Abstract
Capparis decidua is a rangeland plant species growing in isolated populations in Saudi Arabia. Genetic diversity within and among six populations (Madina, Farasan island, Hawayer Assos, Khor Assos, Raudhat Khuraim, and Taif) of C. decidua was studied using RAPD technique. Of the 25 random primers were used, eighteen (18) primers generated discernible and reproducible bands. A total of 152 reproducible RAPD bands across the 36 individuals were amplified. Out of those, 117 (76.2%) RAPD bands were polymorphic. The number of polymorphic bands per primer ranged between 3 and 11 with an average of 6.5 bands per primer. Populations differed in the level of genetic diversity as shown from the percentage of polymorphic bands. Farasan population had the highest level of genetic diversity (24.3%) and two populations Khor Assos (5.9%) and Taif (4.6%) had the lowest genetic diversity. Analysis of molecular variance (AMOVA) showed highly significant differences among populations. Among the population variance accounted, there is a higher percentage of the total variance (average 77.67%, SD +/- 8.21) than within populations (average 22.33%, SD +/- 8.21). There is no significant correlation between geographical distance and genetic distance was found. However, there was a significant positive correlation between molecular genetic variation and actual population size. The implication of the results of this study in devising strategy for conservation of C. decidua is discussed.