A walk through a forest can be a bewildering experience. The whole forest appears to be running wild with insects of varied colours, hues and behaviours. Many of these traits appear to be deployed in defense against visually-hunting predators such as birds and lizards. Evolutionary biologists have long puzzled over the factors that determine when animals evolve to deter predators either through striking visual displays or by hiding in plain sight (i.e., camouflage). A global experiment, published today in the research journal Science, indicates when one antipredator strategy is more effective over another in helping insects survive potential predatory attacks.
Dr. Iliana Medina from the University of Melbourne, Australia, and Dr. William Allen from the Swansea University, United Kingdom, led a global experiment across six continents using more than 15,000 artificial prey in three different colour patterns—a classic warning pattern of orange and black, a dull brown that blends in, and a novel, potentially warning bright blue and black pattern. These artificial prey models were deployed in forest areas across the world, where natural predators presumably encountered them and decided either to attack and eat or avoid them. Findings of this experiment reveal that when it comes to deterring predators, the ecological context is crucial and several factors play a part in determining whether a camouflage or warning strategy works best.
Lead author Dr. Allen commented, “For a long time, scientists have wondered why some animals use one defence over the other – and the answer turns out to be complicated. The predator community, prey community and habitat are all influential. This helps explain why we see camouflaged and warning-coloured animals all over the world.”
The study discovered that the predator community had the biggest impact on which prey colour was most successful against predators in a given habitat. The results supported the notion that when predators compete intensely for food, they are more likely to risk attacking prey that might be dangerous or distasteful. Hence, camouflage worked best in areas with a high predation pressure.
However, being cryptic did not always work. In bright environments, camouflaged prey was more visible than in darker environments and was attacked more than prey with classic warning colours. Familiarity with prey using different colour strategies was also important. In places where cryptic prey was abundant, hiding became less effective, as predators were presumably better at locating camouflaged prey. The results showed, overall, how multiple ecologically relevant mechanisms determine which strategy is evolutionarily more advantageous under specific circumstances.
Dr. Medina added, “Some questions in ecology involve such a wide range of variables that only global collaboration and replication could bring us closer to understanding how nature works. It was a pleasure to work with such a diverse group of colleagues who made this research possible”.
The Indian work in this experiment was conducted by Viraj Nawge, Arka Pal, Archan Paul, and Sarika Baidya, under the guidance of Dr. Krushnamegh Kunte of the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru. “This work gave us young PhD students an invaluable opportunity to participate in a global experiment. It helped us experience the true excitement of doing fundamentally important research into the amazing antipredator strategies that animals use to defend themselves against the omni-present predators,” said Viraj, echoing a sentiment shared by all other students involved in the Indian experiments.
Dr. Kunte was pleased with the research experience that his students gained and the results of the Indian experiments. “It is rare that we gain deep insights into how animals, especially insects that make up a significant proportion of the known species of organisms on earth, evolve such effective antipredatory strategies over a broad swath of habitats. Defensive colouration of prey insects evolves specifically in the contexts of the light environment and predators that potentially attack and eat insects in these environments. This work sheds light on these evolutionary strategies in a unique way,” quipped Dr. Kunte, adding, “To be able to gain such insights while guiding curious and hard-working students was a great pleasure.”
The researchers say their findings will now help build a better understanding of the evolution and global distribution of these common, visual antipredatory strategies in animals. This will be especially fruitful in tropical regions that display a wide variety of insect prey, predators, and habitats.
Citation of the research paper:
Medina, I., A. Exnerová, K. Daňková, et al., W. L. Allen. 2025. Global selection on insect antipredator coloration. Science, 389:1336–1341.
This work includes as authors the following present and former NCBS researchers: Sarika Baidya, Viraj Nawge, Arka Pal, Archan Paul, and Krushnamegh Kunte.
DOI: https://doi.org/10.1126/science.adr7368
Press contacts for the global study:
Dr. Iliana Medina: iliana.medina@unimelb.edu.au
Dr. William L. Allen: w.l.allen@swansea.ac.uk
Press contact for the Indian work:
Prof. Krushnamegh Kunte
National Centre for Biological Sciences
Tata Institute of Fundamental Research
Bengaluru, India
Phone: +91 9483-525-925
Email: krushnamegh@ncbs.res.in
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