Bringing a whole new meaning to the phrase ‘eye-catching’, Canadian scientists confirm male Pond Skater insects have evolved specifically shaped antennae to grapple and hold down resisting female mates, by their eye balls.
Using high-speed video cameras, Dr Abderrahman Khila and Professor Ehab Abouheif from McGill University, Montreal, observed the males using their hook-like antennae to pin down and successfully mate with reluctant females.
The study was undertaken after Professor Locke Rowe from the University of Toronto first speculated that the antennae seemed to perfectly match the contours of the female’s eyes and head.
Typical of most male organisms, the male Pond Skater is ready to mate multiple times a day. With the females being somewhat less keen, they have evolved the ability to store sperm and so only need mate once a week. This conflict of interests has affected the species’ evolution, with males evolving ways to restrain the females and the females evolving ways to resist; a “sexual arms race”.
Professor Rowe singled out the dll gene as responsible for the elaborate antennae growth. By reducing the gene’s activity using a technique known as RNA interference, the antennae were simplified, reducing or completely diminishing the male’s ability to copulate.
However, even when the antennae are fully functional, the males are only successful “10 percent of the time” says Rowe. “The females have become effective at dislodging males” as “unwanted mating increases the risk of a predator attacking”. It would seem the battle of the Canadian Pond Skater sexes is set to continue.
“The study gives us new insight into the evolution of novelty, and novelty is one of the most spectacular outcomes of the evolutionary process.”