The ecology and evolution of dynamic colour signalling

<p dir="ltr">Change is an inherent part of the visual experience of animals. The most profound source of dynamicity is found within visual scenes and is caused by self-movement, the motion of objects, and changes in the broader visual panorama. Such fluidity is ever-present and fundamentally affects how visual events are perceived. However, we do not yet fully understand or account for the effects of dynamicity when it comes to visual ecology. The overarching aim of my thesis was to examine the complex matter of dynamicity in visual ecology, with a focus on the effects of flashy appearances as a model context. In the first chapter of my thesis, I reviewed the various effects, causes and potential consequences of visual dynamicity in animal interactions. This synthesis articulates the temporal dimension of signalling, along with the spatial and spectral dimensions, as one of the main attributes comprising the visual experience of animals. Further, it summarises the perceptual significance of dynamic visual effects, explores the drivers of perceptual variation in these effects across animals, and finishes with novel predictions for our understanding of visual signal ecology and evolution. In the following four chapters, I concentrated on one of the identified gaps in knowledge: the breath of visual effects of flashing colour patterns in animals. In Chapter 2, I used a novel touchscreen setup and wild Eurasian bluetits (<i>Cyanistes caeruleus</i>) to test how dynamic colour flashing in moving “prey” stimuli affects the birds’ ability to peck them. Chapter 3 is a natural history paper that looks into the mate search behaviour of males in the Common grass yellow butterfly (<i>Eurema hecabe</i>) and sets the contexts for my research on dynamic signals with this species in the following chapters. In Chapter 4, I conducted a field-based behavioural experiment testing how the moving and flashing of conspecifics affect male mate detection in <i>E. hecabe</i>. Finally, in Chapter 5, I did a series of lab-based experiments with the same species, testing their preferences for different nectar flower signal attributes and how they affect signal detectability in challenging viewing conditions. I found that visual flashing is a conspicuous feature that increases the likelihood of being detected. In Chapter 4, the flashing appearance of fluttering butterflies proved an important cue for locating potential mates. However, we could not repeat the effect in a laboratory-based experiment (Chapter 5) where we tested the detectability of a flashing, nectar source simulating stimulus in a visually noisy environment. Further, although flashing features during locomotion render animals conspicuous when they move, my findings in Chapter 2 support that flashing colour patterns during fast movement have the potential to help prey deflect predator attacks. My thesis findings show that visual signals with dynamic features can potentially bear many perceptual effects. Specifically, I found that flashing colour patterns in animals can increase their detectability to conspecifics, but likely also to viewers such as predators. I also found that the conspicuous flashes in moving animals can mitigate predation risk by making predator attacks less accurate at close range.</p>