Plant and Microbial Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
Am J Bot. 2004 Jan;91(1):73-85. doi: 10.3732/ajb.91.1.73.
The European hawkweed Hieracium pilosella is a successful invader and a troublesome weed in New Zealand. The systematics of the genus Hieracium is extremely complex and contentious, probably due to recent speciation, hybridization, polyploidy, and diverse reproductive strategies. In the first chloroplast DNA survey of the group, we sequenced 285 plants (including H. pilosella and 12 other species of subgenus Pilosella) from New Zealand and Europe for 900 bp of trnL-trnF. Eleven haplotypes were identified with much sharing among species. Three haplotypes (A, D, G) were found in seven, three, and four species, respectively, but two species (H. lactucella and H. auricula) had single, private haplotypes. Our cpDNA data for subgenus Pilosella are consistent with the group's having incomplete lineage sorting and/or recent reticulate evolution. Six haplotypes were identified in H. pilosella, four of these unique to this taxon in our sample. In New Zealand, haplotype A was common and occurred in plants of different ploidy (i.e., 4×, 5×, 6×), whereas haplotypes C, B, and M were restricted to 4×, 5×, and 6× plants, respectively. The distribution of haplotype variation suggests that some or all of the H. pilosella seeds accidentally introduced into New Zealand probably came from east Europe rather than the United Kingdom and that a minimum of four lineages were introduced. Within New Zealand, hybridization of H. pilosella with a related taxon (probably H. praealtum) has occurred at least three times, involving both obligate sexual tetraploids and facultative apomictic pentaploids of H. pilosella.
欧洲千里光 Hieracium pilosella 是一种成功的入侵物种，也是新西兰令人头疼的杂草。该属的系统发育极其复杂和有争议，可能是由于最近的物种形成、杂交、多倍体和多样化的繁殖策略。在对该组的第一次叶绿体 DNA 调查中，我们对来自新西兰和欧洲的 285 株植物（包括 H. pilosella 和亚属 Pilosella 的 12 个其他物种）进行了测序，测序长度为 900 bp 的 trnL-trnF。鉴定出 11 种单倍型，物种之间有很多共享。在 7、3 和 4 个物种中分别发现了 3 个单倍型（A、D、G），但 2 个物种（H. lactucella 和 H. auricula）具有单一的、独特的单倍型。我们对亚属 Pilosella 的 cpDNA 数据与该组不完全谱系排序和/或最近的网状进化一致。在 H. pilosella 中鉴定出 6 种单倍型，其中 4 种在我们的样本中是该分类群所特有的。在新西兰，A 单倍型很常见，存在于不同倍性（即 4×、5×、6×）的植物中，而 C、B 和 M 单倍型分别局限于 4×、5×和 6×植物中。单倍型变异的分布表明，偶然引入新西兰的一些或全部 H. pilosella 种子可能来自东欧而不是英国，至少有 4 个谱系被引入。在新西兰，H. pilosella 与一个相关分类群（可能是 H. praealtum）发生了至少 3 次杂交，涉及到 H. pilosella 的强制性有性四倍体和兼性无融合生殖的五倍体。
