Many prey animals, like the peacock butterfly, have eyes that dissuade predators from attacking. In a recent study, scientists from the and the Max Planck Institute for Chemical Ecology showed that the eyespots’ arrangement affects the survival of the prey. Eyespots have a greater deterrent potential when they appear to be staring directly at a predatory chick. The best deterrents are concentric circles that look like they’re making eye contact no matter what angle you look at them from.
In nature a matter of life and death
Visitors to an art gallery may be familiar with this sensation, where they feel as though the person who is depicted in the work is watching them or even following them throughout the space. Because the painter carefully focused on the subject’s pupils, the phenomenon is known as the “Mona Lisa effect,” after the most well-known portrait that exhibits it. Many fish and butterflies, among other species, have paired circular patches on their bodies that mimic eyes. “The Mona Lisa effect appears to be used by nature as well. However, it can be a matter of life and death in the animal kingdom. ” The Max Planck Research Group on Predators and Toxic Prey at the Max Planck Institute for Chemical Ecology in Jena, Germany, is led by Hannah Rowland.
The directions of the gaze matters
Hannah Rowland and John Skelhorn from Newcastle University designed a behavioral experiment with freshly born domestic chicks that were educated to attack imitation moths for a mealworm reward in order to evaluate the Mona Lisa effect and rule out a general deterring impact of visible patterns. The artificial moths were three different types: one with “eyes” that looked to the left, one with “eyes” that looked to the right, and one with perfectly concentric circles; as a result, they appeared to gaze straight ahead or to one of the two sides. When the chicks had learned how to attack the prey, they were given one of the three types of artificial moths. The scientists then built tiny catwalks, called “chickwalks,” that either led straight to the food or came up from the side to their target.
The outcomes of the behavioral studies were clear-cut: “When the eyespots seemed to look to the left, the chicks came more warily from the left. When the eyes were moved to the right, chicks coming from that direction displayed a comparable level of concern. The chicks swiftly attacked the imitation moth and consumed the mealworm when they came at the artificial eyes from the opposite angle. Moths with concentric circular eyes were approached only very cautiously by chicks. ” The observations are summarized by John Skelhorn.
Chicks perceive eyespots as eyes
The chicks’ perception of the fake eyespots as eyes is supported by the behavioral data. “Similar to paintings that seem to maintain eye contact no matter where you are in the room, eyespots with concentric rings have the appearance of staring at prospective predators, like our chicks, from a variety of angles. “This likely also explains how diverse animals in nature independently evolved eyespots to effectively ward off predators,” Hannah Rowland concurs.
At the Max Planck Institute for Chemical Ecology in Jena, Hannah Rowland is the director of the independent Max Planck Research Group Predators and Toxic Prey. She focuses on predator-prey interactions because they have long been used as models to study adaptation and fitness in real environments and because they offer some of the best instances of parallel evolution. In order to answer these fundamental issues, Hannah Rowland and her team draw on techniques from computational biology, physiology, molecular and cell biology, and behavioral ecology. How can novel features emerge and spread throughout populations? How do qualities differ between populations or between people within populations? What conditions encourage and sustain trait diversity? Finding the ecological and evolutionary mechanisms that underlie interactions between species can be done by finding the answers to these questions. Additionally, they contribute to our understanding of the causes of local adaptability and biodiversity, as well as the responses of biological systems to environmental stressors.
