Evidence for speciation underground in diving beetles (Dytiscidae) from a subterranean archipelago

Most subterranean animals are assumed to have evolved from surface ancestors following colonisation of a cave system, however very few studies have raised the possibility of ‘subterranean speciation’ in underground habitats (i.e. obligate cave-dwelling organisms (troglobionts) descended from troglobiotic ancestors). Numerous endemic subterranean diving beetle species from spatially-discrete calcrete aquifers in Western Australia (stygobionts) have evolved independently from surface ancestors; however, several cases of sympatric sister species raises the possibility of subterranean speciation. We tested this hypothesis using vision (phototransduction) genes that are evolving under neutral processes in subterranean species and purifying selection in surface species. Using sequence data from 32 subterranean and five surface species in the genus Paroster (Dytiscidae), we identified deleterious mutations in: long wavelength opsin (lwop), arrestin 1 (arr1), and arrestin 2 (arr2) shared by a s...

学界普遍认为，绝大多数地下动物均是在定居洞穴系统后由地表祖先演化而来，但仅有极少数研究提出了地下生境中存在地下物种形成（subterranean speciation）的可能性，即专性洞穴栖息生物（troglobionts）由洞栖祖先演化而来。来自西澳大利亚州空间隔离钙结岩含水层的多种特有地下潜水甲虫（stygobionts，地下水生生物）均独立起源于地表祖先；但多例同域姐妹物种的存在，提升了地下物种形成的可能性。本研究利用视觉相关的光转导（phototransduction）基因验证了这一假说：这类基因在地下物种中以中性进化过程演化，而在地表物种中则受纯化选择作用。本研究基于棒脚牙甲属（Paroster，龙虱科Dytiscidae）32个地下物种与5个地表物种的序列数据，鉴定出长波长视蛋白（lwop）、抑制蛋白1（arr1）与抑制蛋白2（arr2）中存在由一类[原文内容截断]共有的有害突变。