Genetic and morphological variation patterns of Macromitrium gymnostomum and their geographical backgrounds

Macromitrium gymnostomum Sull. & Lesq. is widely distributed in southeastern China, with high morphological variation and confusion with allied species. To correctly define the morphological variation range of M. gymnostomum and the relationship among morphological patterns, genetics, and geographical factors, 13 morphological traits based on 106 samples from 11 populations of M. gymnostomum were determined. The 106 samples were preliminarily clustered into eight groups based on the 13 morphological traits. Using 13 pairs of ISSR primers, 150 ISSR bands were amplified, of which 148 (98.67%) were polymorphic. The intra-population genetic diversity accounted for 62.22%, whereas the inter-population value accounted for 37.78%. Gene flow existed among populations, with a N_m index of 0.8235 and a G_st of 0.3778. The genetic distance among the 11 geographical populations varied from 0.0873 to 0.2363, with an average of 0.1508. Based on information from the 148 loci, the 106 samples were clustered into eight groups. The morphological variations of M. gymnostomum were genetically controlled to an extent (r=0.159, n=106, P < 0.2). Distinctive geographical influences on morphological (r=0.309, n=106, P < 0.01) and genetic differentiation (r=0.251, n=106, P < 0.01) were also found.