ABSTRACT Ancient lakes are centres of biological diversification that hold many examples of adaptive radiation and species flocks. The recently discovered species flock of Cladophoraceae in Lake Baikal is a group of green algae that exhibit low genetic divergence in ribosomal markers (LSU, SSU, and ITS), but wide morphological differentiation. Microsatellite markers showed evidence of polyploidy in this group, requiring alternate data scoring methodologies. In this study, we use two clustering methods (STRUCTURE and Gaussian Clustering) to delineate species within 15 distinct morphotaxa of the cladophoralean Baikal clade. The two cluster analyses produced comparable results, although subtle differences in the assignment of individuals were observed. Our results indicate that many morphologically distinguishable species are discrete genetic clusters supporting reproductive isolation. This is the case for Chaetomorpha (= Ch.) baicalensis, the attached form of Ch. curta, Ch. moniliformis, Cladophora (= Cl.) compacta, and Cl. kursanovii. The unattached form of Ch. curta and a species of Rhizoclonium are recovered as growth forms of Ch. moniliformis and the attached form of Ch. curta, respectively. The remaining morphotaxa were not clearly delimited. While we have evidence for polyploidy within this species flock, it was not possible to determine the ploidy level of each individual with accuracy as no correlation in the number of alleles was observed between loci. A more detailed study including other sources of data, such as nuclear DNA content or chromosome counts, is required to demonstrate the ploidy changes and their role in speciation in these species.

中文翻译：

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遗传数据支持俄罗斯贝加尔湖地方性枝藻科（叶绿门）中的生殖隔离物种

摘要 古代湖泊是生物多样化的中心，拥有许多适应性辐射和物种群落的例子。最近在贝加尔湖发现的枝藻科物种群是一群绿藻，它们在核糖体标记（LSU、SSU 和 ITS）上表现出低遗传差异，但形态差异很大。微卫星标记显示该组中存在多倍体的证据，需要替代数据评分方法。在这项研究中，我们使用两种聚类方法（结构和高斯聚类）来描绘枝状贝加尔湖进化枝的 15 个不同形态分类群内的物种。尽管观察到个体分配的细微差异，但两种聚类分析产生了可比较的结果。我们的结果表明，许多形态上可区分的物种是支持生殖隔离的离散遗传簇。Chaetomorpha (= Ch.) baicalensis 就是这种情况，Ch 的附加形式。Curta, Ch. 念珠菌属、枝状菌属（= Cl.）致密类和 Cl。库萨诺维 Ch的独立形式。curta 和一种根瘤菌作为 Ch 的生长形式被回收。念珠菌和Ch的附着形式。库塔，分别。其余的形态分类群没有明确界定。虽然我们有该物种群内多倍性的证据，但由于在位点之间未观察到等位基因数量的相关性，因此无法准确确定每个个体的倍性水平。更详细的研究，包括其他数据来源，例如核 DNA 含量或染色体计数，