Molecular Phylogenetics of the mygalomorph spider family Theraphosidae
Spiders are the most successful and diverse group of venomous arthropods and therefore represent an excellent model to study evolutionary patterns in invertebrate venom systems. Among spiders the mygalomorph family of Theraphosidae, commonly referred to as Tarantulas by the wider public, takes an outstanding position since they easily belong to the most prominent spiders on earth. That being said it is remarkably that the theraphosid evolutionary history still remains poorly understood since morphological based methods are commonly in use for this group and mostly provided controversial results so far. Therefore we aim in this project to establish molecular phylogenetic to phylogenomic approaches to recover the theraphosid tree of life and clarify the taxonomic status of key theraphosids. Secondly we aim to use this data to further study the evolution of different tarantula traits with strong emphasis on venoms. In our most recent study we provided a phylogenetic tree of theraphosid subfamilies based on six molecular markers and comprising ten of currently eleven accepted subfamilies. We recovered sound geographical clades and verified the monophyly of many theraphosid subfamilies whereas other recently questioned or invalid subfamilies (e.g. Poecilotheriinae and Schismatothelinae) were found to be strong supported and therefore should be treated as valid.
Lüddecke, T., H. Krehenwinkel, G. Canning, F. Glaw, S. Longhorn, R. Tänzler, I. Wendt, M. Vences (2018): Discovering the silk road: Nuclear and mitochondrial sequence data resolve the phylogenetic relationships among theraphosid spider subfamilies. Molecular Phylogenetics and Evolution 119: 63-70.
Exploring the skin poison of Salamandra
Salamanders of the genus Salamandra are widely spread across Europe, North Africa and the Near East. They are loosely grouped in two different groups (fire salamanders and alpine salamanders, six species in total) and adapted to very different environments. However they are also known to be poisonous since the antiquity: Members of Salamandra secrete or spray a potent skin poison from their poison glands which are distributed across their dorsal side. The skin poison is composed by multiple substances, ranging from biogenic amines and steroids to peptides and steroidal alkaloids referred to as samandarines. The latter have been subject to scientific studies between the 1860s and the 1970s, however several issues around samandarines remain unsolved. Besides a detailed understanding of samandarine modes of action against predators and especially pathogens, we are also lacking informations about samandarine biosynthesis and comparative samandarine profiles between species, sexes and life history phases of Salamandra. Another key component in amphibian skin poisons is represented by (antimicrobial) peptides, which are usually seen as part of the innate amphibian immune system but recently have been demonstrated to furthermore improve toxin delivery into predators, leaving them as a sophisticated chemical defense system on multiple scales. However we actually dont know anything about the peptides in the Salamandra skin poison. In face of the emerging pathogen Batrachochytrium salamandrivorans, which recently extirpated Salamandra populations in parts of Europe a detailed understanding of the skin poison as a main player in Salamandra anti-pathogen defense is urgently needed. We therefore aim in this project to understand the interspecific variation of bioactive components on i) the samandarine level and ii) the level of peptidomes/ proteomes. We apply combined approaches of next generation sequencing, proteomics, GC-MS, preparative HPLC and NMR to find new components and to understand the complex matrix of Salamandra skin poison in a biological context.