Data from: The predictability of genomic changes underlying a recent host shift in Melissa blue butterflies

Despite accumulating evidence that evolution can be predictable, studies quantifying the predictability of evolution remain rare. Here, we measured the predictability of genome-wide evolutionary changes associated with a recent host shift in the Melissa blue butterfly (Lycaeides melissa). We asked whether and to what extent genome-wide patterns of evolutionary change in nature could be predicted (1) by comparisons among instances of repeated evolution, and (2) from SNP $\times$ performance associations in a lab experiment. We delineated the genetic loci (SNPs) most strongly associated with host use in two L. melissa lineages that colonized alfalfa. Whereas most SNPs were strongly associated with host use in none or one of these lineages, we detected a ~two-fold excess of SNPs associated with host use in both lineages. Similarly, we found that host-associated SNPs in nature could also be partially predicted from SNP $\times$ performance (survival and weight) associations in a lab rearing experiment. But the extent of overlap, and thus degree of predictability, was somewhat reduced. Although we were able to predict (to a modest extent) the SNPs most strongly associated with host use in nature (in terms of parallelism and from the experiment), we had little to no ability to predict the direction of evolutionary change during the colonization of alfalfa. Our results show that different aspects of evolution associated with recent adaptation can be more or less predictable, and highlight how stochastic and deterministic processes interact to drive patterns of genome-wide evolutionary change尽管已有越来越多的证据表明演化具备可预测性，但量化演化可预测性的相关研究仍较为稀缺。本研究以近期发生寄主转换的梅利莎蓝蝶（Lycaeides melissa）为研究对象，量化了其全基因组演化变化的可预测性。本研究旨在解答两个问题：自然界中的全基因组演化变化模式是否可被预测，以及可被预测的程度如何——其一，通过重复演化实例间的比较实现预测；其二，基于实验室实验中获得的单核苷酸多态性（Single Nucleotide Polymorphism, SNP）与适合度性状的关联结果实现预测。我们在两个已定植于紫花苜蓿的梅利莎蓝蝶支系中，鉴定出与寄主利用方式强相关的遗传位点（SNP）。尽管大多数SNP仅在其中一个支系中与寄主利用方式呈强相关，或完全未呈现相关关联，但我们检测到在两个支系中均与寄主利用相关的SNP数量较预期高出约两倍。类似地，我们发现自然界中与寄主相关的SNP，也可通过实验室饲养实验中获得的SNP与适合度性状（存活率与体重）的关联结果得到部分预测。但二者的重叠程度，即可预测性的高低，均有所降低。尽管我们能够在一定程度上预测自然界中与寄主利用强相关的SNP（通过平行演化比较及实验室实验结果），但我们几乎无法预测该蝶类定植紫花苜蓿过程中的演化变化方向。本研究结果表明，与近期适应性演化相关的不同演化维度，其可预测性存在高低差异；同时也揭示了随机过程与确定性过程如何相互作用，共同塑造全基因组演化变化模式。