Pfanzelt Simon, Albach Dirk C, von Hagen Klaus Bernhard
Institute of Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.
Mol Ecol. 2017 Aug;26(15):4027-4044. doi: 10.1111/mec.14156. Epub 2017 May 30.
The extent of the Pleistocene glaciations in the Patagonian Channel region (southwesternmost South America) and their impact on the vegetation there are largely unknown. Whether the regional flora was wiped out completely (tabula rasa) or survived in ice-free pockets (in situ survival) is still an open question. The molecular imprint of either scenario should still be visible in extant populations. Therefore, DNA sequence data of Oreobolus obtusangulus Gaudich. (Cyperaceae) were analysed. This species is an abundant constituent of Patagonian cushion peat bogs, one of the Patagonian Channel region's major vegetation types. Three hundred and eighty-four individuals from 48 populations were sequenced for two chloroplast (ycf3-psaA and trnQ -psbK intergenic spacers) and 14 nuclear loci containing simple sequence repeats (SSRs; microsatellites). Phylogenetic reconstructions and the geographic distribution of genetic diversity revealed that the species was split into three main lineages whose general distributions comprise three separate major regions, that is, south-central Chile, Fuego-Patagonia and the East Patagonian Andes, which probably constitute glacial refugia. Postglacial migration fronts formed a suture zone with high levels of genetic diversity in the Northwest Patagonian Andes, where remnants of a supposedly ancestral lineage were also found to be locally restricted to a single population (Huinay). The heavily glaciated Patagonian Channels were likely recolonized from the northwest, and partly from the south. Although the westernmost Patagonian Channel population (Estero Bachem) harboured private SSR alleles (singletons) and showed slightly elevated genetic diversity, it remained unclear whether this population actually survived in situ. This study helps fill a major gap in reconstructing the Pleistocene vegetation history of West and Andean Patagonia.
巴塔哥尼亚海峡地区（南美洲最西南部）更新世冰川作用的范围及其对当地植被的影响在很大程度上尚不明确。该地区的植物群是被彻底消灭（白板状态）还是在无冰区域存活下来（原地存活）仍是一个悬而未决的问题。这两种情况的分子印记在现存种群中应该仍然可见。因此，对钝叶山姜（莎草科）的DNA序列数据进行了分析。该物种是巴塔哥尼亚垫状泥炭沼泽的主要组成部分，而巴塔哥尼亚垫状泥炭沼泽是巴塔哥尼亚海峡地区主要的植被类型之一。对来自48个种群的384个个体进行了两个叶绿体基因（ycf3 - psaA和trnQ - psbK基因间隔区）以及14个含有简单序列重复序列（SSRs；微卫星）的核基因座的测序。系统发育重建和遗传多样性的地理分布表明，该物种被分为三个主要谱系，其总体分布包括三个独立主要区域，即智利中南部、火地岛 - 巴塔哥尼亚以及巴塔哥尼亚安第斯山脉东部，这些区域可能构成了冰川避难所。冰期后的迁移前沿在巴塔哥尼亚安第斯山脉西北部形成了一个具有高遗传多样性的缝合带，在那里还发现一个推测的祖先谱系的残余部分在当地仅局限于一个种群（韦纳伊）。冰川作用强烈的巴塔哥尼亚海峡很可能是从西北方向重新定殖的，部分是从南方。尽管最西部的巴塔哥尼亚海峡种群（巴切姆河口）拥有私有SSR等位基因（单例）且遗传多样性略有升高，但尚不清楚该种群是否真的原地存活。这项研究有助于填补重建巴塔哥尼亚西部和安第斯地区更新世植被历史方面的一个主要空白。
