Many-eyed monsters: A unified framework for the function, ecology and evolution of duplicated visual systems.

• Applicant: Dr. Lauren Sumner-Rooney
• Subject Area: Sensory and Behavioural Biology ; Evolution, Anthropology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 460394678

The evolution of vision revolutionised animal biology, and eyes have evolved in a stunning array of diverse forms over the past half a billion years. We conventionally picture visual systems as a single pair of eyes, but many animal groups have more. Although it sounds radical, duplicated vision is found across the animal kingdom: many arthropods have both ocelli and compound eyes, while cnidarians, molluscs, and annelids boast highly multiplied visual units, and even vertebrates can have enigmatic parietal and ‘fourth’ eyes. This fascinating phenomenon represents only a tiny fraction of research effort in behaviour, neuroscience, evolution, and comparative morphology, and remains very poorly understood. This project will be the first attempt to define, study and compare duplicated visual systems within a unified framework. We aim to identify the fundamental functional relationships and evolutionary drivers that have produced the diversity we see in animal vision, to finally understand how many-eyed animals collect and use information about their environment, and to determine why this strategy has evolved so frequently. We will address four key questions;Where do duplicated visual systems occur, what shapes their key features, and how similar are they?How and why do animals collect visual information from multiple inputs? How do animals combine multiple streams of information from functionally identical and/or functionally distinct eyes? How do duplicated systems evolve over time and what drives their divergence? First, we will conduct an exhaustive survey of duplicated systems across the tree of life, constructing a matrix of quantified and objective metric to describe their numbers, arrangements and functional characteristics. This will be used to identify consistent trends and relationships that could reflect fundamental functional, ecological and evolutionary principles of duplicated vision. Second, we will determine how information is collected and integrated in systems with hundreds or thousands of identical visual units, through a combination of psychophysical experiments and morphological modelling in chitons and brittle stars. Third, we will study how animals combine multiple different streams of information from parallel eye pairs using spiders as a model. We will reconstruct visual scenes as viewed by different eyes, using computational modelling to identify functional divergence between eye pairs. We will behaviourally test how cue clashes are resolved, and thus how information is combined and prioritised between eyes. Finally, we will use phylogenetic comparative methods to reconstruct the evolution of highly divergent parallel systems in spiders from functionally similar ancestral homologs. Charting diversification both within and between eye pairs over 400Ma, in the context of major ecological shifts and geological events, will allow us to identify key drivers and constraints in the evolution of these complex systems.

• DFG Programme: Independent Junior Research Groups