Adaptive genetic diversity and population structure of the “algarrobo” [Prosopis chilensis (Molina) Stuntz] analysed by RAPD and isozyme markers

Abstract

The ''algarrobo'' [Prosopis chilensis (Molina) Stuntz] is a tree species that represents an important natural resource in arid and semi-arid regions of Argentina. In this paper, we analysed and compared the variability of 46 RAPD (Random Amplified Polymorphic DNA) loci with previous estimates obtained from 12 isozyme markers in nine Argentinean populations of P. chilensis representative of the whole range of this species in Argentina. We evaluated the population structure and the existence of genetic variants associated with environmental variables. Expected heterozygosity (H e ) estimated from RAPD varied significantly among populations and regions. Hierarchical analysis of genetic variability (AMOVA) showed that most (88.1%) of the total diversity occurs within populations, the component among populations within regions (9.3%) was intermediate, while the between-region component was the lowest (2.6%). All three variance components were highly significant. The MDS plot from pair-wise U ST matrix was consistent with the highly significant among-region differentiation indicated by the AMOVA. All 12 variable isozyme loci and 26 out of 46 RAPD loci showed significant or highly significant association with at least one geographic/climatic variable according to the stepwise multiple regression analysis. These results imply that the genetic differentiation among populations is better explained by environmental or biogeographical grounds than by geographical distances, suggesting gametic disequilibrium with loci responsible for the adaptation to particular environmental conditions. The information from RAPD markers would provide a relevant criterion to preserve genetic diversity in programmes for conservation and rationale use of this species. Communicated by R. Matyssek. Electronic supplementary materialThe online version of this article (

Evidences of local adaptation in quantitative traits in Prosopis alba (Leguminosae)

“…Although livestock are able to disperse seeds over larger distances (up to 4-6 km) in comparison with small rodents (approximately 50 m; Reynolds 1954, Keys 1993Keys and Smith 1994), in all cases herbivorous tend to eat as many pods as they can from each single tree, and scarified seeds after passing through the animal gut are deposited in dungs forming groups of related individuals (Keys 1993;Bessega et al 2000). Moreover, previous works on natural populations of P. alba geographically distant (Ferreyra et al 2004(Ferreyra et al , 2007(Ferreyra et al , 2010 have also shown that most genetic variation occurs within populations and that the differentiation among populations and regions for molecular markers is rather low. The ability to maintain high genetic coherence in spite of limited dispersal ability may be associated with the long life span of Prosopis species together with original large populations' sizes and continuous distribution that characterized forests in the Chaqueña Region before the habitat fragmentation produced by human activities.…”

Morphometric and phytochemical characterization of chaura fruits (Gaultheria pumila): a native Chilean berry with commercial potential

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