Genetic variation within and among three invasive Prosopis juliflora (Leguminosae) populations in the River Nile State, Sudan

Abstract

The species of Prosopis (Leguminosae) are trees or shrubs well adapted to grow in arid and semi arid regions. In Sudan Prosopis juliflora was introduced in 1917. Currently, it has become a noxious weed spreading aggressively in natural and managed habitats. The structure of genetic diversity within and among P. juliflora populations infesting three forests in the River Nile State were assessed by RAPD technique. A total of 56 bands were obtained from seven primers. The mean percentage of polymorphic loci over all populations was (55.36%). Kulhuda population had the highest percentage of polymorphic loci (64.29%) and the highest number of private alleles (3). Makabrab population had the lowest percentage of polymorphic loci (46.43%) and two private alleles. Mean expected heterozygosity was (0.218). High genetic differentiation was found among populations (PhiPT = 0.328, P = 0.001). There was a genetic variation of 33% among the populations and within them 67% (AMOVA, P < 0.001). The mean Shannon information index was (I = 0.319, SE = 0.023). UPGMA clustering did not precisely reflect the geographic position of the populations. The results show the current structure of the populations and the similarities between groups of populations, might be due to the recent introduction of the species into Sudan, the limited seed source, the extensive endozoic dispersal seed system and limited pollen dispersal. Key words: Prosopis juliflora, invasive, genetic variation, RAPD, Sudan.