Embracing discordance: phylogenomic analyses provide evidence for allopolyploidy leading to cryptic diversity in a Mediterranean Campanula (Campanulaceae) clade

The Mediterranean Basin harbors a remarkable amount of biodiversity, a high proportion of which is endemic to this region. Here, we present an in-depth study of an angiosperm species complex, in which cryptic taxonomic diversity has been hypothesized. Specifically, we focus on four currently recognized species in the Roucela complex, a well-supported clade in the Campanulaceae/Campanuloideae: Campanula creutzburgii, C. drabifolia, C. erinus, and C. simulans. This study takes a phylogenomic approach, utilizing near-complete plastomes and 130 nuclear loci, to uncover cryptic diversity and test hypotheses regarding hybridization and polyploidy within this clade. Genome size estimates recovered tetraploid and octoploid lineages within the currently recognized, widespread species C. erinus, showing an east-west geographic pattern. Though genomic data clearly differentiate these two cytotypes, we failed to discern morphological differences. The formation of a cryptic octoploid lineage, distri...地中海盆地（Mediterranean Basin）孕育了极为丰富的生物多样性，其中极高比例的类群为该区域特有。本研究针对一个被推测存在隐蔽分类多样性的被子植物物种复合体（angiosperm species complex）展开深入分析。鲁塞拉复合体（Roucela complex）是桔梗科（Campanulaceae）桔梗亚科（Campanuloideae）中一个得到充分支持的演化支，我们聚焦于该复合体内目前被认可的4个物种：Campanula creutzburgii、C. drabifolia、C. erinus及C. simulans。本研究采用系统发育基因组学方法，借助近乎完整的质体基因组（plastomes）与130个核基因座（nuclear loci），以揭示该演化支内的隐蔽分类多样性，并检验关于杂交与多倍体化（polyploidy）的相关假说。基因组大小估算结果显示，在当前被广泛认可的广布物种C. erinus中存在四倍体（tetraploid）与八倍体（octoploid）演化支，其分布呈现东西向地理格局。尽管基因组数据可明确区分这两种细胞型（cytotypes），但我们未观测到二者存在形态学差异。一个隐蔽八倍体演化支的形成，分布……