Data from: Positive selection on sociobiological traits in invasive fire ants

The fire ant Solenopsis invicta and its close relatives are highly invasive. Enhanced social cooperation may facilitate invasiveness in these and other invasive ant species. We investigated whether invasiveness in Solenopsis fire ants was accompanied by positive selection on sociobiological traits by applying a phylogenomics approach to infer ancient selection, and a population genomics approach to infer recent and ongoing selection in both native and introduced S. invicta populations. A combination of whole-genome sequencing of 40 haploid males and reduced-representation genomic sequencing of 112 diploid workers identified 1,758,116 and 169,682 polymorphic markers, respectively. The resulting high-resolution maps of genomic polymorphism provide high inference power to test for positive selection. Our analyses provide evidence of positive selection on putative ion channel genes, which are implicated in neurological functions, and on vitellogenin, which is a key regulator of development and caste determination. Furthermore, molecular functions implicated in pheromonal signaling have experienced recent positive selection. Genes with signatures of positive selection were significantly more often those over-expressed in workers compared with queens and males, suggesting that worker traits are under stronger selection than queen and male traits. These results provide insights into selection pressures and ongoing adaptation in an invasive social insect and support the hypothesis that sociobiological traits are under more positive selection than traits related to non-social traits in such invasive species.

红火蚁（Solenopsis invicta）及其近缘类群具有极强的入侵性。增强社会合作或许可促进此类及其他入侵蚁类的入侵能力。本研究通过系统基因组学（phylogenomics）方法推断古老选择事件，并利用群体基因组学（population genomics）方法分析本地与入侵红火蚁（Solenopsis invicta）种群的近期及持续选择过程，以此探究红火蚁属（Solenopsis）入侵蚁类的社会性生物学性状是否伴随正向选择。本研究对40只单倍体雄蚁开展全基因组测序，对112只二倍体工蚁进行简化基因组测序，分别鉴定出1,758,116个和169,682个多态性标记。由此获得的高分辨率基因组多态性图谱，为正向选择检测提供了强劲的推断效力。分析结果显示，参与神经功能调控的推定离子通道基因，以及调控发育与品级分化的关键调节因子卵黄原蛋白（vitellogenin），均呈现正向选择信号。此外，涉及信息素信号传导的分子功能也经历了近期的正向选择。相较于蚁后与雄蚁，呈现正向选择特征的基因在工蚁中显著更易出现过表达现象，这表明工蚁的性状相较于蚁后和雄蚁受到更强的选择压力。本研究结果为入侵性社会性昆虫的选择压力与持续适应性演化提供了新的研究视角，同时支持了此类入侵物种的社会性生物学性状较非社会性相关性状受到更强正向选择的假说。