CAUJAPE-CASTELLS1,2, JULI*, ROBERT K. JANSEN2, JOAN PEDROLA-MONFORT1, AND NURIA MEMBRIVES1. 1: Estacio Internacional de Biologia Mediterrania-Jardi Botanic Marimurtra. Psg. Karl Faust 10, 17300 Blanes, Girona (Spain)., 2: The Department of Botany. The University of Texas at Austin. Austin, Texas 78713-7640. - Dissecting an African disjunction: molecular phylogeny of the genus Androcymbium Willdenow (Colchicaceae).
The absence of a phylogenetic hypothesis in the genus
Androcymbium has prevented the examination of at least two
major evolutionary topics. One of them has to do with the origin and
dynamics of the geographical disjunction between North and South
Africa. The other concerns the identification of the continental
relatives of the two species from the Canary Islands. We generated a
cpDNA phylogeny through the examination of restriction site variation
for 21 endonucleases in 53 populations of the genus. Our sampling
includes all known stands of the six species in North Africa and the
Canary Islands, plus a thorough populational representation of the
taxa in the Atlantic fringe and the Western mainland of Southern
Africa. A total of 857 mutations were detected, 567 of which were
phylogenetically informative. Our analyses strongly support a South
African origin of the genus with A. eucomoides from the
Mediterranean region of the Cape province sister to the monophyletic
North African group. The close relationship between the North African
A. wyssianum and the two Canarian species A.
psammophilum and A. hierrense is in agreement with previous
allozymic evidence. South African taxa occur in three well-supported
paraphyletic groups with different rates of cpDNA evolution both
within and between them. This raises the issue of how the substantial
ecobiological differences among the two main geographical zones of
distribution might have affected the evolutionary dynamics of the
genus.
Key words: Africa, Androcymbium, Biogeography, Colchicaceae, Phylogeny, RFLPs