M Pedersen A Tiril, Nowak Michael D, Brysting Anne K, Elven Reidar, Bjorå Charlotte S
Natural History Museum, University of Oslo, Oslo, Norway.
Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway.
PLoS One. 2016 Oct 25;11(10):e0165430. doi: 10.1371/journal.pone.0165430. eCollection 2016.
Hybridization is frequent in the large and ecologically significant genus Carex (Cyperaceae). In four important sections of the northern regions (Ceratocystis, Glareosae, Phacocystis and Vesicariae), the frequent occurrence of hybrids often renders the identification of "pure" species and hybrids difficult. In this study we address the origins and taxonomic rank of two taxa of section Vesicariae: Carex rostrata var. borealis and C. stenolepis. The origin and taxonomic status of C. stenolepis has been the subject of substantial debate over the years, whereas C. rostrata var. borealis has received very little attention in the years since its first description in the 19th century. By performing an extensive sampling of relevant taxa from a broad distribution range, and analyzing data from fifteen microsatellite loci developed specifically for our study together with pollen stainability measures, we resolve the hybrid origins of C. rostrata var. borealis and C. stenolepis and provide new insights into this taxonomically challenging group of sedges. Our results are in accordance with previous findings suggesting that C. stenolepis is a hybrid between C. vesicaria and C. saxatilis. They are also in accordance with a previous proposition that C. rostrata var. borealis is a hybrid between C. rostrata and C. rotundata, and furthermore suggest that both hybrids are the result of multiple, recent (i.e., postglacial) hybridization events. We found little evidence for successful sexual reproduction within C. rostrata var. borealis and C. stenolepis, but conclude that the common and recurrent, largely predictable occurrence of these taxa justifies accepting both hybrids as hybrid species with binomial names. There are, however, complications as to types and priority names, and we therefore choose to address these problems in a separate paper.
杂交现象在莎草科苔草属这个大型且具有重要生态意义的属中很常见。在北方地区的四个重要组（角苔草组、糙果苔草组、肿苞苔草组和囊苔草组）中，杂种的频繁出现常常使得“纯”物种和杂种的鉴定变得困难。在本研究中，我们探讨了囊苔草组的两个分类单元的起源和分类等级：北苔草（Carex rostrata var. borealis）和窄鳞苔草（C. stenolepis）。多年来，窄鳞苔草的起源和分类地位一直是大量争论的主题，而自19世纪首次描述以来，北苔草在这些年里很少受到关注。通过对广泛分布范围内的相关分类单元进行广泛采样，并分析专门为我们的研究开发的15个微卫星位点的数据以及花粉可染性测量结果，我们确定了北苔草和窄鳞苔草的杂交起源，并为这一分类学上具有挑战性的莎草类群提供了新的见解。我们的结果与之前的研究结果一致，表明窄鳞苔草是囊苔草（C. vesicaria）和岩生苔草（C. saxatilis）之间的杂种。它们也与之前的一个观点一致，即北苔草是喙苔草（C. rostrata）和圆囊苔草（C. rotundata）之间的杂种，并且进一步表明这两个杂种都是多次近期（即冰期后）杂交事件的结果。我们几乎没有发现北苔草和窄鳞苔草有成功有性繁殖的证据，但得出结论，这些分类单元常见且反复出现、在很大程度上可预测的出现情况证明将这两个杂种都接受为具有双名的杂交物种是合理的。然而，在类型和优先名称方面存在复杂情况，因此我们选择在另一篇论文中解决这些问题。
