Mating system parameters in species of genus Prosopis (Leguminosae)

The section Algarobia of genus Prosopis involves important natural resource s in arid and semiarid regions of the world. Their rationale use requires a better knowledge of their biology, genetics and mating system. There are c ontradictory information about their mating system. Some authors claim they are protogynous and obligate outcrosser. However, some evidence have been shown indicating that they might not be protogynous and that they might be somewhat self-fertile. The current paper analyses genetic structure and mat ing system parameters in populations of seven species of this section from South and North America based on isozyme data. In all species a significant homozygote excess was found in the offspring population but nor in mother plant genotypes. Multilocus and mean single locus outcrossing rates (tm. ts ) indicated that about 15 % selfing can occur in the studied populations. T he heterogeneity between pollen and ovule allele frequencies was low sugges ting population structuration, in agreement with the estimates of correlati on of tn? within progeny (rt) and correlation of outcrossed paternity (rp). The difference of F-IS estimates between offspring and mother plants sugge st some selection favouring heterozygotes between seedling and adult stages .