Abstract

We compared the genetic diversity estimated from allozymes and from random amplified polymorphic DNA (RAPDs) in a sample of seven Lavandula multifida L. populations from three bioclimates in Tunisia. Seven isozymes coding for 14 putative loci and 97 RAPD markers, amplified by seven decamer random primers, were used. A high genetic diversity within populations was detected both by isozymes (P =73.8%; Ap = 2.0 and He = 0.231) and RAPDs (61.86 < P < 80.41% and 0.308 < H <0.459). The populations from the lower semi-arid bioclimate showed relatively higher polymorphism. A high genetic differentiation among all populations and a limited gene flow at all space scales were detected as a result of habitat fragmentation, low size of populations and genetic drift. However, the level of differentiation among populations revealed by RAPDs (Ф_ST = 0.370; G_ST = 0.372) was higher than that of allozymes (F_ST = 0.244). The unweighted pair group method with arithmetic mean (UPGMA) dendrograms based on matrices of F_ST and Ð¤_ST were not concordant, and there is no significant correlation between the two data sets. The cluster from allozymes revealed higher separation among most populations. The dendrogram from RAPDs separated populations into three distinct subclusters. The groupings of populations in both dendrograms did not reflect spatial geographic or bioclimatic patterns, indicating particular adaptation of populations to local environments. The dendrogram, based on combined data had led to similar population groupings to that probed by RAPDs. The high differentiation among all populations implies that collection of seeds for ex situconservation should be done from all populations from all bioclimatic zones even at a low geographic distance.

Key words: Lavandula multifida, genetic diversity, population structure, isozymes,random amplified polymorphic DNA (RAPDs).