Pattern and processes of cichlid speciation along a geographical gradient in the Lower Congo River: Are species complex genomic networks?

种间和种内的基因流动越来越被认为是形成物种多样化和形成的重要因素。本文研究了刚果河下游急流特有的5种小型慈鲷（Teleostei: Cichlidae，每种3-10种）的系统发育、系统地理和种群基因组学。在刚果河下游连续的单向地形中，脂肪类、纳米色类、单色类、telegramma和Lamprologus属的五种形态和/或生态分化谱系的平行进化，允许在准同源和部分同域的地理环境下，用基因流和杂交物种形成假设来测试物种形成。在之前系统地理学和形态计量学研究结果的基础上，我们将利用下一代测序、稳定同位素分析和几何形态计量学来评估刚果河下游因加急流处约16公里长的每条鱼群的基因组-表型-环境关联。这种方法将使我们有机会(1)识别和比较在相同条件下跨物种的适应性和非适应性异居群差异的基因组特征。它将进一步允许(2)识别和分析基因组结构在二次渗入之后的变化，在至少一个案例中，在同倍体杂交物种形成之后，这很可能发生在以前的异域谱系的二次接触之后。该研究将有助于人们对遗传渗入和杂交在新物种起源中的作用有一个普遍的认识。

Inter- and intraspecific gene flow is increasingly recognized as an important factor shaping diversification and speciation. We study the phylogeny, phylogeography and population genomics of five small cichlid species assemblages (Teleostei: Cichlidae; 3-10 species each) endemic to the rapids of the Lower Congo River. The parallel evolution of five morphological and/or ecological divergent lineages of the genera Steatocranus, Nanochromis, Haplochromis, Teleogramma and Lamprologus within the contiguous unidirectional topography of the Lower Congo River allows testing of speciation with gene flow and hybrid speciation hypotheses under parapatric and partially sympatric geographical settings. Building on own previous phylogeographic and morphometric results, we will take advantage of Next Generation Sequencing, stable isotope analysis and geometrical morphometrics to assess genome-phenotype-environment associations for each cichlid assemblage along an approximately 16 km long stretch of the Lower Congo River at the rapids of Inga. This approach will give us the opportunity (1) to identify and compare genomic signatures of adaptive vs. non-adaptive parapatric population divergence across species under identical conditions. It will further allow to (2) identify and analyze changes of genomic architecture after secondary introgression and, in at least one case, after homoploid hybrid speciation, which most likely took place after secondary contact of previously allopatric lineages. The study will contribute to the general understanding of the role of introgression and hybridization for the origin of new species.