Abstract
Maire yew (Taxus wallichiana var. mairei (Lemée H. Léveillé.) L. K. Fu et Nan Li) is a rare and endangered tree species, and it is also a precious timber species in China. We used 13 microsatellites to assess the genetic diversity and differentiation of 665 Maire yew samples from 18 natural populations. A total of 291 alleles were detected. The average number of alleles (Na=22.39), expected heterozygosity (He=0.74), polymorphic information content (PIC = 0.86) and Shannon diversity index (I = 1.66) of the loci indicated a high level of genetic diversity in natural Maire yew populations. Moreover, gene flow was more active among populations (Nm=1.62) than within populations. Among the 18 populations, the Xinfeng population in Jiangxi Province has the highest genetic diversity. Although each of the studied populations should be protected from further deforestation and agricultural expansion, the Xinfeng population deserves the highest conservation priority. The results based on analysis of molecular variance showed that genetic variation occurred mainly within populations (84.90%; P < 0.001), which indicated that the degree of genetic differentiation of the natural populations of Maire yew was low. Based on UPGMA, the 18 populations were categorized into 4 groups. A Mantel test showed that there was no significant correlation between standard genetic distance and geographical distance or altitude differences among the populations. The genetic clustering results also indicated that the genetic relationship followed a north to south clustered trend. The information presented here forms the basis for the development of genetic guidelines for appropriate conservation programs.
Genetic diversity of natural populations of Taxus wallichiana var. mairei