Revista Chilena de Historia Natural 79 (3): 389-404, 2006
RESEARCH ARTICLE
Evolution of the series Microphyllae (Adesmia, Fabaceae) in the
Andean Cordillera: a biogeographic approach
Microphyllae (subgenus Acanthadesmia) is the series of the
genus Adesmia with the largest number of described species, and its distribution includes most of the genus range. The
biogeographic evolutionary history of this series, as well as the genus, is unclear. Some hypotheses suggest that the development of
the Andes affected the evolution of the genus Adesmia, but there is no evidence about the processes (e.g., dispersal or
vicariance) involved. In this study we used a panbiogeographic approach, and based on the distribution of 22 species of this series we
carried out a track analysis and a parsimony analysis of endemicity (PAE). Distribution area of the series was divided in quadrats of 1°x
1°(Latitude x Longitude), and latitudinal and longitudinal belts of 1º. All the species presented a distribution associated with the Andes,
and most of them presented both latitudinally and longitudinally restricted distributions. Five generalized tracks and two nodes were
found. All tracks were longitudinally associated with the Andean range. Nodes could be associated with the South American Transition
Zone. PAE based on latitudinal belts split the total area in two sub-areas (north and south), where the limit between them is central
Chile (ca. 33°S). This division is characterized by the presence of A. miraflorensis in the northern zone, and A.
volckmannii in the southern zone. Our results suggest a recent differentiation within the series Microphyllae, which
may have resulted from isolation of populations along the Andes, i.e., vicariance events fragmented the distribution of species and
subsequently caused differentiation. It seems likely that this separation has occurred latitudinally, as suggested by the latitudinal
sequence of generalized tracks.
Key words:
panbiogeography, track
analysis, Andes, Adesmia, PAE
