MOLECULAR PHYLOGENY OF THE GENUS SALIX (SALICACEAE) WITH AN EMPHASIZE TO ITS SPECIES IN IRAN

This study represents phylogenetic analyses of nrdna its for 62 accessions of 55 salix species and two populus species as outgroups using maximum parsimony and bayesian methods. a subset of 14 species of salix sampled for nrdna its was included in a phylogenetic analysis using trnl-f region. the resulting nrdna its phylogeny revealed that all five currently recognized salix subgenera except the monotypic subgenus longifoliae are not monophyletic. likewise, most of salix sections are not monophyletic. the analysis showed that salix humboldtiana, native to south america and mexico, positioned at the base of the tree as sister to the remaining salix species. the iranian salix species are scattered across the tree. several polymorphic nucleotide sites of nrdna its were detected for salix zygostemon, s. acmophylla and s. elymaitica. this indicates that these taxa may have a hybrid origin. in the case of salix zygostemon, trnl-f data showed that it was nested a polytomy containing s. cinerea and s. elbursensis. while on the nrdna tree, its position is unclear. meanwhile, the data suggested that salix may have been originated in warm temperate regions of the new world and then diversified in both warm and cold temperate regions of northern hemisphere.