Convergent genetic architecture underlies social organization in ants: Formica selysi Genome sequencing. Formica selysi

Complex adaptive polymorphisms are common in nature, but what mechanisms maintain the underlying favourable allelic combinations? The convergent evolution of polymorphic social organization in two independent ant species provides a great opportunity to investigate how genomes evolved under parallel selection. Here, we demonstrate that a large, non-recombining ‘social chromosome’ is associated with social organization in the alpine ant Formica selysi. This social chromosome shares architectural characteristics with that of the fire ant Solenopsis invicta, but the two show no detectable similarity in gene content. The discovery of convergence at two levels – the phenotype and the genetic architecture associated with alternative social forms – points at general genetic mechanisms underlying transitions in social organization. More broadly, our findings are consistent with recent theoretical studies suggesting that suppression of recombination plays a key role in facilitating coordinated shifts in co-adapted traits.

自然界中复杂适应性多态性（complex adaptive polymorphisms）普遍存在，但究竟何种机制维持了其背后的有利等位基因组合？两个独立演化的蚂蚁物种中多态性社会结构的趋同演化，为探究基因组在平行选择压力下的演化路径提供了绝佳研究机遇。本研究证实，高山蚁（Formica selysi）体内存在一段大型且不发生重组的“社会染色体（social chromosome）”，其与该物种的社会组织结构紧密关联。该社会染色体与红火蚁（Solenopsis invicta）的社会染色体具有相似的结构特征，但二者在基因内容上未检测到任何相似性。这一在表型层面以及与替代社会形式相关的遗传架构层面均发现趋同演化的现象，揭示了社会结构转变背后的通用遗传机制。从更广泛的视角而言，本研究结果与近期理论研究的结论一致，即重组抑制在推动共适应性状的协同转变过程中扮演关键角色。