Winteraceae
Floral Evolution in Winteraceae
My doctoral work on floral ontogeny and form in the basal angiosperm family Winteraceae was directed towards understanding, on a detailed and mechanistic level, how morphological diversity in flowers can arise. I showed that few developmental changes were needed to account for the evolution of floral diversity in the family. In particular, heterochronic changes (variation in the timing of initiation) of primordia, as well as their size relative to that of the floral meristem, gave rise to morphological differences between genera. Variation in floral meristem size and shape also led to morphological diversity within individual populations and even individual trees, leading to a remarkable array of phyllotactic patterns and organ number in developing flowers. This work involved extensive statistical analysis, allowing new insights into developmental patterns.
Much work remains to be done, especially in relating developmental changes to molecular phylogenies of the family. One question I have tackled has been the controversial systematic relationships of Tasmannia and Drimys, as successive authors have treated them as either a single genus or two separate genera. Morphological characters appear to unite the two genera but a combination of further molecular sampling and explicit comparison of competing phylogenetic hypotheses using likelihood tests and parametric bootstrapping rejects the combination of Tasmannia and Drimys. This conclusion was supported by floral developmental analysis of a number of species in the two genera. Other groups in the Winteraceae with just as interesting questions remain to be tackled!
Collaborators: Andrew Drinnan, University of Melbourne, Victoria, Australia.