Effect of population size on genetic variation levels in Capparis spinosa (Capparaceae) detected by RAPDs

Abstract

Background: The population size of plants affects on population genetic variation. Materials and Methods: We studied the impact of population size on genetic variation in populations of Capparis spinosa (caper, Capparaceae) using RAPDs in East Azerbaijan (Iran). Withinpopulation genetic diversity was estimated based on Nei's and Shannon's diversity using Popgen, and genetic similarity among the populations was studied from a UPGMA dendrogram based the matrix of Nei's distances obtained through SHAN. Difference in the level genetic variation between small-sized and large-sized populations was tested using Mann-Whitney U test, and correlation between geographical and genetic distances among populations was examined by Pearson test (SPSS, 11.3). Total genetic variation was partitioned into within and among populations based on AMOVA using Arlequin. Results: The polymorphism levels of RAPDs bands among the populations ranged from 48.8% to 81.4%, and within-population Nei's diversity varied from 0.1667 to 0.2630. Genetic variation in smallsized populations (0.1667 to 0.1809) was significantly lower than the variations in large-sized populations (0.2158 -0.2630) (N= 7, P 0.674, Pearson correlation test). Conclusions: Population size has a dramatic impact on its genetic diversity. The results revealed that fragmentation of caper population in the study region has most likely occurred recently. The low genetic diversity revealed within caper populations indicates high risk of extinction and suggests that urgent conservation action is needed to recover diversity in these populations.