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The world’s greatest jousting competitions can be found in some rotting trees in the New Zealand bush, where hordes of males compete for the opportunity to mate. Knights are not humans but New Zealand giraffe lice, an insect with a spear-like nose. The largest males smash each other until the other either retreats or unexpectedly falls out of its shell.
Competition is particularly fierce as male giraffe lice come in staggering sizes: The largest male lice are 30 times larger than the smallest. From a human perspective, it would be like having a friend the size of two adult giraffes combined.
As male lice grow, their snouts grow disproportionately, suggesting that the largest males use relatively more energy to use their enormous heads. Some biologists have theorized that these exaggerated traits are what they call honest indicators of how fit the animal is as a potential mate or competitor; under this logic, a weak deer wouldn’t have the energy needed to maintain massive antlers.
But an article published in the magazine on Friday Functional Ecology She reports that the largest New Zealand giraffe lice actually use relatively less energy than their smaller-nosed relatives, thanks to an energy-saving anatomical hack.
Ummat Somjee, an evolutionary biologist at the Smithsonian Tropical Research Institute in Panama and author of the paper, originally studied leaf-footed insects to understand how much energy the beetles expend on their bulky hind legs.
One day, Dr. Somjee came across a rotting log in the jungles of Panama. joust bits. Dr. “It was like a little war zone in the log,” Somjee said. (The Panamanian type is depicted in the tweets embedded below.)
Dr. Somjee learned that these lice have an even weirder cousin, the New Zealand giraffe louse. The huge gap between male adult New Zealand giraffe lice made the species an ideal candidate for investigating the energy costs of various snout sizes.
It reached out to Chrissie Painting, a behavioral ecologist at the University of Waikato in New Zealand and author of the study, who began studying insects in 2009. Dr. Painting by Dr. He took Somjee to the secret collection point. He calls it the “bug city”.
If a New Zealand giraffe louse is surprised, it will throw itself from a tree. Dr. Painting held an ice cream bowl under the tree to collect the lice in bulk, waved his hand, and watched the lice rebound into the bowl at the same time.
Dr. Returning to Painting’s lab, the researchers measured the metabolic rates of plant lice. They placed the beetles in sealed glass syringes—their long bodies were custom-made for tubes—and measured their oxygen depletion at rest. They also placed the bits on small treadmills to measure the energy spent in a fast trot. Both results revealed that the larger bits used less energy per gram of tissue than the smaller bits. In other words, 30 small bits use much more energy than the largest 30 small bits.
These results may seem confusing – wouldn’t a pole-headed male louse use a lot more energy? The researchers decapitated the lice, dried the heads in an oven and placed them in a solution to digest living tissue, but retaining the cuticle, an inert hard tissue.
They found that larger male lice have noses and legs that contain more cuticles and less metabolically active tissue than smaller males. Dr. “This is a really cheap way to grow,” Somjee said. In fact, the largest males, smallest males, and females devote approximately the same percentage of their noses to soft, energy-consuming tissue.
Since no other insect has such a large size, the researchers compared their metabolic data with a number of other insect species. The pattern they found in their data was consistent across species, with larger bits using relatively less energy per gram of tissue.
Douglas Emlen, a biologist at the University of Montana who was not involved in the research, says the new paper confirms the long-held theory that exaggerated weapons are honest traits; for example, a bigger nose means a stronger bit.
But the new research also shows that guns are disproportionately costly for younger men, said Dr. Emlen.
“We all focus on really big boys,” he said. “But the important thing is whether the little guys can emulate it.” They can’t, he adds, which makes a big nose an honest sign of a louse’s bulky physique.
Adult lice do not grow. Dr. “If you come out as a little man, there’s no going back,” Painting said. So the smallest lice have developed an alternative mating strategy to compensate for their stump sniffers: They sneak under larger males to mate with females. But they are still not as successful as their larger rivals, and at the same time die younger, Dr. He said picture.
Medium-sized lice also have a rough road, being too small for jousting and too large to sneak in.
Dr. “There is nothing fair about nature,” Emlen said. “The rich get richer and the poor get poorer.”
Unfortunately, insects with short snouts really look smaller than two lice.
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