The western Balkans represents an area of significant topographic and environmental heterogeneity, harbouring high species and intraspecific diversity. Similar genetic and distributional splits observed in unrelated species have suggested some common features in their glacial response and biogeographic history. Here, we studied the western Balkan endemic Alyssum austrodalmaticum with the aim to explore and understand its intraspecific structure and processes that shaped the present patterns. We employed data from AFLPs, two low-copy nuclear genes, genome size, morphometrics and species distribution modelling. Four genetic lineages were identified within the species, which were geographically structured and showed cytotype-specific patterns. The observed phylogeographic structure is congruent with the predicted species distribution during the Last Glacial Maximum. Two allopatric diploid lineages (referred to as N2x and S2x) reflect glacial range disruption and survival in distinct refugia inferred in north-western (Istria, Kvarner) and south-eastern Adriatic areas (northern Adriatic palaeo-coastline and southern Dinarides). AFLP analyses with in silico-generated polyploid genotypes and nuclear genes proved that the two tetraploid lineages (C4x, S4x) were genetic allopolyploids and arose independently. The central tetraploids (C4x) originated through secondary contacts of the two diploid lineages. The origin of the southern tetraploids (S4x) is somewhat ambiguous. Apart from the southern diploids (S2x), the involvement, either direct or through later introgression, of the central tetraploids (C4x) or even other Balkan relatives is possible. Our study highlights the role of glacial range dynamics and secondary contacts, triggering introgression and polyploid evolution, in the formation of genetic diversity and intraspecific patterns in the western Balkans.

中文翻译：

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更新世范围破坏和冰后扩张与二次接触解释了巴尔干西部特有的 Alyssum austrodalmaticum（十字花科）的遗传和细胞型结构

巴尔干西部地区具有显着的地形和环境异质性，拥有丰富的物种和种内多样性。在无关物种中观察到的类似遗传和分布分裂表明它们的冰川反应和生物地理历史具有一些共同特征。在这里，我们研究了巴尔干西部特有的 Alyssum austrodalmaticum，目的是探索和了解其种内结构和形成当前模式的过程。我们采用了来自 AFLP、两个低拷贝核基因、基因组大小、形态计量学和物种分布建模的数据。在该物种内确定了四个遗传谱系，它们具有地理结构并显示出特定于细胞类型的模式。观察到的系统地理学结构与末次盛冰期的预测物种分布一致。两个异域二倍体谱系（称为 N2x 和 S2x）反映了在亚得里亚海西北部（伊斯特拉、克瓦内尔）和亚得里亚海东南部（亚得里亚海北部古海岸线和迪那里德南部）推断出的不同避难所中冰川范围的破坏和生存。使用计算机生成的多倍体基因型和核基因进行的 AFLP 分析证明，两个四倍体谱系（C4x、S4x）是遗传异源多倍体并独立出现。中心四倍体 (C4x) 起源于两个二倍体谱系的二次接触。南方四倍体 (S4x) 的起源有些模糊。除了南方二倍体 (S2x) 之外，直接或通过后来的基因渗入参与，中央四倍体 (C4x) 甚至其他巴尔干亲属是可能的。我们的研究强调了冰川范围动态和次生接触的作用，触发基因渗入和多倍体进化，在巴尔干西部遗传多样性和种内模式的形成中。