Sensory systems enable animals to perceive their worlds and make adaptive decisions for survival. Evolution has shaped animals with multiple sensory systems that fit their lifestyle and environment, to give them the information they need to enhance their survival and reproduction. However, finding out about the world outside is energetically expensive: it involves complex sensory systems to collect the information, and dedicated neural systems to process it. Therefore, the benefits of acquiring information need to be balanced against the costs of receiving and processing it. As a consequence, when environmental constraints (e.g. living in the dark) limit the usefulness of specific sensory modalities (e.g. vision), shifts in investment in different sensory modalities can occur. For example, naked mole-rat are blind and compensate this lack of vision with an Eimer's organ that provides them with extra-sensory abilities in mechanosensory perception. Although comparative studies between closely related species have identified potential trade-offs between sensory modalities, empirical evidence is urgently needed to help establish that these trade-offs occur, and if so, under what conditions. Indeed, since human activity is shifting animals' lifestyle to a more nocturnal lifestyle, it becomes increasingly important to know how animals’ sensory capabilities will change to perceive the world around them.
Using brain measures, the project established the putative trade-off between vision and olfaction across a range of diurnal insect species, and identified that hunting mode and could help to explain how this trade-off is resolved. I found that predatory insects tend to invest more in vision and less in olfaction compared to insect species foraging by other methods. Using an empirical approach, I also found that living in the dark can reduce not just investment in vision, but also the reduce the size of the brain itself. This empirical approach also provided insights into how natural selection acts on sensory and neural systems, and showed the speed with which changes in the brain occur, and the degree to which these changes are reversible.
