Meeting Abstract
The visual systems of many animals, particularly those active during the day, are optimised for high spatial resolution. However, at night, when photons are sparse and the visual signal competes with higher levels of noise, high spatial resolution cannot be sustained since it is traded for the higher sensitivity required to see in dim light. High spatial acuity demands detectors and successive visual processing units whose receptive fields cover only a small area of visual space, in order to reassemble a finely sampled and well resolved image. However, the smaller the sampled area, the fewer photons can be collected, and thus the worse the visual sensitivity becomes – leading to the classical trade-off between sensitivity and resolution. Nocturnal animals usually resolve this trade-off in favour of sensitivity, and thus have lower spatial acuity than their diurnal counterparts. We have recently shown that in dim light nocturnal hawkmoths spatially sum information from neighbouring visual processing units, thus increasing sensitivity and reducing spatial resolution in their motion vision system. Here, we compare several hawkmoth species with different diel activity patterns, to study to what degree species with different sensitivity requirements trade-off spatial resolution in favour of sensitivity, and at which stages of their visual system this trade-off occurs.
