While speculation about flash behaviour has existed for a while, Carleton PhD candidate Karl Loeffler-Henry published the first data that the adaptation is an evolutionary trait on July 28.
Studying this adaptation called “flash behaviour” was a collaborative process. The biology researcher worked alongside Tom Sherratt, a Carleton biology professor, and Changku Kang, a professor at Mokpo National University in South Korea.
When an animal is not moving, it hides its bright colours and is harder for predators to see, according to Loeffler-Henry. By exposing a bright flash of colour when moving, the prey confuses the predators by camouflaging their true colour. The bright flash of colour an animal shows when it starts to move is called a flash display.
“My thesis was that retraction of the [bright-coloured] display will mislead the predator into believing that the prey is no longer present,” Loeffler-Henry said. “So [predators] think that the colour of the flash display is the prey’s resting colour, and when that disappears, they think the prey is just gone.”
Carolina locusts, a species of grasshopper that can be found in southern Ontario, employ this anti-predation tactic. The locusts use bright black and yellow hind wings to create a flash display when they jump, according to Loeffler-Henry.
“If you’re walking down a bike path and you see them [jump], they actually look like butterflies. But you’ll notice when they land, they disappear and they very closely match the background,” Loeffler-Henry said.
Kang, a former Carleton post-doctoral fellow, said Sherratt created a computer simulation to test out Loeffler-Henry’s initial hypothesis. Loeffler-Henry said they used humans as the predators, who tried to find simulated prey both with and without the prey using flash displays.
The data from that portion of the research served as the first empirical evidence that flash displays could help prevent prey from being hunted, Loeffler-Henry said.
Loeffler-Henry’s next step was to see if there was a correlation between flash displays and body size. The research found a specific connection with larger insects as prey.
“Large insects are at a higher risk of predation because they’re inherently easier to find and they also represent a greater caloric reward,” Loeffler-Henry said. “So if we found that there was a correlation between the evolution of these hidden signals and body size in insects, it would be indicative that this anti-predation benefit was shaping selection.”
Loeffler-Henry studied 500 species of insects—four out of every five displayed a correlation between the evolution of flash displays and body size. That finding supported the idea that flash displays helped prey escape predators, Loeffler-Henry said.
Flash display research is a step towards understanding the colours and patterns seen on animals, Sherratt said.
“When I see a [small] moth now, I actually think in the back of my head that it is not likely to have any displays,” Sherratt said. “Or if I see a big [moth], I think that it’s going to probably have some eye spots or something to frighten me.”
Kang said he is currently trying to find out if flash displays work against predatory birds.
“The ideal way for testing [flash discoloration] is using real animals,” Kang said. “It was very difficult [to test this] because then we have to get real predators and real prey that show flash discoloration and we would have to probably manipulate the prey.”
While Carleton does not currently have the facilities for that testing, Kang said he is working to create a simulation for baby chickens. Kang said chickens are the easiest birds to train and raise for his research.
Loeffler-Henry said he will present his research at his PhD defence this September and hopes to keep researching why certain animals have specific patterns.
“It’s all good to look at biodiversity and just appreciate it—it’s beautiful and incredible,” Loeffler-Henry said. “But what we really want to do is [discover] why these patterns exist and provide evidence to that effect.”
Featured image provided.
