Chapman H M, Parh D, Oraguzie N
Department of Plant and Microbial Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
Heredity (Edinb). 2000 Apr;84 ( Pt 4):401-9. doi: 10.1046/j.1365-2540.2000.00657.x.
Introduced populations of weeds which are polyploid and reproduce primarily by apomixis are generally considered as having low levels of population genetic variation, highly differentiated populations and short evolutionary lifespans. Although polyploidy allows for habitat differentiation and colonization, lack of recombination because of apomixis means that long-term persistence is unlikely. However, variation can be introduced to a colonizing population by evolutionary changes in the mating system, or by somatic mutation and recombination. In this study hypersensitive genetic markers, inter-simple sequence repeats (ISSRs), were used to quantify genetic variation within Pilosella officinarum, a major weed of the New Zealand high country. Pilosella officinarum was introduced from Europe to New Zealand late in the 19th century and only polyploid, apomictic populations are thought to have survived. The combination of introduction history and breeding system has led to the assumption that New Zealand populations are necessarily genetically depauperate. However, our studies reveal variable levels of genetic variation and patterns of clonal distribution which indicate varying levels of sexual reproduction within New Zealand populations.
多倍体且主要通过无融合生殖进行繁殖的外来杂草种群通常被认为种群遗传变异水平较低、种群高度分化且进化寿命较短。尽管多倍体能够实现栖息地分化和定殖，但由于无融合生殖导致的缺乏重组意味着其长期存续的可能性不大。然而，交配系统的进化变化、体细胞突变和重组能够为定殖种群引入变异。在本研究中，超敏感遗传标记——简单序列重复区间（ISSR），被用于量化新西兰高地的一种主要杂草——药用毛连菜（Pilosella officinarum）的遗传变异。药用毛连菜于19世纪末从欧洲引入新西兰，据信只有多倍体、无融合生殖种群存活了下来。引入历史和繁殖系统的结合导致人们认为新西兰的种群必然在遗传上匮乏。然而，我们的研究揭示了不同水平的遗传变异和克隆分布模式，这表明新西兰种群内存在不同水平的有性生殖。
