Evolución de la serie Mycrophyllae (Adesmia, Fabaceae) en la Cordillera de los Andes: Una perspectiva biogeográfica

Abstract

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 degrees x 1 degrees (Latitude x Longitude), and latitudinal and longitudinal belts of 1 degrees. 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 subareas (north and south), where the limit between them is central Chile (ca. 33 degrees 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 freom isolation of populations along the Andes, i.e., vicariance events freagmented 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.