XVI International Botanical Congess

Alonsoa is an amphi-Atlantic disjunct with centers of diversity in South America and South Africa. Previous studies have failed to resolve where the genus originated and whether the specialized pollination system of the African taxa is plesiomorphic or apomorphic. A phylogeny based on ITS sequences is presented for Alonsoa and selected outgroups. This phylogeny indicates that Alonsoa originated in South Africa, even though the genus is more speciose in South America. The specialized oil flower/oil bee syndrome evolved prior to the origin of Alonsoa, and was secondarily lost in South America. After an initial phase of pollination by generalist pollen collectors and predominate selfing, South American species embarked on a secondary path of evolutionary specialization involving buzz pollination and predominant outcrossing.