Meeting Abstract
Two tribes of subterranean diving beetles have independently colonised ground water systems of the Australian desert, a habitat transition that was presumably driven by the contraction of surface water bodies during Miocene aridification of the Australian continent. These ‘stygofauna’ are now trapped within discrete calcrete aquifer pockets that have formed in paleodrainage valleys, resulting in one of the world’s most diverse radiations of subterranean dytiscid beetles. Species exhibit partial or fully regressed visual systems and are essentially blind. This unique study system enables regressive evolutionary processes to be studied in parallel at an unheralded comparative scale – approximately 100 species are now known from two related tribes (Bidessini and Hydroporini). Here we detail the exploration of insect vision genes for signatures of adaptive and neutral evolutionary mechanisms related to eye regression, largely within photoreceptor and eye pigment genes. The transcriptomes of five representative dytiscid beetle species (two surface and three subterranean) were used to design a customized set of RNA baits for hybrid-capture of vision genes and next generation sequencing using Illumina platforms. This methodological design permits the assessment of modifications in the genomic sequence of beetle vision genes at a much broader scale (cf. Sanger sequencing), enabling a higher number of both target species and genes to be simultaneously assessed relative to research time-investments. From a comparative phylogenetic perspective, the potential insights for an improved understanding of the genetic mechanisms underlying regressive evolution generally are thoroughly enticing.
