鳅超科鱼类体色体斑的演化及相关基因的进化分析

The remarkable diversity seen in the color pattern of many fishes is probably derived from their adaptation to environment or sexual selection or regulation by the related genes. The superfamily Cobitoidea is a group of small to medium-size benthonic fishes with beautiful and diverse color pattern which lead to the abundant biodiversity of the Cobitoidea..In this project, the pigment pattern evolution of the Cobitoidea will be investigated using Phylogenetic Comparative Methods (PCMs) with which the pigment pattern can be estimated the phylogenetically constrained extent and evolution rate. Many environmental factors will be measured, and the association between color pattern and environmental factors will be analyzed by Canonical Correspondence Analysis (CCA). Indoor sexual selection experiments of female preference for male color will be conducted to test the hypothesis that sexual selection drives the diversification of color pattern among closely relative species or conspecific individuals.To learn about the genetic base of pigment pattern evolution, the related genes including pigment genes and opsin genes will be cloned and sequenced. Based on the obtained phylogenetic relationships of the Cobitoidea, select pressure along each Cobitoidea lineage will be analyzed for these genes with analyzing their functions for the formation of pigment pattern, coevolution relationship between pigment and opsin genes, and estimating the divergence times among genes..Values of the present project lay in both basic theory and applications. For basic theory, this project will contribute to understand the general rule and mechanism of the color pattern formation in fishes, providing rich data resources for Evolutionary Biology. For applications, it can provide some references for selectively breeding excellent aquarium fishes.

许多鱼类具有鲜艳而多样的体色体斑，这可能与环境适应及性选择相关，也可能受相关基因的影响。鳅超科是一群美丽的中小型底栖鱼类，其体色体斑使该类群具有丰富的多样性。本项目拟采用系统发育比较方法，研究鳅超科鱼类体色体斑的演化过程，检测该特征在各类群中受系统发育限制的程度及演化速率等。测量各环境参数，采用典范对应分析探讨体色体斑与环境因子的关系。设计性选择实验，验证性选择促使近缘种或同种个体间体色体斑发生分化的假说。对体色体斑直接相关的基因和间接相关的视蛋白基因进行克隆测序，分析这些基因在鳅超科各类群中受到的选择压力及进化速率差异、在体色体斑形成中的作用、两类基因是否存在协同进化关系、基因间的分化时间等，从而研究体色体斑演化的分子基础。本项目的研究结果将有助于揭示鱼类体色体斑多样性形成的普遍规律及机制，丰富进化生物学的基础资料，也可以为观赏鱼优良品种的选育提供参考，具有重要的理论价值和实践意义。

研究生物的多样性及多样性起源是进化生物学的热点课题。体色斑纹是动物一个重要的多样化的特征，可能与其适应多样的环境有关，也可能受到内在遗传因素的影响。鳅超科鱼类具有丰富多样的体斑类型。本项目对赤水河流域干流及各支流鳅超科鱼类的分布及环境因子进行了全面的调查研究，结果表明，在调查的44个位点中，23个位点共有19种鳅超科鱼类分布；典范对应分析表明，在调查的9种理化因子中，水深、水流速度、水温、电导率是影响鳅超科鱼类分布（即体色体斑分布）的主要环境因子。对全国各大水系收集到的鳅超科鱼类，通过基因测序，构建可靠的系统发育树，采用系统发育比较方法研究了鳅超科鱼类体色斑纹的演化规律。结果表明，鳅超科体色斑纹的演化具有一定的规律，条鳅科和平鳍鳅科中的腹吸鳅亚科鱼类具有较为多样的体斑类型，这与其生活的水环境较为多样相关，但在一定程度上，也受到系统发育的限制；平鳍鳅类的体型存在趋同演化，且生活在江河中的类群，体型演化速率远高于生活在山溪中的类群。体色斑纹相关基因中，三个基因(MC1R, RH1和LWS1)一致显示，沙鳅科和花鳅科的进化速率都低于背景分支，暗示这两个科的这三个基因受到强烈的选择压力，从而导致其稳定的体色斑纹模式；而平鳍鳅科和条鳅科的都高于背景支，表明这些基因在这两个科中受到更松散的选择压力，具有更快的进化速率，从而使得这两个类群具有更为复杂多样的体斑模式。本项目的研究结果为生物多样性及其形成机制提供了部分数据支持，具有重要的科学意义。