Molecular phylogeny and phylogeography of Lupinus (Leguminosae) inferred from nucleotide sequences of the rbcL gene and ITS 1+2 regions of rDNA

Total DNA was extracted from 55 species of the Leguminosae (including 29 species of Lupinus). The chloroplast gene rbcL and the ITS 1 + 2 regions of nuclear RNA genes were amplified by polymerase chain reaction (PCR) and sequenced directly. The sequences obtained were evaluated with character state (Maximum Parsimony) and distance methods (Neighbour Joining). Phylogenetic trees obtained with both data sets and methods are mostly congruent. Genisteae and Crotalarieae are sister groups and share ancestry with the Thermopsideae/Podalyrieae. The genus Lupinus, which forms a monophyletic clade within the Genisteae, shows a distinct Old-New World disjunction and appears to be divided into several more or less distinct groups: (1) The species from the eastern part of South America. (2) The homogeneous rough-seeded group (Scabrispermae) of the Old World species which is well distinguished from the smooth-seeded group (Malacospermae). (3) Within the rather heterogeneous smooth-seeded lupins a smaller subgroup with L. augustifolius, L. hispanicus and L. luteus is recognized. (4) Also separated are North American lupins and South American species with a western distribution. Genetic distances imply that the genus Lupinus evolved during the last 12-14 million years; ruling out the hypothesis that the present Old-New World disjunction can be interpreted as a result of the continental drift. The genetic data suggest an origin in the Old World and an independent colonisation of the Eastern parts of South America as opposed to North America and the Western parts of South America.