Aphelinus rhamni breed:MCh05_Bj Raw sequence reads

Risks of post-introduction evolution in insects introduced to control invasive pests have been discussed for some time, but little is known about responses to selection or genetic architectures of host adaptation and thus about the likelihood or rapidity of evolutionary shifts. We report here results on the response to selection and genetic architecture of parasitism of a sub-optimal, low-preference host species by an aphid parasitoid, Aphelinus rhamni, a candidate for introduction against the soybean aphid, Aphis glycines. We selected A. rhamni for increased parasitism of Rhopalsiphum padi by rearing the parasitoid on this aphid for three generations. We measured parasitism of R. padi at generations two and three, and at generation three, crossed and backcrossed parasitoids from the populations reared on R. padi with those from populations reared on Aphis glycines and compared parasitism of both R. padi and Aphis glycines among F1 and backcross females. Aphelinus rhamni responded rapidly to selection for parasitism of R. padi. Selection for R. padi parasitism reduced parasitism of Aphis glycines, the original host of A. rhamni. However, parasitism of R. padi did not increase from generation two to generation three of selection, suggesting reduced variance available for selection, which was indeed found. We tested the associations between 184 single nucleotide polymorphisms (SNP) and increased parasitism of R. padi and found 28 SNP loci, some of which were associated with increased and others with decreased parasitism of R. padi. We assembled and annotated the A. rhamni genome, mapped all SNP loci to contigs, and tested whether genes on contigs with SNP loci associated with parasitism were enriched for candidate genes or gene functions. We identified 80 genes on these contigs that mapped to 1.2 Mb of the 483 Mb genome of A. rhamni but found little enrichment of candidate genes or gene functions.

昆虫引入以控制入侵害虫后的进化风险已被讨论一段时间，但对于宿主适应性选择响应或遗传架构的响应知之甚少，因此关于进化转变的可能性或速度亦所知有限。本文报道了对一种次优、低偏好的寄主物种——由蚜虫寄生蜂Aphelinus rhamni（作为大豆蚜虫Aphis glycines引入的候选者）对寄生选择和遗传架构的响应研究结果。通过将寄生蜂在Rhopalsiphum padi蚜虫上饲养三代，以提高其对该蚜虫的寄生率，我们选择了A. rhamni。在第二、三代中测量了R. padi的寄生率，并在第三代，将饲养在R. padi上的种群与饲养在Aphis glycines上的种群进行杂交和回交，比较了F1和回交雌性对R. padi和Aphis glycines的寄生率。Aphelinus rhamni对R. padi的寄生选择反应迅速。对R. padi的寄生选择降低了A. rhamni的原生宿主Aphis glycines的寄生率。然而，从选择第二代到第三代的R. padi寄生率并未增加，这表明可供选择的变异性减少，这一点确实得到了证实。我们测试了184个单核苷酸多态性（SNP）与R. padi寄生率增加之间的关联，并发现了28个与寄生率增加或减少相关的SNP位点。我们对A. rhamni基因组进行了组装和注释，将所有SNP位点映射到连续体上，并测试了与寄生相关的SNP位点所在的连续体上的基因是否富集了候选基因或基因功能。我们在这些连续体上识别了80个基因，这些基因映射到A. rhamni 483 Mb基因组中的1.2 Mb，但发现候选基因或基因功能的富集很少。