团头鲂3个选育群体的选择压力分析

Selective Pressure on Three Selective Breeding Populations of Blunt Snout Bream Megalobrama amblycephala

团头鲂选育群体基因组选择信号的检测有助于研究人工选育条件下基因组的进化机制,为团头鲂的进一步遗传改良提供依据。以团头鲂"浦江1号"选育奠基群体(F0)为对照组,以3个团头鲂选育群体为试验组,采用经典的Ewens-Watterson中性检验和基于3种算法(岛屿模型、分级岛屿模型、贝叶斯似然法)的FST-离群值点检验,在14个转录组微卫星位点上进行选择信号检测。结果显示,F0群体中所有位点均为中性位点,选育群体A在Mac927位点和Mac158位点受到了正向选择压力,选育群体B在Mac158位点受到了正向选择压力,选育群体C在Mac927位点和Mac158位点受到了正向选择压力。由此可见,自1985年起的连续世代人工选育已在团头鲂基因组中留下了可检测到的选择信号。3个选育群体均在Mac158位点检测到选择信号,表明3个选育群体受到的人工选择方向比较接近。

Identification of selection signatures in genomic regions of selective breeding populations of blunt snout bream （Megalobrama amblycephala） leads to contribute not only to the study of evolution mecha- nisms of genome under artificial selection, but also to provide the basis for further genetic improvement. A population genetic approach, using a classical Ewens-Watterson neutrality test and three algorithms （Is- land model, Hierarchical island model, and Bayesian likelihood method） of Fs^-outlier detection methods, was employed to evaluate polymorphism in fourteen transcriptomic microsatellite loci in order to identify loci that may be candidates for selection amongst four populations （three selective breeding populations and one foundation population of ＂Pujiang 1＂ selected strain） of blunt snout bream. The results showed that no selection signature was detected in foundation population （F0）. Two loci （Mac927 and Mac158） showed significant evidence of positive artificial selection in both selective breeding population A and population C. Only one loci （Mac158） experienced positive artificial selection in selective breeding population B. The findings indicated that detectable selection signatures were found in the genome of blunt snout bream by successive generations of artificial selection since 1985. The selection signature of Mac158 was detected in each selective breeding population, indicating that there was similar direction of artificial selection in the three selective breeding populations.