How the integration of phylogenetics and venomics resolves persistent challenges in evolutionary systematics and toxinology lessons from the spider kingdom

• Main Author: Lüddecke, Tim
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2023
• Subjects: ddc:630; Antarc*; Antarctica
• Online Access: https://jlupub.ub.uni-giessen.de//handle/jlupub/11207; http://nbn-resolving.de/urn:nbn:de:hebis:26-opus-159840; https://doi.org/10.22029/jlupub-10590

Spiders represent one of the most successful branches of metazoan life. Throughout their long-lasting evolutionary trajectory, spiders diversified into almost 50,000 species. They conquered all continents except antarctica and established themselves as predators in virtually all ecosystems. The invention of venom systems, that are present in all but one spider lineages, contributed significantly to their evolutionary success. Albeit research on spiders, referred to as Arachnology, is an old field of study, it is hampered by a variety of persistent challenges awaiting scientific resolution. A subset of four such challenges, relating to evolutionary systematics and toxinology, are of pivotal importance. First, the taxonomic status of many spiders, in particular within the mygalomorph infraorder, and their phylogenetics remains largely ambiguous. Secondly, knowledge on spider venoms is so far fully derived from selected taxa and biased towards the few medically significant or exceptionally large species. Third, the sheer diversity of spiders makes it rather difficult to select promising focal taxa for venom bioprospecting studies. Lastly, knowledge upon the evolutionary forces driving spider venom evolution remains in its infancy. Addressing these important issues via phylogenetic and venomic approaches is the scope of this work.Systematic ambiguity is addressed by using tarantulas (Theraphosidae) as a model group. In two experimental setups, a molecular phylogenetic study utilizing six sequenced genes plus a phylogenomic study on ca. 2,000 genes, the first phylogenetic trees for Theraphosidae are constructed. These recovered monophyly of Theraphosidae as a whole and supported validity of formerly questionable subfamilies Poecilotheriinae, Psalmopoeinae and Stromatopelminae. It clarifies the position of Brachionopus and Harpactirella and argues for paraphyly of Schismatothelinae. In a trait evolution analysis, this work finds that defensive hairs likely evolved convergently within neotropical tarantulas. To make ...