Resumo

SAIDMAN, Beatriz O. et al. Evolutive and poblational studies in the genus Prosopis using biochemical and molecular markers . Multequina [online]. 2000, vol.9, n.2, pp.81-93. ISSN 1852-7329.

The way in which genetic variability is distributed within and among populations depends on different factors, outstanding among these are the reproductive system and the adaptive strategy. Population structure, in turn, imposses restrictions to those evolutionary processes tending to a growing adaptation to the environment and/or specific differentiation. Studies on population structure were made for the Prosopis genus and the genetic differentiation was analyzed for 15 species of Algarobia, Strombocarpa and Monilicarpa Sections using isoenzyme techniques, RAPD, RFLP and DNA sequenciation. The linkage system was analyzed in 7 species of the Algarobia Section from data obtained from isoenzyme electrophoresis, which showed that although these species are mostly exogamous they can reach up to 28% of self-fecundation, with an average of 19%. This behaviour and the limited capacity for pollen and seed dispersal determine an excess of homozygotes in the populations. Except for P. kuntzei, Algarobia species are closely related, independently of their ploidy level and geographical distribution, and are not grouped according to series. Species in the Strombocarpa Section exhibit much lower variability than those in Algarobia. P. argentina (Monilicarpa Section) is the most distinctly differentiated of the species studied to date. Natural hybridation is frequent among species of the Algarobia Section. This phenomenon and the great similarity among these species make their recognition difficult. The results obtained using RFLP techniques in mitocondria and cloroplasts confirm the great affinity among Algarobia species, and provide evidence that they would have a common origin.

Palavras-chave : Isoenzymes; RADP; DNA sequenciation; Population structure.

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