Project One: Spider microbiome
Bacterial symbioses and the animal microbiome are increasingly acknowledged as critical factors contributing to animal adaptation and evolution. Therefore, within the context of Argiope bruennichi’s range expansion, we are investigating potential differences in the microbiome of the central and range-expanding populations. Preliminary DNA barcoding analysis confirms the presence of various microbes within all organ systems of the spider, alongside an exciting discovery of an unknown and dominant bacterium within all spiders tested. To augment this emerging story, we are looking for an interested student to histologically section spider tissue to identify intra- and extracellular microbes within different organ systems.
Research field: microbiology, microbial ecology
Methods: histology, Transmission Electron Microscopy (TEM)
Start date: Any time; tissues are dissected, fixed, and ready for processing and analysis
Supervision: Monica M Sheffer, Carsten Müller, Tim Urich, Gabriele Uhl
Project Two: At the interface of development and mating strategies: Immature mating in the cannibalistic widow spider Latrodectus geometricus
This project targets the unusual strategy of mating with immature females from a morphological point of view. Immature females of L. geometricus can mate successfully already a few days before their final moult. This is surprising since mating normally requires a final moult. In order to investigate the development of female reproductive organs until the final moult, we will investigate female genitalia at different developmental stages using histology and Micro-CT. Additionally, we will process genitalia of differently aged females of a related species Parasteatoda tepidariorum that is not known to perform immature mating. The comparison might reveal interspecific differences in female genital development that have led to different male reproductive strategies.
Research field: reproductive biology, ontogeny
Methods: Histology, Micro CT
Start date: May/June 2018
Supervision: Lenka Sentenska, Yael Lubin, Gabriele Uhl
Project Three: Plasticity of higher-order brain centers in jumping spiders
Jumping spiders are renowned for their high cognitive abilities and outstanding vision. We have shown for females of the jumping spider Marpissa muscosa, that the environment influences the volumes of specific brain areas. The proposed thesis topic will tackle the question, whether the brains of male jumping spiders are also affected. You will compare male M. muscosa which grew up in four different environments: a physically enriched treatment, a socially enriched (group-) treatment, a deprived environment and wild caught spiders. 3D-reconstructions of brain areas will be conducted and their volumes compared - across the treatment groups and with our data on females.
Research field: neuromorphology
Methods: Micro CT scanning, 3D reconstruction
Supervision: Philip OM Steinhoff, Gabriele Uhl
Project Four: Functional morphology of male mating structures in Mantophasmatodea
Mantophasmatodea (heelwalkers) is the most recently described insect order. The wingless predators occur in Southern Africa; until now, 19 species have been described. Males possess very complex genital structures to transfer sperm to the female. So far, only the cuticular parts of dissected specimens have been investigated and some structures used for taxonomy. The project aims to reveal the morphology of male reproductive structures within the body, and investigate how the complex copulatory organ fits into the female genital opening when protruded. All inner reproductive structures (testes, accessory glands) will be investigated for the first time in Mantophasmatodea and compared to other insect taxa.
Research field: reproductive biology, functional morphology
Methods: Micro CT, histology, dissection, AMIRA-reconstruction
Starting date: Any time
Supervision:Monika Eberhard, Gabriele Uhl
Project Five: Mating structures in Mantophasmatodea
Copulation in Mantophasmatodea can take up to three days. During that time, males cling to the female’s back and do not feed or drink, while females readily prey and take up water. The project raises the question whether male cerci, which are asymmetrically formed, facilitate this prolonged genital coupling by fitting into the openings of female apodemes on the subgenital plate. Here, several heelwalker species will be investigated to identify the shape and possible fit of both structures.
Research field: reproductive biology, functional morphology
Methods: microphotography, shape analysis, dissection
Starting date: Any time
Supervision:Monika Eberhard
Project Six: Chemosensory sensilla in spiders
Although it is obvious from behavioral observations that spiders can smell and taste, how they do it has been little explored. Their candidate sensilla differ strongly from those known for insects. We will investigate if the sensilla differ in their setup depending on whether they come in contact with the substrate or not. We hypothesize that the former sensilla are used to taste and the latter to smell and expect differences in their internal morphology. Apart from inter-individual assessment of sensilla diversity, we also aim to compare sensilla between different spider families. In the end, these data will contribute to our understanding of the evolution of sensory systems in arthropods.
Research field: sensory systems
Methods: histology, Transmission Electron Microscopy (TEM)
Start date: Any time; tissues are dissected, fixed, and ready for processing and analysis
Supervision: Carsten Müller, Gabriele Uhl