Wang Da, Shi Xiaoqin, Liu Deguang, Yang Yujing, Shang Zheming
State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling 712100, Shaanxi, China.
College of Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi, China.
Insects. 2020 Feb 11;11(2):117. doi: 10.3390/insects11020117.
Host plant affinity and geographic distance can play critical roles in the genetic divergence of insect herbivores and evolution of insect biotypes, but their relative importance in the divergence of insect populations is still poorly understood. We used microsatellite markers to test the effects of host plant species and geographic distance on divergence of two biotypes of the English grain aphid, (Fabricius). We found that clones of from western provinces (i.e., Xinjiang, Gansu, Qinghai and Shaanxi) had significantly higher genetic diversity than those from eastern provinces (i.e., Anhui, Henan, Hubei, Zhejiang and Jiangsu), suggesting their differentiation between both areas. Based on genetic diversity and distance estimates, biotype 1 clones of eastern provinces showed high genetic divergence from those of western provinces in many cases. Western clones of also showed higher genetic divergence among themselves than eastern clones. The Mantel test identified a significant isolation-by-distance (IBD) effect among different geographic populations of , providing additional evidence for a critical role of geography in the genetic structure of both biotypes. Genetic differentiation (i.e., ) between the two biotypes was low in all provinces except Shaanxi. Surprisingly, in our analyses of molecular variance, non-significant genetic differentiation between both biotypes or between barley and wheat clones of was identified, showing little contribution of host-plant associated differentiation to the divergence of both biotypes in this aphid. Thus, it is highly likely that the divergence of the two biotypes involved more geographic isolation and selection of some form than host plant affinity. Our study can provide insights into understanding of genetic structure of insect populations and the divergence of insect biotypes.
寄主植物亲和力和地理距离在植食性昆虫的遗传分化及昆虫生物型的进化中可能起着关键作用，但它们在昆虫种群分化中的相对重要性仍知之甚少。我们使用微卫星标记来测试寄主植物种类和地理距离对麦长管蚜两种生物型分化的影响。我们发现，来自西部省份（即新疆、甘肃、青海和陕西）的麦长管蚜克隆的遗传多样性显著高于来自东部省份（即安徽、河南、湖北、浙江和江苏）的克隆，这表明这两个地区之间存在分化。基于遗传多样性和距离估计，在许多情况下，东部省份的生物型1克隆与西部省份的克隆表现出高度的遗传分化。西部的麦长管蚜克隆之间也比东部克隆表现出更高的遗传分化。Mantel检验确定了麦长管蚜不同地理种群之间存在显著的距离隔离（IBD）效应，为地理因素在两种生物型的遗传结构中起关键作用提供了额外证据。除陕西外，所有省份中两种生物型之间的遗传分化（即）都很低。令人惊讶的是，在我们的分子方差分析中，未发现两种生物型之间或麦长管蚜的大麦和小麦克隆之间存在显著的遗传分化，这表明寄主植物相关分化对该蚜虫两种生物型的分化贡献很小。因此，两种麦长管蚜生物型的分化很可能涉及更多的地理隔离和某种形式的值选择，而非寄主植物亲和力。我们的研究可以为理解昆虫种群的遗传结构和昆虫生物型的分化提供见解。
