Molecular analysis of spinneret diversification in spiders

• Applicant: Dr. Matthias Pechmann
• Subject Area: Evolutionary Cell and Developmental Biology (Zoology)
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 537960802

With more than 51,000 extant species, spiders are one of the most specious groups of arthropods. Spiders belong to the Chelicerata, the sister group of the Mandibulata that comprise myriapods, hexapods and crustaceans. With their two tagmata (anterior prosoma and posterior opisthosoma) and their eight legs, spiders are easily recognizable among other arthropods. Spiders carry several specialized appendages on the segments of the opisthosoma. During embryogenesis, the opisthosomal segments two to five develop small limb buds. While the limb buds that develop on the second and third opisthosomal segment will develop into specialized breathing organs, the two more posteriorly located limb buds on the fourth and fifth opisthosomal segment develop into the spinnerets, modified appendages that are used to deposit silk threads. For many spiders, silk production is indispensable to life. Spiders use silk to capture pray, to build a nest, to communicate or to get distributed using air currents. Most spider females also invest large amounts of energy to build a silken cocoon to protect the eggs from desiccation and mechanical damage. Furthermore, some spider species use specialized silk to camouflage the cocoon, others use the compactness of the cocoon to carry it around and protect the offspring from predators. Different spider families often show a different number and morphology of the spinnerets. Interestingly, previous studies revealed the rudimentary nature of certain embryonic spinneret buds. However, the molecular mechanisms involved in the formation of the diversity of shapes or the number of spinnerets are largely unknown. In the here proposed study, we plan to use whole-transcriptome-sequencing (RNA-Seq) of spinnerets of different spider species, to identify relevant genes responsible for spinneret diversification. Subsequently, we will analyse the genes identified by this method for their site of expression and function. Overall, this study aims to identify the molecular factors and pathways that were recruited to change the number, identity and the morphology of the spider spinnerets, the structures that were fundamental to the evolution and adaptation processes of these fascinating animals.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr. Nikola-Michael Prpic-Schäper; Dr. Philipp Schiffer