黑颈乌龟两个养殖种群的遗传多样性分析

Genetic Diversity Analysis of Two Cultured Populations of Mauremys nigricans

开展濒危物种养殖群体的遗传多样性研究,对种质资源的保护与利用具有重要意义。选择线粒体COI基因作为本次研究的分子标记,分别从序列组成、单倍型及遗传距离、种群历史动态等方面对黑颈乌龟(Mauremys nigricans)两个养殖种群进行比较分析。结果显示:两个种群的COI序列全长572 bp,A+T含量为55.4%,G+C含量为44.6%。广东种群的遗传多样性指标均高于广西种群。其次,两个种群共享15个单倍型,广东种群内部的遗传距离(0.002~0.024)高于广西种群内部(0.002~0.011),可见广东种群具有更加丰富的遗传变异。中性检验结果显示种群间的遗传分化达到较高水平(Fst=0.20593),AMOVA分析结果证明种群内部变异在两个种群的遗传分化中占据主要作用(79.41%)。最后,核苷酸错配分布曲线和中性检验结果揭示广西种群经历了种群扩张,然而在扩张过程中并未有效积累核苷酸变异,建议避免杂交,加强同一物种不同群体间的基因交流,并优先保护群体中个体占有率低的单倍型。本研究为黑颈乌龟的遗传多样性保护提供了科学的理论指导,促进了黑颈乌龟经济养殖与物种保护的共同发展。

It is of great significance to study the genetic diversity of endangered species cultured population for the protection and utilization of germplasm resources.Mitochondrial COI gene was selected as the molecular marker of this study,and two cultured populations of Mauremys nigricans were compared and analyzed from sequence composition,haplotypes and genetic distance,and population historical dynamics.The results showed that the COI sequences of the two populations were 572 bp in length,with A+T content of 55.4%and G+C content of44.6%.The genetic diversity index of Guangdong population was higher than that of Guangxi population.Then,the two cultured populations shared 15 haplotypes,and the genetic distance within the Guangdong population(0.002~0.024)was higher than that within the Guangxi population(0.002~0.011),it can be seen that the Guangdong population has more abundant genetic variation.The neutral test results showed that the genetic differentiation among the populations reached a high level(Fst=0.20593),and the results of AMOVA analysis showed that the intra-population variations played a major role(79.4%)in the genetic differentiation of the two populations.Finally,the mismatch distribution and the results of the neutral test revealed that Guangxi population underwent population expansion,while the population did not accumulate nucleotide variation effectively during the expansion process.It was recommended that the breeding process avoid hybridization,strengthen gene exchange between different groups of the same species,and give priority to protecting haplotypes with low individual occupancy in the group.This study provides a scientific theoretical guidance for the genetic diversity conservation of Mauremys nigricans and promotes the development of economic culture and species conservation of them.