The evolutionary mechanisms optimizing neural circuit structure and function for skylight navigation across insect species

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Insects are the most diverse group within the animal kingdom and provide both important ecological and economic benefit. For successful hunting, foraging, or dispersal, most free-living insects rely on considerable navigation skills, for which they use different visual stimuli, like celestial bodies and skylight polarization. Despite great morphological diversity of insect eyes, recent data revealed that their retinal mosaics show remarkable similarities across species. While systematic morphological characterization has identified retinal detectors for polarized skylight in virtually all insects analyzed, it remains unknown whether specification of these structures and their underlying neural circuitry are in fact evolutionarily conserved. Moreover, it is unknown how their structure (connectivity) and function (computation) are adapted to the diverse ecological niches of different insect species.In this proposal, we are planning to test three hypotheses:(1) The molecular mechanism for specifying polarized skylight detectors is conserved across insects(2) Variations in the transcription factor network adapt this detector system to species-specific demands(3) Gene products expressed specifically in downstream circuit elements shape evolutionarily conserved neural networks. We will use the molecular genetic tools available in Drosophila in combination with different bioinformatics methods, to compare regulatory sequences, transcription factor binding sites, transcription factor networks, and gene expression profiles across insects. These experiments will reveal evolutionarily conserved mechanisms as well as species-specific adaptations behind the formation of neural circuits for insect skylight navigation.