciation likely occurred as a result of geographic isolation as taxa diverged and occupied ecological niches across the AMT. Our data presents Australian Solanum as a unique system for studying breeding system evolution and barriers to reproduction.
Hayes, Daniel S., "Ex situ interspecies crossing rates infer importance of geographic barriers in speciation among closely related Solanum species of the Australian Monsoon Tropics" (2018). Honors Theses. 447.