Venom evolution in robber flies: An integrative approach applying functional morphology in venomics

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Venom evolution in robber flies: An integrative approach applying functional morphology in venomicsVenoms have convergently evolved in most lineages of the animal kingdom. The single protein components of venoms, called toxins, likely evolved from only a few protein families that generally show normal physiological function in each lineage. Venoms are crucial assets for the evolutionary fitness of species securing ecological and evolutionary success being used for defense, predation, competition and communication. Despite the suggested impact on evolutionary processes, venom evolution, but also the biology of venomous taxa, are poorly understood. Further, the function and evolution of venom delivery systems remains unclear for many venomous taxa.Among the economically important flies, the most prominent predatory fly group is Asilidae (robber flies). Robber flies are reported since the 19th century to predate on much larger, even venomous arthropods that are paralyzed immediately. These observations led to early assumptions that robber flies utilize strong neurotoxins in their venom arsenal. However, until today it remains unknown which toxins are expressed and in which of the two thoracic and labial glands. It remains further unclear, how gland morphology varies within robber flies and if all have labial glands.Our project idea integrates for the first time functional morphology based on synchrotron micro-CT and venomics to provide a better understanding of the evolutionary processes leading to such an unusual organ system in robber flies and possibly insects in general. It is integrated in a current PhD project Comparative venom evolution of robber flies, Doktorandenförderplatz Leipzig, using transcriptomics and proteomics to address the question if characteristic toxins are depending on more and less specific predation.The first goal of the present complementary morphological project is to assess the general variation in gland morphology between selected robber fly species, which represents a new aspect since a comparative approach has not been attempted so far. Further the labial glands are in stronger focus, it could well be that labial glands function like accessory glands as described in snakes, which is a complete novel idea.Main questions are:How do the paired thoracic and labial glands vary between species regarding shape and spatial arrangement?Are specific structures like musculature facilitating the process of venom injection? How does the venom gland system work?Is a different biology of robber flies, in particular the specialization to hunt on hymenopterans, linked to gland morphology?Do we find significant differences of labial glands between the robber fly species and if so are they linked to results of the transcriptomics?