Systematics and Evolution Group, Section of Natural History, Museum of Natural History and Archaeology, Norwegian University of Science and Technology, Trondheim, Norway.
Am J Bot. 2012 Apr;99(4):677-89. doi: 10.3732/ajb.1100410. Epub 2012 Apr 2.
Organisms may survive unfavorable conditions either by moving to more favorable areas by means of dispersal or by adapting to stressful environments. Pleistocene glacial periods represent extremely unfavorable conditions for the majority of life forms, especially sessile organisms. Many studies have revealed placements of refugial areas and postglacial colonization patterns of seed plants, but little is still known about areas of long-term survival and historical migration routes of bryophytes. Given overall differences in stress tolerance between seed plants and bryophytes, it is of interest to know whether bryophytes have survived periods of extreme climatic conditions better then seed plants in northern areas.
The haploid and rarely spore-producing peat moss Sphagnum wulfianum is mostly found in areas that were covered by ice during the last glacial maximum. Twelve microsatellite markers were amplified from 43 populations (367 shoots) of this species, and data were analyzed using population genetic diversity statistics, Bayesian clustering methods, and coalescence-based inference tools to estimate historical and demographic parameters.
Genetic diversity within populations was low, but populations were highly differentiated, with two main genetic clusters being recognized.
The two main genetic groups have diverged quite recently in the Holocene, and the pattern of genetic variability and structuring gives no support for survival in Scandinavian refugia during the last glacial period in this species. The dispersal ability of this plant thus seems surprisingly high despite its infrequent spore production.
生物可以通过扩散迁移到更有利的区域，或者通过适应压力环境来生存于不利条件下。更新世冰川期对大多数生命形式来说是极其不利的条件，尤其是固着生物。许多研究揭示了避难所区域的位置和种子植物的冰川后殖民化模式，但对于苔藓植物的长期生存区域和历史迁移路线仍然知之甚少。鉴于种子植物和苔藓植物在耐受压力方面的总体差异，了解在北方地区，苔藓植物是否比种子植物更好地度过了极端气候条件的时期，这是很有趣的。
在末次冰盛期，单倍体且很少产生孢子的泥炭藓 Sphagnum wulfianum 主要分布在被冰覆盖的地区。从该物种的 43 个种群（367 个芽）中扩增了 12 个微卫星标记，并使用种群遗传多样性统计、贝叶斯聚类方法和基于合并的推断工具分析数据，以估计历史和人口统计学参数。
种群内的遗传多样性较低，但种群高度分化，识别出两个主要的遗传群。
这两个主要的遗传群体在全新世最近才分化出来，遗传变异和结构的模式不支持该物种在末次冰期在斯堪的纳维亚避难所中的生存。尽管这种植物的孢子产生频率较低，但它的扩散能力似乎令人惊讶地高。
