The Genomic Basis of Electric Signal Diversity

通讯信号在新物种的进化中很重要，许多物种的歌声、颜色图案和信息素都有精心设计的变化，这就是明证。在许多这样的系统中，产生这种变异的机制知之甚少，限制了理解选择如何作用于通讯信号以促进物种形成过程的能力。电鱼，如来自非洲的海鱼，会产生微弱的电场，以便在其环境中进行通信和导航。电鱼有200多种；大多数种类都有特定的放电，其产生的机制已经被很好地理解了。在这个项目中，研究人员试图通过利用最近发现的具有不同电信号的桑迪电鱼种群之间的“杂交区”来识别导致电信号差异的基因，从而确定电信号多样性的遗传基础。该项目将利用下一代基因组测序技术，以及开发新的电鱼转基因技术。这项研究很重要，因为电场在物种识别中至关重要，而识别导致物种行为差异的基因最终将有助于生物学家理解行为的变化如何促进或可能导致一个物种成为多个物种。与这项工作相关的是，该项目将在密歇根州奥利维市的中学生中建立一个新的教育推广计划，重点是“能量的形式”。200多个标称物种的Mormyrids产生容易测量和量化的放电信号(EOD)，这些信号具有离散的解剖学和生理学基础。EOD信号通常是物种特有的，已被证明是求偶行为的一个必要组成部分，特别是对于Parormyrops属快速进化的Mormyrids“物种群”。最近的工作重点是将这些电信号多样性的宏观进化模式与种群水平的过程联系起来。最近的研究发现，王氏副魔头鱼的EOD信号在种群水平上存在多态，这反映了金丝鱼和其他Mormyrids的EOD多样性的宏观进化模式。本项目的目的是确定王氏松毛虫分化信号的遗传基础。研究人员将通过完成三个具体目标来实现这一目标。第一个目标是通过组装参考金丝鱼基因组来确定共面、多态的电鱼物种之间的差异基因组区域，然后比对具有不同EOD类型的个体的低覆盖率全基因组重测序数据。假设是这些种群间的基因组区域的差异导致了EOD复杂性的差异。第二个目的是确定与EOD复杂性相关的基因在近缘副魔芋物种中的表达模式。假设EOD复杂性的差异将与与电细胞形状和结构相关的基因表达的变化有关。第三个目的是测试通过干扰体内基因功能而确定的候选基因组区域和/或基因表达变化的推定效果。通过实现这三个目标，该项目将首次展示脊椎动物交流行为的遗传基础。尽管这两种信号类型在共处的、完全杂交的种群中保持着，但金斯利氏沼虾仍保持着EOD的多样性。这些差异代表了与物种和属之间的生殖隔离进化密切相关的相同的排泄物特征。该项目的成果将广泛地有助于理解进化新颖性如何在自然种群中产生，自然种群是物种形成的底物。该项目将通过在http://efishgenomics.zoology.msu.edu.网站上建立基于网络的工具来交换电鱼的表型和基因组数据，从而加强研究的基础设施这项研究的国际部分得到了美国国家科学基金会国际科学与工程办公室的部分支持。

Communication signals are important in the evolution of new species, as evidenced by many groups of species with elaborate variation in songs, color patterns, and pheromones. In many of these systems, the mechanisms that produce this variation are poorly understood, limiting the ability to understand how selection acts on communication signals to facilitate the speciation process. Electric fish, such as mormyrid fishes from Africa, produce weak electric fields for the purposes of communication and navigation through their environments. There are more than 200 species of mormyrid electric fish; most species have a specific electric discharge, and the mechanisms underlying the production are well understood. In this project, the researchers seek to identify the genetic basis of electric signal diversity by leveraging the recent discovery of a "hybrid zone" between populations of mormyrid electric fish with distinct electric signals to identify genes responsible for differences in electric signals. The project will draw on next-generation genomic sequencing technologies, as well the development of new transgenic techniques in electric fish. This research is important because electric discharges are critical in species recognition, and identifying genes responsible for behavioral differences within species will ultimately help biologists understand how changes in behavior can facilitate, or perhaps cause, one species to become multiple species. In connection with this work, this project will establish a new educational outreach program, focusing on "forms of energy," to middle school students in Olivet, MI.The more than 200 nominal species of mormyrids produce easily measured and quantified electric discharge signals (EODs), which have a discrete anatomical and physiological basis. EOD signals are typically species-specific and have been demonstrated to be a necessary component of courtship behavior, particularly for a rapidly evolved "species flock" of mormyrids in the genus Paramormyrops. Recent work has focused on linking these macroevolutionary patterns of electric signal diversity to population-level processes. Recent discoveries have identified a population level polymorphism in EOD signals within the species Paramormyrops kingsleyae that reflects macroevolutionary patterns of EOD diversity in Paramormyrops and other mormyrids. The objective of this project is to determine the genetic basis of divergent signals in P. kingsleyae. The researchers will achieve this objective by completing three specific aims. The first aim is to determine the divergent genomic regions between sympatric, polymorphic species of electric fish by assembling a reference P. kingsleyae genome, and then align low-coverage whole genome resequencing data from individuals with divergent EOD types. The hypothesis is that these divergent genomic regions between populations are responsible for differences in EOD complexity. The second aim is to identify patterns of gene expression correlated with EOD complexity among closely related Paramormyrops species. The hypothesis is that differences in EOD complexity will be associated with changes in expression of genes relating to electrocyte cell shape and structure. The third aim is to test the putative effects of candidate genomic regions and/or changes in gene expression identified by interfering with gene function in vivo. By achieving these three aims, this project will provide the first demonstration of the genetic basis of a vertebrate communication behavior. EOD diversity is maintained by P. kingsleyae despite the fact that both signal types are maintained in sympatric, fully interbreeding populations. These differences represent the same EOD characteristics that have been strongly implicated in the evolution of reproductive isolation between species and genera. The outcomes of this project will contribute broadly to understanding how evolutionary novelty arises in natural populations, a substrate for speciation. This project will enhance infrastructure for research by constructing web-based tools for exchanging phenotypic and genomic data in electric fish on the website http://efishgenomics.zoology.msu.edu. The international component of this research is supported in part by the National Science Foundation's Office of International Science and Engineering.