Genetic Variation Patterns of "Algarrobos" from the "Great American Chaco" (Prosopis alba, P. nigra, P. hassleri, P. fiebrigii, P. ruscifolia, P. chilensis, and P. flexuosa)

Abstract

The "algarrobos complex of species" (Prosopis spp.) has its center of diversity in the "Gran Chaco Americano." Hybrid swarms and a continuum of morphological and genetic variation difficult the taxonomic identification as well as the definition of conservation and management units. Therefore, the development and use of morphological markers in leaves and fruits helped in species delimitation. In addition, the genetic characterization through neutral markers (isozymes, microsatellites) with the existence of species-specific alleles provided further insights. Natural interspecific hybridization processes were evaluated through morphological traits and molecular markers. Discrimination of species, morpho-groups within species and interspecific hybrids is presented in this chapter. Phylogeny and phylogeography of the genus through maternally inherited markers (noncoding sequences of chloroplasts) showed the underlying historical process shaping the disjunct distribution of some species. For evaluating adaptation, genetic characterization through the analysis of variation in quantitative traits is also presented. Finally, estimations of mating system parameters and pollen dispersal as well as spatial genetic structure provide information on the reproductive biology and migration abilities of the species.