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Evolution of Plant Breeding Systems: Male Form and Function in Solanaceae Flowers

Supervisors: Beverley Glover (Plant Sciences) and Sandy Knapp (Natural History Museum)

Reference Code: B426

Importance of the area of research:

The enormous species diversity of the angiosperms was described by Darwin as “an abominable mystery”. Part of the explanation lies with the ways in which different plant species are reproductively isolated from one another, as a result of divergence of floral morphology and consequent differences in their interactions with pollinating animals. The genus Solanum is a particularly intriguing case, containing around 1500 species with superficially similar flower morphology. They are pollinated by pollen-gathering bees, through a specialised system of poricidal stamens, known as buzz pollination. This project aims to understand radiation and speciation in Solanum by developing an integrated understanding of the morphological, functional and developmental processes underlying variation in stamen morphology.

Project summary:

This project will focus on understanding evolution of stamen form and function in Solanum, and relating stamen form and function to species diversification. Although all species in the genus reward pollen-collecting bees from poricidally-dehiscing stamens, the position of those stamens influences pollen placement on the animal's body, effectively isolating different Solanum species from one another. This project will focus on the integration of the stamens as a single unit, through varying epidermal cell morphology, and on the ways in which different stamen epidermal morphologies influence bee grip and positioning on the flower. We will map these traits onto well-resolved Solanum phylogenies to identify evolutionary transitions and direction, and explore differential function and developmental control of contrasting morphologies.

What the student will do:

The student will use light and scanning electron microscopy to score stamen epidermal morphology and macroscale stamen position and shape in the genus Solanum, using living collections at several Botanic Gardens and herbarium material from the Natural History Museum. Traits will be character mapped using Bayesian models to established phylogenies of Solanum. Additional phylogeny reconstruction will be undertaken where necessary, using conventional molecular markers for the genus. The student will then select sister pairs with contrasting stamen morphologies to conduct two different types of analyses. (1) Functional characterization of pollinator response to contrasting stamen morphologies will be explored in a controlled environment, using our bumblebee behaviour lab. We will test whether sister species, or replica flowers presenting the key differential traits of sister species, elicit different foraging behaviours from pollen-collecting bees. (2) Developmental genetic analysis of the generation of contrasting morphologies will be explored. We will use molecular genetic techniques, including transgenic approaches and transcriptomic work, to determine how key traits are built.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

  • Glover, B.J., S. Bunnewell & C. Martin, 2004. Convergent evolution within the genus Solanum: the specialised anther cone develops through alternative pathways.  Gene, 331, 1-7. ;Covered by Nature News and Views, 428, 813.
  • Knapp, S., 2010.  "On various contrivances": pollination, phylogeny and flower form in the Solanaceae. Philosophical Transactions of the Royal Society B, 365, 449-460.
  • Whitney, H., L. Chittka, T. Bruce & B.J. Glover, 2009. Conical Epidermal Cells Allow Bees to Grip Flowers and Increase Foraging Efficiency. Current Biology, 19, 1-6.

Follow this link to find out about applying for this project.