A groundbreaking study by the University of Arizona has revealed fascinating insights into the evolution of colour vision and signalling in animals. Published in Biological Reviews, the research traces the origins of colour vision back approximately 500 million years—long before the emergence of colourful fruits and flowers—highlighting the ancient role that colour plays in animal communication.
Professor John J. Wiens and his team analysed how colour vision developed across species, revealing two major functions of colour signals: warning signals used by toxic species to deter predators, and sexual signals that evolved to attract mates. This study not only unravels the evolutionary timeline of colour signalling but also poses intriguing questions about how animals perceive colour, suggesting directions for future research in animal behaviour and sensory biology.
Origins of colour vision: An ancient tool for animal communication
Professor John J. Wiens and his team from the Department of Ecology and Evolutionary Biology conducted an extensive analysis of the evolutionary timeline, exploring the role of “conspicuous colours” in animal and plant species. The study found that colours like red, yellow, orange, blue, and purple are crucial for communication within and between species. The researchers identified two main types of colour signals in animals:
- Warning signals: Evolving around 150 million years ago, warning signals are used by toxic species, such as venomous snakes and poison frogs, to deter predators.
- Mating signals: Evolving approximately 100 million years ago, sexual signals are used to attract mates, exemplified by the peacock’s vibrant tail display.
Professor Wiens highlighted the widespread nature of warning signals, noting that they are five times more common than sexual signals. This prevalence is due to the fact that animals using warning signals don’t require colour vision themselves; rather, the signal is meant for other species.
The study also revealed a “dramatic explosion” in both warning and sexual colour signals over the last 100 million years, largely driven by ray-finned fish in marine environments, and by birds and lizards on land.
Colour signalling in plants
In plants, colour serves two main purposes: aiding seed dispersal in fruits and facilitating pollen distribution in flowers. According to the study, colourful fruits emerged around 350 million years ago, while colourful flowers appeared roughly 200 million years ago.
Future implications for colour perception studies
This research not only sheds light on the evolutionary history of colour vision and signalling but also raises questions about the mechanisms that enable animals to perceive specific colours. Co-author Zachary Emberts suggests that further research into colour perception across species could enhance our understanding of this complex aspect of animal biology.
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