Geraniaceae research projects
Molecular systematics of Pelargonium sect. Hoarea
Dr. F.T. Bakker - NHN Wageningen UR branch; Dr. E. Marais - University of Stellenbosch, South Africa
Pelargonium
L'Hér. is a predominantly South African genus in which both vegetative and floral
morphology underwent extensive evolution, especially within the Cape winter rainfall
region and probably since the late-Pliocene. This has resulted in nested radiations of
closely related species, for instance the section Hoarea (Sweet) DC. clade
(comprising approximately 80 geophytic species) constitutes a secondary radiation within
the genus, the primary being a general 'winter rainfall clade'. Since a robust molecular
phylogenetic hypothesis for Pelargonium is now available, we know that section Hoarea
comprises a monophyletic group, possibly in a most derived position within the genus, for
which sister taxa have been identified. Within the Hoarea clade independent trends
of floral evolution (possibly reflecting pollinator-pressure) and three basic chromosome
numbers occur. Species have highly localised distributions and are generally poor
dispersers, making this also an interesting group for historical biogeographic
reconstruction. Currently, AFLP markers are being generated for use in phylogenetic
reconstruction within the Hoarea clade which will enable mapping of trends in
morphological evolution as well as addressing questions relating to pollination biology,
karyology and biogeography.