Genetic diversity and differentiation of Michelia maudiae (Magnoliaceae) revealed by nuclear and chloroplast microsatellite markers

Michelia maudiae Dunn. is a Magnoliaceae species threatened by habitat destruction and over-exploitation. Genetic diversity and differentiation, population contribution to total diversity and allelic/haplotypic richness, and the relative importance of pollen- and seed-mediated gene flow were investigated in nine populations (192 individuals) of M. maudiae using nuclear and chloroplast microsatellites to further our understanding of the genetic structure and evolutionary history of this tree species and to provide a genetic perspective for its conservation. The species had strong pollen mediated gene flow in the past. The ratio of pollen to seed gene flow was 25.4. Three clusters from the western, central, and eastern China were identified by both chloroplast and nuclear microsatellites. Western populations at Xiaodanjiang and Daoxian were phylogenetically divergent from the remaining populations and might be particularly important for the conservation of this species. The populations of Xiaodanjiang, Daoxian, and Minjiangyuan made positive contribution to the total diversity and allelic/haplotypic richness, and were worthy of being conserved with priority. In the central cluster, population at Laopengding should be protected since it harbored the greatest genetic diversity.