Exploring morphological evolution in relation to habitat moisture in the moss genus Fissidens using molecular data generated from herbarium specimens

Morphological evolution in mosses has long been hypothesized to accompany shifts in microhabitats, which can be tested using comparative phylogenetics. These lines of inquiry have been developed to include target capture sequencing, which can yield phylogenomic scale data from herbarium specimens. Here, we test the relationship between taxonomically important morphological characters in the moss genus Fissidens, using a 400-locus data set generated using a target-capture approach in tandem with a three-locus phylogeny generated using Sanger sequencing. Phylogenetic trees generated using ASTRAL and Bayesian inference were used to test the monophyly of subgenera/sections. These trees provide the basis for ancestral character state reconstructions and phylogenetic correlation analyses for five morphological characters and characters related to the moisture habitat, scored from the literature and by specimen inspection. Many of these characters exhibit statistically significant phylogenetic signal. Significant correlations were found between the limbidium (phyllid/leaf border of the gametophyte) and habitat moisture niche breadth, which could be interpreted as the more extensive limbidium enabling species to survive across a wider variety of habitats. We also found correlations between costa anatomy, peristome morphology, and the limbidium, which could reflect the evolutionary recruitment of genetic networks from the gametophyte to the sporophyte phase. The correlation found between average habitat moisture and the sexual system indicates that dioicous and polyoicous species are more likely to be found in moist habitats and that these higher moisture levels could be particularly, reproductively advantageous to species with separate sexes.     

冰缘区藓类植物叶中肋细胞生态适应性分析

对采自新疆天山一号冰川冰缘区的35种生长在不同生境的藓类植物，分别观察离析后其叶片的中肋导水细胞长、宽，细胞壁厚薄、细胞端尾和纹孔场的数目。湿土面、阴湿岩面、土面和岩面四种生境下的藓类植物叶中肋细胞，随着生境中水分条件由湿到干其细胞长度、细胞宽度和厚度均有变大的趋势；中肋细胞端尾的形式多样，生长在土面的藓类具有多个端尾，具有增强细胞间的联系，有效控制导水和物质交换速度，并提高机械固着和支撑作用。不同生境下叶中肋细胞侧壁的纹孔场数目并无明显差异。中肋细胞的特征反映出其对冰缘区极端而复杂的环境的适应策略，为进一步研究苔藓植物在高寒环境地区的导水机理及生态适应性提供了一定的参考依据。