AsianScientist (Dec. 20, 2017) – In a study published in Frontiers in Ecology and Evolution, scientists in Singapore and Australia have discovered that the bright color patterns of beetles are for camouflage rather than for warding off predators.
Colors and patterns in nature are often used to attract mates, to scare off predators, or to blend in with the surroundings. Brighter colors and banded patterns are typically perceived as warning signs in the animal kingdom.
In this study, a team of researchers led by Dr. Eunice Tan at the Yale-National University of Singapore has discovered that the bright color patterns of leaf beetles are a form of camouflage. Previously, coleopterists—scientists who study beetles—thought that the bright colors of the beetles functioned as a deterrent signal to predators.
Tan and her team spent 17 months photographing live beetles in 32 locations across four Australian states. She then compared each beetle’s coloration to the color of the leaf it was found on. Taking into account the evolutionary relationship between the different beetle species, Tan discovered that different species of beetles had color patterns similar to those of their host plants.
This suggests that the colorations have a camouflaging effect, rather than serving a predator-deterring (aposematic) function. This camouflage effect was particularly pronounced in beetles which fed on multiple types of plants, as they had to blend into many different environments.
“It was long thought that conspicuous color patterns served to advertize the distastefulness of an organism to its predators. However, we have found that this cannot be the sole reason that conspicuous color patterns developed in leaf beetles,” Tan said.
Through her field studies, Tan also observed the impact of ecological factors on the evolution of different beetle species’ coloration patterns. She found that both larger and smaller beetle species in her sample had similar levels of color contrast against their backgrounds.
However, the larger beetle species were more likely to be found in darker environments than their smaller cousins, suggesting that they were employing a hiding strategy against predators, despite having similar conspicuous coloration to their smaller cousins. An ecological property, the brightness of the environment, was therefore a potential factor influencing the evolution of beetle coloration.
Taken together, the findings of this study point to a complex suite of factors driving natural selection, such as types of predators and host plant choice, which affect the evolution of colouration in leaf beetle, Tan explained. She postulated that the variety of anti-predator strategies in leaf beetles that she has found may explain their successful spread into a variety of habitats.
The article can be found at: Tan et al. (2017) The Role of Life-History and Ecology in the Evolution of Color Patterns in Australian Chrysomeline Beetles.
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Source: Yale-NUS College; Photo: Pixabay.
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