Semi-permeable species boundaries in Iberian barbels (Barbus and Luciobarbus, Cyprinidae)

Background: The evolution of species boundaries and the relative impact of selection and gene flow on genomic divergence are best studied in populations and species pairs exhibiting various levels of divergence along the speciation continuum. We studied species boundaries in Iberian barbels, Barbus and Luciobarbus, a system of populations and species spanning a wide degree of genetic relatedness, as well as geographic distribution and range overlap. We jointly analyze multiple types of molecular markers and morphological traits to gain a comprehensive perspective on the nature of species boundaries in these cyprinid fishes. Results: Intraspecific molecular and morphological differentiation is visible among many populations. Genomes of all sympatric species studied are porous to gene flow, even if they are not sister species. Compared to their allopatric counterparts, sympatric representatives of different species share alleles and show an increase in all measures of nucleotide polymorp...研究背景：物种边界的演化，以及选择与基因流（gene flow）对基因组分化（genomic divergence）的相对影响，最佳研究对象为沿物种形成连续体（speciation continuum）呈现不同分化程度的种群与物种类群对。本研究聚焦伊比利亚须鲃（Iberian barbels）类群，涵盖鲃属（Barbus）与Luciobarbus属的类群，该系统包含遗传亲缘度跨度广泛、地理分布与分布重叠情况各异的种群与物种类群。我们联合分析多种分子标记（molecular markers）与形态性状（morphological traits），以期全面解析这类鲤科鱼类（cyprinid fishes）的物种边界本质。 结果：多个种群间均可见种内分子与形态分化。本次研究涉及的所有同域分布（sympatric）物种，即便并非姊妹物种（sister species），其基因组均存在基因流渗透现象。与异域分布（allopatric）的同类群相比，不同物种的同域代表类群共享等位基因，且在各项核苷酸多态性（nucleotide polymorphism）指标上均表现出升高趋势……