Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ, UK.
St John's College, University of Cambridge, Cambridge, CB2 3EJ, UK.
Nat Commun. 2022 Aug 9;13(1):4676. doi: 10.1038/s41467-022-32316-x.
Repeated evolution can provide insight into the mechanisms that facilitate adaptation to novel or changing environments. Here we study adaptation to altitude in two tropical butterflies, Heliconius erato and H. melpomene, which have repeatedly and independently adapted to montane habitats on either side of the Andes. We sequenced 518 whole genomes from altitudinal transects and found many regions differentiated between highland (~ 1200 m) and lowland (~ 200 m) populations. We show repeated genetic differentiation across replicate populations within species, including allopatric comparisons. In contrast, there is little molecular parallelism between the two species. By sampling five close relatives, we find that a large proportion of divergent regions identified within species have arisen from standing variation and putative adaptive introgression from high-altitude specialist species. Taken together our study supports a role for both standing genetic variation and gene flow from independently adapted species in promoting parallel local adaptation to the environment.
重复进化可以深入了解促进适应新环境或变化环境的机制。在这里，我们研究了两种热带蝴蝶——海伦娜凤蝶（Heliconius erato）和红肩美凤蝶（H. melpomene）——在安第斯山脉两侧的山地生境中的适应过程。我们从海拔梯度的横断面上测序了 518 个全基因组，发现了许多在高地（1200 米）和低地（200 米）种群之间存在差异的区域。我们在同种的重复种群中发现了反复的遗传分化，包括地理隔离种群的比较。相比之下，两个物种之间的分子平行性很小。通过对五个近亲的采样，我们发现物种内鉴定的大量分化区域是由等位基因频率变化和来自高海拔专化物种的适应性基因渐渗引起的。总之，我们的研究支持了遗传变异和来自独立适应物种的基因流在促进对环境的平行局部适应方面的作用。
