基于线粒体tRNA^(leu)~COII和COI的贵州东方蜜蜂群体遗传分析

Population genetic analysis of Apis cerana in Guizhou based on mitochondrial tRNA^(leu)-COII and COI

【目的】明确贵州省东方蜜蜂群体的遗传结构和遗传多样性,掌握其遗传现状,为贵州省东方蜜蜂的遗传资源评价及保护利用提供参考依据。【方法】基于线粒体tRNA^(leu)~COII和COI片段对贵州省内19个采样点的1282群东方蜜蜂进行遗传分析,计算单倍型多样性(Hd)、平均核苷酸差异数(K)和核苷酸多样性(π)等遗传多样性指数,采用中性检验(Tajima's D和Fu's Fs)评估群体扩张情况,通过计算遗传分化系数(Fst)、构建系统发育进化树和分子方差分析评估其遗传分化,并开展环境因子相关分析以明确遗传分化的作用因子。【结果】贵州东方蜜蜂在线粒体tRNA^(leu)~COII片段上的Hd介于0.5421~0.9167,π介于0.00174~0.00527,K介于0.611~1.854,其中台江、雷山、麻江、罗甸、紫云、晴隆和威宁等7个采样点发生过群体扩张;在线粒体COI片段上的Hd介于0.5710~0.9109,π介于0.00109~0.00261,K介于0.874~2.084,其中松桃、江口、印江、台江、石阡、雷山、罗甸、紫云、黔西、晴隆和威宁等11个采样点发生过群体扩张。贵州东、西部东方蜜蜂群体间存在中度遗传分化(在tRNA^(leu)~COII片段上的Fst=0.04±0.02,在COI片段上的Fst=0.07±0.04),贵州西部东方蜜蜂群体内也存在中度遗传分化(在tRNA^(leu)~COII片段上的Fst=0.04±0.02,在COI片段上的Fst=0.07±0.03)。相关分析结果显示,贵州西部东方蜜蜂组群的遗传分化程度与海拔呈弱相关,但与温度、湿度等环境因子呈显著正相关。【结论】贵州省东方蜜蜂在线粒体tRNA^(leu)~COII和COI片段上的遗传多样性处于较高水平,主要归功于蜂群数量大和饲养方式较原始;贵州东方蜜蜂整体上呈现中度遗传分化,且西部东方蜜蜂组群内部的遗传分化程度较东部东方蜜蜂组群更高,主要与温度和湿度等环境因子密切相关,是其为适应所处环境而进化产生,而非海拔因素造成。

【Objective】The purpose of the study was to clarify the population genetic structure and genetic diversity of Apis cerana in Guizhou,to understand its genetic status,and to provide a reference basis for the evaluation,conservation and utilization of Apis cerana genetic resources in Guizhou.【Method】Genetic analysis was conducted on 1282 populations of A.cerana from 19 sampling sites in Guizhou based on mitochondrial tRNA^(leu)-COII and COI fragments.Genetic diversity indexes such as haplotype diversity(Hd),the average nucleotide difference(K)and nucleotide diversity(π)were calculated.Tajima’s D and Fu’s Fs neutral tests were carried out to evaluate population expansion.Genetic differentiation was assessed by calculating the genetic differentiation coefficient(Fst),constructing phylogenetic evolutionary trees and molecular variance analysis,and environmental factor correlation analysis was carried out to clarify the role of factors in genetic differentiation.【Result】The Hd of A.cerana in Guizhou on the mitochondrial tRNA^(leu)-COII fragment ranged from 0.5421 to 0.9167,πranged from 0.00174 to 0.00527,and K ranged from 0.611 to 1.854,with colony expansions occurring in seven sampling sites,including Taijiang,Leishan,Majiang,Luodian,Ziyun,Qinglong,and Weining.On the mitochondrial COI fragment,Hd ranged from 0.5710 to 0.9109,πranged from 0.00109 to 0.00261,and K ranged from 0.874 to 2.084,with population expansion occurring at 11 sampling sites,including Songtao,Jiangkou,Yinjiang,Taijiang,Shiqian,Leishan,Luodian,Ziyun,Qianxi,Qinglong,and Weining.There existed moderate genetic differentiation(on tRNA^(leu)-COII fragment,Fst=0.04±0.02,on COI fragment Fst=0.07±0.04)between A.cerana populations in the eastern and western of Guizhou,and moderate genetic differentiation(on tRNA^(leu)-COII fragment,Fst=0.04±0.02,on COI fragment,Fst=0.07±0.03)within A.cerana populations in the western part of Guizhou.The results of correlation analysis showed that genetic differentiation of A.cerana colonies in western Guizhou was weakly correlated with altitude,but significantly positively correlated with environmental factors such as temperature and humidity.【Conclusion】The genetic diversity of A.cerana in Guizhou is at a high level in mitochondrial tRNA^(leu)-COII and COI fragments,which is mainly attributed to the huge population size and primitive rearing methods.Guizhou A.cerana as a whole show moderate genetic differentiation,and the degree of genetic differentiation within the western A.cerana populations is higher than that of the eastern A.cerana,which is mainly closely related to the environmental factors,such as temperature and humidity,and arises from their evolution to adapt to the environment they live in rather than due to altitudinal factors.