Phylogenetics of Bruguiera spp. from the west coast of Peninsular Malaysia with emphasis on the population genetic structure of Bruguiera gymnorrhiza

Despite being a key genus in mangrove ecosystems, genetic information on Bruguiera remains limited. This study investigated the phylogenetic relationships among Bruguiera species, their genetic diversity, and the population genetic structure of B. gymnorrhiza along the west coast of Peninsular Malaysia (WCPM). DNA sequences were generated from 58 trees representing B. gymnorrhiza , B. sexangula , B. hainesii , B. parviflora , and B. cylindrica collected from six mangrove forests in WCPM. Three genetic markers, nuclear cellulose synthase A ( CesA ), UNK gene ( UNK ), and chloroplast intergenic region ( trnS–trnG ), were analysed to construct phylogenies and infer phylogeographic patterns. The CesA phylogeny provided the highest resolution, identifying 30 Bruguiera haplotypes, some of which were shared between Malaysian populations of B. gymnorrhiza and those from Mozambique, Southeast Asia, India, and Japan. Bruguiera parviflora was sister taxon to all other sampled Bruguiera species. Monophyly was observed for B. parviflora and B. sexangula , whereas B. gymnorrhiza appeared polyphyletic. The close phylogenetic relationship of B. hainesii with B. gymnorrhiza and B. cylindrica supports its hybrid origin. Population genetic analyses revealed moderate nucleotide diversity ( π = 0.03675), low genetic differentiation (FST = 0.03582), no significant population structure, and high gene flow among populations.