Systematics and Evolution of Polyploid Mosses

最近Drs。怀亚特和斯通伯恩提供了第一个分子证据，证明一种天然苔藓的可能杂交起源，即中等苔藓。利用同工酶分析的方法，广泛应用于开花植物的研究，但直到最近才适用于苔藓，这些科学家发现苔藓中的蛋白质组成反映了美国北部两种假定的亲本物种的附加成分。这种杂交后代的染色体数量是双亲的两倍，并且是完全可育的。这种通过杂交和染色体加倍的物种形成机制已经在开花植物中得到了充分的记录，但迄今为止还没有在苔藓中得到证实。Drs。怀亚特和斯通伯恩将继续对这些苔藓物种的更多种群进行取样，并将该项目扩展到分析其他假定病例，其中已知的染色体计数表明可能是杂交起源。在实验室里，研究人员将尝试使假定的亲本杂交，以便在实验中复制杂交物种。尽管以单倍体生命周期为主导的苔藓在基本生物学上存在差异，但这项新研究表明，所有其他陆地植物的进化机制具有基本的相似性。

Recently Drs. Wyatt and Stoneburner have provided the first molecular evidence for the probable hybrid origin of a natural species of moss, Plagiomnium medium. Using methods of isozyme analysis, widely employed in studies of flowering plants but only recently adapted to mosses, these scientists found protein composition in the moss to reflect additive components of two presumed parental species in the northern United States. The hybrid has double the number of chromosomes found in the two parents, and is fully fertile. This mechanism of species formation, by hybridization followed by chromosome doubling, has been amply documented in flowering plants, but not in mosses heretofore. Drs. Wyatt and Stoneburner will continue to sample more populations of these moss species and will extend the project to analyses of additional presumptive cases, where known chromosome counts suggest a probable hybrid origin. In the laboratory the investigators will attempt to cross-fertilize the presumptive parents in order to duplicate experimentally the hybrid species. Despite differences in the basic biology of mosses, with their dominant haploid life-cycle, this new work demonstrates fundamental similarity in a mechanism of evolution operating in all other land plants.