Coevolutionary patterns between coloration and diel activity in moths

Anti-predator coloration is part of a key survival strategy in animals, often coevolving with behavioural traits such as diel activity. While previous studies have explored the link between conspicuous sexual signals and diurnality, the association between defensive coloration and diel activity remains unresolved. Here, we investigate the coevolutionary relationship between anti-predator coloration and diel activity in moths, a diverse clade with variable colour and activity patterns. Using a dataset of 322 moth species, we classified coloration of each species as cryptic or conspicuous and diel activity as diurnal, nocturnal, crepuscular or both day and night active ('All'). We applied phylogenetic comparative methods to assess evolutionary transitions between these traits. Our findings suggest that moths ancestrally exhibited cryptic coloration and nocturnality. Conspicuous coloration was more frequent in diurnal species, supporting an evolutionary association between daytime activity and being conspicuous. Transitions between nocturnal and diurnal activity occurred predominantly through an intermediate All state, particularly in cryptic species. Cryptic diurnality also evolved in some lineages, possibly driven by specific ecological factors such as when thermoregulatory needs are high. These findings provide insights into the interplay between diel activity and anti-predator coloration, with implications for understanding correlated evolution between these two traits.