Extinction of biodiversity due to human activities is a severe global problem. In Europe, however, only a few plant species died out so far. We investigated a dubious, disregarded taxon—Saxifraga oppositifolia subsp. amphibia—which became extinct in the 1960s. It exclusively occurred in a specific niche, namely in seasonally flooded waterside bank vegetation around Lake Constance in Germany and Switzerland. It has either been interpreted as a glacial relict or as a recent dealpine taxon. Using herbarium material, we conducted phylogenetic analyses based on ITS and cpDNA sequence variation. The taxon shared a chloroplast haplotype of S. oppositifolia, which is mainly distributed in the Alps, favouring the dealpine hypothesis. Nuclear data revealed several paralogous copies nested inside S. oppositifolia, most of which, however, differed from other S. oppositifolia accessions including those from the vicinity of Lake Constance. The oldest mean stem node ages of these ITS copies date between 0.91 and 0.28 my. Contradicting cpDNA, this may indicate that this saxifrage was a distinct taxon and possibly a relict originating in Middle Pleistocene glaciations. If so, the present study exemplifies that arctic-alpine plants survived in specific niches at low altitudes during interglacials and that corresponding taxa with a limited distribution are especially prone to extinction.

中文翻译：

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灭绝的中欧地方性虎耳草亚种的分子分析。两栖动物及其对冰川生物地理学的影响

人类活动造成的生物多样性灭绝是一个严重的全球性问题。但是，在欧洲，到目前为止，只有极少数的植物物种灭绝。我们调查了一个可疑的，被忽视的分类单元-虎耳草亚种。两栖动物-在1960年代灭绝。它仅发生在特定的生态位中，即在德国和瑞士的博登湖周围季节性季节性泛滥的水岸植被中。它要么被解释为冰川遗迹，要么被解释为最近的松树生物分类单元。使用植物标本室材料，我们基于ITS和cpDNA序列变异进行了系统发育分析。该分类单元共有一个S的叶绿体单倍型。对生，主要分布在阿尔卑斯山，有利于脱松树假说。核数据揭示了嵌套在S内的数个旁系同源拷贝。相反，其中大多数与其他S不同。oppositifolia种质包括那些从康斯坦茨湖附近。这些ITS副本的最老平均茎节年龄在0.91至0.28 my之间。与cpDNA相反，这可能表明该虎耳草是一个独特的分类单元，可能是起源于中更新世冰川的遗迹。如果是这样，则本研究证明了北极高寒植物在间冰期之间在低海拔的特定生态位中生存，并且相应的分布有限的类群特别容易灭绝。