Differences in spatial genetic structure and diversity in two mosses with different dispersal strategies in a fragmented landscape

The Thousand-Island Lake (Zhejiang Province, China) was artificially isolated 50 years ago and provides an interesting model for investigating the impact of fragmentation on the spatial genetic structure in plant populations. Using variation from inter-simple sequence repeat markers and DNA sequences in two moss species with contrasting reproductive strategies, Hypnum plumaeforme and Pogonatum inflexum, we investigate the effect of sexual and asexual reproduction on molecular diversity and spatial genetic structure in this fragmented landscape. In H. plumaeforme, which mostly reproduces asexually, genetic diversity of island populations was significantly higher than that of lakeside populations. In the frequently fertile P. inflexum, conversely, genetic diversity was not significantly different between island and lakeside populations. Furthermore, a clear island versus lakeshore structure emerged from the spatial analysis of genetic variation in H. plumaeforme, but not in P. inflexum. We conclude that differences in reproductive strategies have a substantial effect on spatial genetic structure. In addition, landscape fragmentation may lead to the exacerbation of genetic differentiation in species with limited dispersal abilities at this scale, causing substantial spatial genetic structure.