Study on simulation of minimal kinship selective breeding for conservation of genetic diversity in successive artificial bred lines in fish

在鱼类制种工业中，由于种子是用较小的育苗有效规模繁殖的，因此通常产生具有高近交系数值的种子群体。在这种近交群体中发生的随机遗传漂变、近交抑制、无意识选择等导致的遗传变化可能对野生群体产生不可恢复的影响。在这个项目中，本文通过对具有重要经济价值的鱼类人工繁殖种子种群的遗传变化进行评价，为保护野生种群的遗传管理提供依据：1)开发有效的遗传标记，如DNA多态性；2)积累野生种群和人工繁殖种群结构和多样性的遗传数据；3)开发模拟系统，生成基因型利用亲缘关系最小选择育种保护亲缘关系种群和野生种群的遗传多样性；为保护亲缘关系种群和野生种群的遗传多样性制定制种指南；采用水产养殖种、种群强化种和濒危种的代表性鱼种；如巴芬比目鱼；湄公河巨型鲶鱼Pangasianodon gigas和sakuramasu Oncorhynchus masou。我们收集了这些鱼类的DNA标记基因型数据，进行了种群遗传分析和模拟研究。利用本项目开发的最小亲缘选择育种软件，通过30代重复虚拟繁殖试验，考察了最佳选择条件。结果表明，等位基因平均数量相等是保存遗传变异的最佳条件，野生群体中存在杂合现象。该方法可在有效种群数量小于最小生存种群数量（Ne=50）的情况下，保持各种群种群间足够的遗传分化水平。少

In the fish seed production industry, seed populations with high value of inbreeding coefficient are usually produced because the seeds are reproduced using smaller effective size of brood stock. The genetic changes caused by random genetic drift, inbreeding depression, unconscious selection happened in such inbreeding population may give un-restorable effects on wild population.In this project, we tried to evaluate genetic changes happened in the artificially reproduced seed population for stock enhancement programs of economically important fish species to find up way for genetic management to conserve wild populations based on following actions :1) to develop efficient genetic markers such as DNA polymorphism2) to accumulate the genetic data of population structure and diversity of both the wild and artificially propagated populations3) to develop a simulator to generate genotypes of offspring using genetic data of brood stock in artificial seed production4) to develop a simulator t … More o perform minimal kinship selective breeding for conservation of genetic diversity in the brood stock and wild population5) to make guideline for seed production to preserve genetic diversity in the brood stock and wild populationThe fish species used were representative species from aquacultured species, stock enhanced species and endangered species, such as barfin flounder Verasper moserz; Mekong gigantic catfish Pangasianodon gigas, and sakuramasu Oncorhynchus masou. We collected genotype data of DNA markers for the population genetic analysis and simulation studies for these fishes.Using the soft wares developed in this project for minimal kinship selective breeding, the optimum conditions for selection were examined by repetitive virtual reproduction trials for 30 generations. We found the best condition to conserve the genetic variation being equivalent level of the average number of alleles, and heterozygosity observe in the wild population. This method were useful to conserve the enough level of genetic divergence of brood stock in each species, even if the effective size of brood stock are not enough being less than minimum viable size of population (Ne=50). Less