October

Analysis of more than 450 snake species finds many use striking colours to advertise danger to predators   Researchers at University of Galway have found that venomous snakes are significantly more likely than non-venomous species to have colours that stand out against their natural surroundings. Animals use colour for many purposes, including camouflage, attracting mates and warning predators. For some animals, however, being conspicuous can be a survival strategy. Wasps, poison dart frogs and coral snakes are among the best-known examples of species whose bold colours warn potential predators that they are dangerous. While warning colouration has been studied in individual species and small groups of animals, it has remained unclear whether conspicuous colouration is generally associated with venom across a large number of snake species. Published in the Journal of Animal Ecology, the researchers examined more than 450 snake species from around the world, comparing how their colouration appears against the natural environment in which they live. The team compared snakes in their natural habitats by sourcing thousands of photographs through the citizen science platform iNaturalist. They examined whether venomous species were more visually distinct from their surroundings than non-venomous species, in particular looking at red and yellow colouration, two colours commonly associated with warning signals in the animal world. The study confirmed that while many venomous snakes are not brightly coloured, a large number have evolved distinctive colours and patterns. It is further evidence of a link between venom and warning colouration, suggesting that the two traits may have evolved together in some snake species and that being highly visible may have been the survival strategy and warning of danger to potential predators. Amy Duclaux from University of Galway’s School of Natural Sciences and a lead researcher on the project, said: “Our findings show that venomous snakes stand out from their natural background more than non-venomous species, supporting the idea that warning colouration has evolved to signal danger to potential predators. “Rather than hiding from predators, some venomous snakes appear to advertise that they're dangerous. Their striking colours likely evolved as warning signals that discourage attacks before they happen. “We also found that red and yellow colouration is particularly effective at helping snakes stand out against their natural background, suggesting these colours play an important role in visual signalling." Dr Kevin Healy, Head of the Macroecology Lab at the University’s School of Natural Sciences, said: “Citizen science initiatives such as iNaturalist are transforming ecological research by providing images of animals in their natural habitats at a scale that would otherwise be impossible for individual research teams to achieve. Museum collections allow us to measure colour accurately, but photographs taken in the wild are essential for understanding how those colours appear in the environments where they evolved." The findings offer new insight into the evolution of warning signals, suggesting that for some venomous snakes, conspicuous colouration may be less about hiding from predators and more about making sure they are seen. The research also highlights how citizen science and large-scale image datasets are transforming the study of evolution across the animal kingdom. The full study in the Journal of Animal Ecology is available at https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.70351  Ends