Abstract：
Identifying the genetic architecture underlying adaptive traits is exceptionally challenging in natural populations. This is because associations between traits not only mask the targets of selection but also create correlated patterns of genomic divergence that hinder our ability to isolate causal genetic effects. Here, we examine the repeated evolution of components of the auxin pathway that have contributed to the replicated loss of gravitropism (i.e. the ability of a plant to bend in response to gravity) in multiple populations of the Senecio lautus species complex in Australia. We use a powerful approach which combines parallel population genomics with association mapping in a Multiparent Advanced Generation Inter-Cross (MAGIC) population to break down genetic and trait correlations to reveal how adaptive traits evolve during replicated evolution. We sequenced auxin and shoot gravitropism-related gene regions in 80 individuals from six natural populations (three parallel divergence events) and 133 individuals from a MAGIC population derived from two of the recently diverged natural populations. We show that artificial tail selection on gravitropism in the MAGIC population recreates patterns of parallel divergence in the auxin pathway in the natural populations. We reveal a set of 55 auxin gene regions that have evolved repeatedly during the evolution of the species, of which 50 are directly associated with gravitropism divergence in the MAGIC population. Our work creates a strong link between patterns of genomic divergence and trait variation contributing to replicated evolution by natural selection, paving the way to understand the origin and maintenance of adaptations in natural populations.
摘要：
在自然种群中，识别适应性性状的遗传结构异常具有挑战性。这是因为性状之间的关联不仅掩盖了选择的目标，而且还产生了基因组差异的相关模式，这阻碍了我们分离因果遗传效应的能力。这里,我们研究了生长素途径成分的重复进化，这些成分导致了澳大利亚Seneciolautus物种复合体多个种群中重力性的重复丧失（即植物响应重力而弯曲的能力）。我们使用一种强大的方法，将平行种群基因组学与多亲代交叉（MAGIC）种群中的关联映射相结合，以分解遗传和性状相关性，以揭示适应性性状在复制进化过程中如何进化。我们对来自六个自然种群（三个平行发散事件）的80个个体和来自两个最近发散的自然种群的MAGIC种群的133个个体中的生长素和芽引力相关基因区域进行了测序。我们表明，MAGIC种群中对重力的人工尾巴选择会重现自然种群中生长素途径的平行发散模式。我们揭示了一组55个在物种进化过程中反复进化的生长素基因区域，其中50个与MAGIC种群的引力性发散直接相关。我们的工作在基因组差异模式和性状变异之间建立了强有力的联系，有助于自然选择的复制进化，为理解自然种群适应的起源和维护铺平了道路。
