日本蟳南北地理群体对温度选择的适应性演化机制研究

在群体水平认识海洋生物响应温度变化的分子适应演化机制，是理解海洋生物如何应对全球气候变暖遗传响应过程的基础。目前有关海洋生物群体温度适应进化研究一般未区选择压力来自高温影响还是低温影响，并且忽视年温差变化带来环境选择压力。我们以中国近海南北分布的蟹类日本蟳（Charybdis japonica）为研究对象，首次从温度高低和温差两个维度开展群体温度适应进化研究，采用全基因组重测序结合不同群体受选择基因表达量分析，在全基因组水平阐明其精确的遗传结构，识别基因组受选择区域和受选择基因；结合温度胁迫实验，解析受选择基因在不同温度胁迫实验条件下表达调控网络，挖掘出群体冷适应、热适应和温差适应关键基因。评估高温、低温和年温差等3种温度选择压力，在温度和温差两个维度上对于各群体适应进化的影响，解析不同群体温度适应进化方向。本项目研究结果将在基因组层面和基因表达层面阐释南北群体对温度选择作用适应演化机制。

Understanding the molecular adaptation mechanisms of marine organisms in response to temperature changes at the population level is the basis for understanding how marine organisms respond to the global climate warming genetic process. Previous studies on temperature adaptation evolution of marine organisms generally study population adaptation evolution under temperature gradient changes on a one-dimensional scale. It does not distinguish whether the selection pressure of adaptive evolution signals comes from the influence of high temperature or low temperature. It ignores the environmental selection pressure caused by the annual range of temperature. Coastal water of China is a high-risk area for global climate change. The difference in the temperature environment between the northern and southern sea areas provides a temperature environment setting for high-temperature pressure, low-temperature pressure and annual temperature variation, which are ideal natural experimental conditions for research on the genetic variation of populations due to climate change. We select widely distributed crab species Charybdis japonica as a model species. For the first time, the thermal adaptation evolution study for populations is carried out from the two dimensions of temperature value and temperature range. We will use whole genome resequencing combination with analysis of the expression of selection genes in temperature tolerance experiments. The fine genetic structure will be clarified at the genome-wide level. We will compare the genomic regions between north and south populations under temperature selection, the geographical differences and the localized chromosomal differences of the selection genes. Based on the temperature stress experiments, we analyzed the expression regulatory network of selected genes under different temperature stress experimental conditions and mine the key genes involved in cold adaptation, heat adaptation, and temperature difference adaptation. The present study will assess the contribution of the three temperature selection drivers, namely, high temperature, low temperature and annual temperature change, on the adaptation evolution of C. japonica population, identify the main sources of temperature selection pressure in different populations, and identify the thermal adaptation evolutionary direction for different populations. The thermal adaptive evolutionary mechanisms for north and south populations will be revealed at the genome and gene expression levels. The results of this project will show the evolutionary direction of thermal adaptation since the formation of the populations and uncover the mechanisms of response strategies of the different geographic population of crabs under temperature selection.