Data from: The devil is in the details: genetic variation in introduced populations and its contributions to invasion

The influence of genetic variation on invasion success has captivated researchers since the start of the field of invasion genetics 50 years ago. We review the history of work on this question and conclude that genetic variation—as surveyed with molecular markers—appears to shape invasion rarely. Instead, there is a significant disconnect between marker assays and ecologically relevant genetic variation in introductions. We argue that the potential for adaptation to facilitate invasion will be shaped by the details of genotypes affecting phenotypes, and we highlight three areas in which we see opportunities to make powerful new insights. (i) The genetic architecture of adaptive variation. Traits shaped by large-effect alleles may be strongly impacted by founder events yet more likely to respond to selection when genetic drift is strong. Large-effect loci may be especially relevant for traits involved in biotic interactions. (ii) Cryptic genetic variation exposed during invasion. Introductions have strong potential to uncover masked variation due to alterations in genetic and ecological environments. (iii) Genetic interactions during admixture of multiple source populations. As divergence among sources increases, positive followed by increasingly negative effects of admixture should be expected. Although generally hypothesized to be beneficial during invasion, admixture is most often reported among sources of intermediate divergence, supporting the possibility that incompatibilities among divergent source populations might be limiting their introgression. Finally, we note that these details of invasion genetics can be coupled with comparative demographic analyses to link genetic changes to the evolution of invasiveness itself.

自50年前入侵遗传学（invasion genetics）领域创立以来，遗传变异对生物入侵成功的影响始终是研究者们聚焦的核心议题。
本文梳理了该问题相关研究的发展历程，并得出结论：通过分子标记（molecular marker）手段检测到的遗传变异，似乎极少对入侵过程产生塑造作用。与之相悖的是，在物种引入过程中，分子标记检测手段与生态相关的遗传变异之间存在显著的脱节现象。
我们认为，助力入侵的适应性演化潜力，将由影响表型的基因型细节所决定；据此，我们提出三个有望取得突破性新发现的研究方向：
(i) 适应性变异的遗传架构（genetic architecture）。由大效应等位基因（large-effect allele）调控的性状，可能会受到奠基者事件（founder event）的强烈影响；但在遗传漂变（genetic drift）较强的情境下，这类性状又更易响应选择压力。大效应基因座（locus）或许与生物互作相关的性状有着尤为紧密的关联。
(ii) 入侵过程中暴露的隐性遗传变异（cryptic genetic variation）。由于遗传与生态环境发生改变，物种引入过程极有可能揭示此前被掩盖的遗传变异。
(iii) 多重源种群基因混合（admixture）过程中的遗传互作。随着源种群间分化程度提升，基因混合的效应将呈现先正后负的递增趋势。尽管学界普遍假设基因混合有助于物种入侵，但现有研究中，基因混合现象多出现于分化程度中等的源种群之间，这支持了以下可能性：高度分化的源种群间存在生殖不相容性，可能会限制其基因渐渗（introgression）。
最后，我们提出，可将入侵遗传学的上述研究细节与比较种群统计分析（comparative demographic analyses）相结合，从而将遗传变化与入侵性本身的演化过程直接关联起来。