The molecular basis of phenotypic plasticity and genetic assimilation in rapidly evolving lineages of East African cichlid fishes

东非慈鲷快速进化谱系的表型可塑性和遗传同化的分子基础

• 批准号: 274606803
• 负责人: Professor Dr. Axel Meyer
• 金额: --
• 依托单位: Institut für Genetik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/274606803?language=en
• 关键词: molecular; basis; phenotypic; plasticity; genetic

An organisms ability to adjust its phenotype in response to environmental stimuli is termed phenotypic plasticity. Traditionally it is often seen to hamper and constrain evolution. However, this view is debated and alternatively the flexible-stem hypothesis of West-Eberhard suggest the opposite, that exactly phenotypic plasticity (and what she calls developmental recombination) facilitates in stem lineages of adaptive radiations their rapid evolution and speciation into many specialized and less plastic species that then make up adaptive radiations. Based on this hypothesis developmental plasticity is seen to lead evolutionary change that later, even in lack of the initial environmental stimulus, is phenotypically expressed in alternative phenotypes through genetic assimilation. Here, we set out test the predictions of the flexible-stem hypothesis (FSH) in a set of four carefully chosen representative cichlid fish species from the adaptive radiations of Lake Victoria and Lake Malawi and two riverine basal lineages. Cichlid fishes have undergone explosive adaptive radiations in several East African lakes, filling a vast array of ecological niches, and thus represent an ideal model in which to test this hypothesis. In previous work and in preliminary experiments we could induce in split-broods different types of teeth and pharyngeal jaw morphologies based on the hardness of the diets that was fed to the fish (hard snails vs. crushed snails). It was possible to produce drastically different feeding morphologies in one of the non-endemic riverine cichlids. In accordance with the FSH we expect that the reaction norms will be much smaller in both of the two pairs of specialized and derived species from the adaptive radiations of Lakes Victoria and Malawi. In previous RNA-seq experiments and later work we identified several sets of co-expressed genes that were active during different phases of the jaw transformation towards a durophagous (snail-crushing) jaw. We plan to do conduct feeding-experiments with all six species as well as RNA-seq analyses that will be analyzed and interpreted within a known phylogenetic framework. We anticipate that both the variation in morphology as well as in transcriptional will be smaller in the four derived and specialized endemic members of the adaptive radiations (that are of different ages) than in the two basal species as would be predicted by the FSH. Further bioinformatics analyses will investigate variation and changes in promoters of genes involved in the adaptive phenotypic response and compared with other sets of neutral genes.

一个有机体能够调整其表型以响应环境刺激的能力被称为表型可塑性。传统上，它经常被视为阻碍和限制进化。然而，这种观点是有争议的，或者韦斯特-埃伯哈德的柔性茎假说提出了相反的观点，即表型可塑性（以及她所谓的发育重组）促进了适应性辐射的茎谱系的快速进化和物种形成，成为许多专门化的和可塑性较小的物种，然后构成适应性辐射。基于这一假设，发育可塑性被认为是导致进化的变化，后来，即使在缺乏最初的环境刺激，是通过遗传同化的替代表型表型表达。在这里，我们列出了测试的灵活的干假说（FSH）的预测，在一组精心挑选的四个代表慈鲷鱼种的适应辐射的维多利亚湖和马拉维湖和两个河流的基底谱系。慈鲷鱼经历了爆炸性的适应性辐射在几个东非湖泊，填补了大量的生态位，从而代表了一个理想的模型，以测试这一假设。在以前的工作和初步实验中，我们可以根据喂给鱼的饮食的硬度（硬蜗牛与压碎的蜗牛）在分裂育雏中诱导不同类型的牙齿和咽颚形态。这是可能产生显着不同的喂养形态在一个非特有的河流慈鲷。根据FSH，我们预计，反应规范将小得多，在两对专门的和派生的物种从适应辐射的湖泊维多利亚和马拉维。在以前的RNA-seq实验和后来的工作中，我们确定了几组共表达基因，这些基因在颌骨向硬食（蜗牛粉碎）颌骨转化的不同阶段都有活性。我们计划对所有六个物种进行喂食实验，并进行RNA-seq分析，这些分析将在已知的系统发育框架内进行分析和解释。我们预计，无论是在形态上的变化，以及在转录将是较小的四个衍生的和专门的地方性成员的适应性辐射（是不同的年龄）比在两个基础的物种，将由FSH预测。进一步的生物信息学分析将研究参与适应性表型反应的基因启动子的变异和变化，并与其他中性基因组进行比较。