Big wings and sweet songs: The mating lives of Panama’s katydids
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When it comes to reproduction, animals will pull out all the stops to attract a mate. Sending out noisy mating calls, showing off colorful wings, inflating a throat pouch, and shaking a literal tailfeather all ensure that the next generation of a species happens. Some insects will go as far as making themselves look like an entirely different living thing—leaves.
Usually used as a means of camouflage, male katydids appear to use their leafy disguise to amplify mating calls and make themselves more attractive to the opposite sex. The findings are detailed in a study published today in the journal Proceedings of the Royal Society B, and offer one of the first demonstrations of how leaf mimicry enhances a male katydids’ sexual signals.
To shield themselves from predators, various species of katydids have evolved wings with structures that look like leaves. Panama’s leaf-masquerading katydids (Arota festae) will even change from green to hot pink in order to better mimic leaves. What’s been less clear to entomologists is whether or not these leaf-mimicking structures play a role in katydid mating.
This new study looked at a species called Viadana brunneri from Barro Colorado Island, Panama. To attract mates, katydids create songs by rubbing together specialized structures on their wings. In many tropical species like V. brunneri, the portion that mimics leaves makes up the majority of their wing’s surface area.
Previously, scientists believed physical adaptations for survival and for attracting mates can function in conflict with one another, particularly if they are physically connected. A male peacock’s flashy tail feathers may help it attract a female, but it also makes it easier for predators to find them. Male katydids, on the other hand, are able to use the acoustic properties of the structures that they use for defense to their reproductive advantage. They are a rare example of how an adaptation for self-defence and reproduction can work together without necessarily putting the animal in jeopardy.
The team performed a series of bioacoustic, behavioral, and biophysical experiments, showing that these leafy structures on their wings make them more attractive to females, while also helping conceal them. After removing the leafy portions of a male V. brunneri’s wings, the pitch became higher and the volume of their songs also changed. The team then played these calls for females who preferred the lower pitch calls from males with their leafy wing sections still intact.
While male katydids do all the singing, females indicate their interest by replying to the song with clicks. The insects produce short, sporadic and infrequent calls, possibly for only two seconds in a single night. They perform these calls in ultrasounds, which our ears can’t pick up. They also found that the leafy portions of the male katydid wing will vibrate to amplify their songs, making them more detectable to females.
“Our study provides a rare example of natural and sexual selection acting in harmony, producing traits that simultaneously improve survival and mating success,” Dr. Benito Wainwright, a study co-author and evolutionary biologist at the University of St Andrews, said in a statement. “We are now extremely excited to start exploring how such an interesting interaction evolved in katydids.”
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