Date of Thesis

Spring 2018

Thesis Type

Honors Thesis (Bucknell Access Only)

Degree Type

Bachelor of Science

Major

Biology

Minor, Emphasis, or Concentration

Cell Biology/Biochemistry

First Advisor

Christopher T. Martine

Second Advisor

Angela J. McDonnell

Third Advisor

Jack F. Gallimore

Keywords

Solanum, Solanaceae, Hybridization, Australia, Andromonoecy, Speciation

Abstract

The 20+ taxa of the Solanum subgenus LeptostemonumS. 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.

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