Meeting Abstract
The evolutionary relationships among the orders of Arachnida has proven challenging despite the availability of a vast amount of genetic data. The placement of pseudoscorpions remains uncertain due to a phylogenetic artefact, long branch attraction, which leads to statistically inconsistent relationships among the arachnid orders. Analyses including a broad sampling of pseudoscorpion taxa spanning each of superfamily support the placement of pseudoscorpions as the sister group to scorpions. The sequential removal of basally branching lineages from analyses artificial increases the branch length of the order’s basal branch, leading to support for the placement of pseudoscorpions as sister to the parasitiform ticks and mites due to long branch attraction. Alternative classes of phylogenetic data are a potential solution for reconstructing relationships where sequence data have not achieved topological stability. Rare genomic events serve as a data class to determine the relationship between pseudoscorpions and the rest of Arachnida. We investigated the signature of shared duplicated genes as phylogenetic characters as indication for a relation between pseudoscorpions with the arachnopulmonates (spiders, scorpions, and their allies), which are inferred to have undergone an ancient whole genome duplication. We sequenced the first developmental transcriptome of the pseudoscorpion Conicochernes crassus to investigate the incidence of duplicated genes shared by the arachnopulmonates. Our transcriptomic data show that pseudoscorpions retain many duplicated genes across a variety of disparate gene families. Analysis of gene trees recovered topologies consistent with a single shared genome duplication with arachnopulmonates, suggesting a close relationship with the pseudoscorpions.
