传统稻-鱼系统中“田鱼”的遗传多样性及其生态效应

Genetic diversity in agricultural system has helped to increase crop yield and to maintain the stability of agricultural productions. Genetic diversity, however, has been eroded in the industrialization of agriculture in the last decades. Thus, how to maintain and utilize genetic diversity in agricultural system have been concerned recently. The overall goals of this grant project is to investigate the genetic diversity of an indigenous common carp in traditional rice-fish system, which was listed as one of the Globally Important Agriculture Heritage System (GIAHS) in 2005 by Food and Agriculture Organization (FAO) of the Unit Nations, and to examine ecological consequence of this carp genetic diversity. The central hypotheses are: (1) genetic diversity and ecologucal differenciation of this indigiouns carp in traditional rice-fish system may be generated due to the selections from both nature and human; (2) the genetic diversity and ecologucal differenciation may help to increase the fitness and resource utilization of this carp population in rice field. Specific objectives of this project are: (1) to characterize genetic diversity of the indigenous common carp in traditional rice-fish system by sampling from different geographical locations and using molecular methods; (2) to test the ecological differentiation (e.g. growth rate, behavior, and feeding) of this common carp through common garden experiment and using the techniques of stable isotope and camera trap; (3) to examine how a genetic diversified carp population can result in higher survival and growth rate and higher efficiency of resource use in rice field. The significance of this project is that it demonstrates the roles of traditional agriculture system in preserving genetic diversity, and the contribution of small farmer household. It is also important to understand how higher genetic diversity results in the increase of population fitness and ecosystem functioning.

农业现代化过程导致遗传多样性大量流失，如何保持农业系统遗传多样性并发挥其生态效应倍受关注。本项目以全球重要农业文化遗产系统-“稻鱼共生系统”为范例，通过大范围的多点取样和采用分子生物学的方法，研究分布于我国传统稻鱼共生系统中的土著“田鱼”的遗传多样性及其所受地理隔离的影响；研究不同地理小种群的遗传结构和亲缘关系；并采用同质园实验方法以及稳定性同位素技术和摄像记录观察技术，研究“田鱼”种群的生态分化（行为、取食、生长等差异）；并研究“田鱼”种群的生态分化是否利于个体间的合作（如互补利用食物资源等）从而达到充分利用资源、提高种群适合度（存活率和整体生物量）的目的。研究结果将阐明农业系统保育遗传多样性的可能途径；并揭示遗传多样性的生态学效应。研究将充实遗传多样性的生态系统功能这一领域的研究，具有较大科学价值；也可为农业系统保持和利用遗传多样提供参考。

农业现代化过程导致遗传多样性大量流失，如何保持农业系统遗传多样性并发挥其生态效应倍受关注。本项目以全球重要农业文化遗产系统-“稻鱼共生系统”为范例，通过大范围的多点取样和采用分子生物学的方法，研究分布于我国传统稻鱼共生系统中的土著“田鱼”的遗传多样性及地理隔离的影响；研究不同地理的小种群的遗传结构和亲缘关系；并采用同质园实验方法以及稳定性同位素技术和摄像技术，研究“田鱼”种群的生态分化（行为、取食、生长等差异）；并研究“田鱼”种群的生态分化是否利于个体间的合作（如互补利用食物资源等）从而达到充分利用资源、提高种群适合度（存活率和整体生物量）的目的。经3年研究，完成了项目计划的研究内容和目标, 重要研究进展如下：（1）通过线粒体D-loop基因设计引物进行的遗传分析发现，分布于传统稻鱼系统的“田鲤鱼”为独特的普通鲤鱼地方种群；形态分析也表明长期在稻田演化的田鲤鱼在形态上也产生分化。（2）微卫星分析表明传统稻鱼系统的“田鲤鱼”维持有高的遗传多样性；景观遗传学方法进一步揭示农户连接（farmer connectivity）对田鱼基因流的影响是多样性维持的机制。（3）摄像技术、稳定性同位素技术和形态分析技术相结合的研究发现，3个遗传类群的田鱼在形态（体型和体色）、行为、觅食和生长上的存在差异，这种差异使得3个遗传类群的田鱼共存时对资源的利用更加充分，种群的适合度提高。研究结果阐明了传统农业系统保育遗传多样性的可能途径；并揭示遗传多样性的生态学效应。研究将充实遗传多样性的生态系统功能这一领域的研究，具有较大科学价值；也可为农业系统如何保持和利用遗传多样提供参考。