MSc Student
Advisor: Georg Brenneis

Unit for Integrative Zoology, Department of Evolutionary Biology
University of Vienna

The evolutionary history of the Euchelicerata (spiders, scorpions, mites and kin) is heavily debated due to considerable incongruities between phylogenetic hypotheses based on traditional (mostly external) morphology and those generated from molecular datasets. In the past decades, several comparative studies taking a closer look at the arthropod central nervous system (CNS) and its underlying architecture have produced comprehensive neuroanatomical datasets that can be analyzed against the background of competing phylogenetic hypotheses.

In this master’s thesis, I will investigate the expression of SIFamide, a highly conserved neuropeptide utilized by a small subset of neurons in arthropods, in the CNS of euchelicerates. In addition to providing the first detailed descriptions of SIFamidergic neurons in this diverse arthropod lineage, all taxa studied will be compared and checked for similarities and differences, with the aim to evaluate whether the neuronal patterns may provide additional support for any of the highly discussed hypotheses on euchelicerate phylogeny.

For data acquisition, the CNS of various euchelicerate taxa will be dissected, labeled via fluorescent immunohistochemistry and documented by confocal laser-scan microscopy. The emerging patterns of SIFamidergic nerve cell somata and their projections will be described and compared between the taxa investigated. Character state mapping of these patterns on competing phylogenetic hypotheses will be performed as a first step to assess whether they may be phylogenetically informative.