Inter- and intra-genetic variation of four wild populations of Prosopis using rapd-pcr fingerprints

The species of Prosopis (Leguminosae) are well adapted to grow in the arid regions of the world. In Mexico, nearly 70% of its territory accounts for arid lands and nine species of this genus are found in the country which are currently utilized for multiple purposes. Given that a sustainable exploitation of this important natural resource is necessary, knowledge of the genetic variability of natural populations is required. The genetic variation among and within four wild populations of Prosopis glandulosa, P. juliflora, and two of P. laevigata, located in the Mexican States of Chihuahua (1), Sinaloa (2), Guanajuato (3) and Hidalgo (4), respectively, was determined using random amplified polymorphic DNA (RAPDs). There was a genetic variation of 72.48% among these four populations, and within them the estimated genetic variation was 27.52%. Between the populations of P. laevigata the genetic variation obtained was 7.15%, and within them 92.85% (AMOVA, P < 0.001). Based on the assumption of Wright's island model, the genetic variation found among populations corresponds to a gene flow (N(e)m) of 0.09, while the gene flow detected between the populations of P. laevigata was 3.2. A total of 27 RAPD phenotypes were identified in the four populations; among them, 11 corresponded to P. laevigata. The phylogenetic analyses showed that the three species are differentiated in three clades and that probably P. juliflora was the origin of the other two species. The protogynous trait of their flowers and the outcrossing are the main factors that may explain the genetic variation observed in these populations.