DNA sequence data have become a crucial tool in assessing the relationship between morphological variation and genetic and taxonomic groups, including in the Antarctic biota. Morphologically distinct populations of submersed aquatic vascular plants were observed on sub-Antarctic Marion Island, potentially representing the two species of such plants listed in the island's flora, Limosella australis R.Br. (Scrophulariaceae) and Ranunculus moseleyi Hook.f. (Ranunculaceae). To confirm their taxonomic identity, we sequenced a nuclear locus (internal transcribed spacer; ITS) and two plastid loci (trnL-trnF, rps16) from three specimens collected on Marion Island and compared the sequences with those in public sequence databases. For all three loci, sequences from the Marion Island specimens were nearly identical despite morphological dissimilarity, and phylogenetic analyses resolved them to a position in Limosella. In phylogenetic trees and comparisons of species-specific sequence polymorphisms, the Marion Island specimens were closest to a clade comprising Limosella aquatica L., L. curdieana F.Muell. and L. major Diels for ITS and closest to L. australis for the plastid loci. Cytonuclear discordance suggests a history of hybridization or introgression, which may have consequences for morphological variability and ecological adaptation.

中文翻译：

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亚南极马里恩岛水生植物 Limosella 杂交的分子证据

DNA 序列数据已成为评估形态变异与遗传和分类群之间关系的重要工具，包括在南极生物群中。在亚南极马里恩岛上观察到形态不同的沉水水生维管植物种群，可能代表岛上植物群中列出的两种此类植物，澳洲青柠R.Br. （玄参科）和毛茛Hook.f. （毛茛科）。为了确认它们的分类学特性，我们对一个核基因座（内部转录间隔区；ITS）和两个质体基因座（trnL-trnF,rps16）从马里恩岛收集的三个样本中，并将序列与公共序列数据库中的序列进行比较。对于所有三个基因座，尽管形态不同，但来自马里恩岛标本的序列几乎相同，系统发育分析将它们解析为油菜. 在系统发育树和物种特异性序列多态性的比较中，马里恩岛标本最接近一个进化枝，包括水生油菜L.,L. curdieanaF.穆尔。和L. 大调适用于 ITS 的 Diels 和最接近大号.澳大利亚对于质体基因座。细胞核不一致表明存在杂交或基因渗入的历史，这可能对形态变异和生态适应产生影响。