近交对凡纳滨对虾(Litopenaeus vannamei)生长、存活及抗逆性的影响

EFFECTS OF INBREEDING ON GROWTH,SURVIVAL AND STRESS RESISTANCE IN LITOPENAEUS VANNAMEI

通过设计交配组合,建立中度近交组GM(近交系数大于0.25,家系G1,G2,G3,G4)、轻度近交组GL(近交系数0.0625—0.25,家系Z1,Z2,Z3,Z4),非近交组GN(近交系数为0,家系F1,F2,F3,F4),比较共同环境养殖90d不同近交程度凡纳滨对虾(Litopenaeus vannamei)家系体质量(BW)、存活率(SR)、高氨氮耐受存活率(SRA)及低溶氧耐受存活率间(SRH)的差异性,计算近交家系相关性状的近交衰退系数,评价近交对凡纳滨对虾生长、存活和抗逆性的影响。结果显示:GN组BW为7.66±2.86g,显著高于GM组BW(P<0.05);GL组SR、SRA、SRH间差异近交衰退系数为–6.41%、–13.63%、–11.84%;GM组的SR、SRA、SRH的近交衰退系数为5.30%、–4.73%、–4.77%;Z2的BW最大为8.59±3.85g,G3的BW高于GN组均值;G2家系SR为84.81%±10.37%,显著高于其它家系(P<0.05);75%的近交家系表现出SR近交衰退,62.5%的近交家系表现出SRH近交衰退。结果表明:近交导致凡纳滨对虾生长、高氨氮耐受性及低溶氧耐受性的衰退普遍存在,应避免高度近交个体的产生,近交系数应控制在0.25以下;少数近交家系的生长、存活、高氨氮耐受性或低溶氧耐受性优于非近交家系,推测选择合理亲缘选配方案可加快凡纳滨对虾遗传改良进程。

We conducted a comparative study on body weight （BW）, survival rates in 96 h under high-concentration ammonia （SRA） or hypoxia （SRH） for Litopenaeus vannamei families of different inbreeding degrees. The study was performed in a normal environment for 90 d. Three groups each having four families were set up in terms of inbreeding degree, i.e., the group of moderate inbreeding degree （GM） whose inbreeding coefficients （IC） were 〉0.25, that of light degree （GL） （IC between 0.0625 and 0.250）, and that of zero degree （GN） （an outbred group, IC at 0）. In addition, the inbreeding depression coefficient was calculated. The results show that the BW of GN was 7.66±2.86g, which was significantly higher than that of GM. The difference between SR, SRA and SRH of GL and GN were not significant. The inbreeding depression coefficient of SR, SRA, and SRH of GL were -2.05%, -1.35% and -1.07%, while those of GM were 0.93%, -0.89% and -0.76%, respectively. The maximum BW occurred in GL for 8.59~3.85g. The maximum SR was in GM for 84.81%＋10.37%, which is well above the others＇. Of all the inbred families, 75% presented inbreeding depression in SRA, and 62.5% in SRH. In other words, inbreeding depression was a common consequence for L. vannamei in growth performance and tolerance to high-concentration ammonia or hypoxia. Therefore, highly-inbred individuals should be avoid and the IC should be selected below 0.25. However, few inbred individuals showed better performance in growth and tolerance against high-concentration ammonia or hypoxia. Above all, by selecting an appropriate mating strategy, the shrimp breeding could be improved and benefited.