Caroline Chabou’s eyes light up when she talks about stink bugs. Like gemstones, they exist in a myriad of bright colors, including shiny blues, reds, oranges, leafy greens, and transparent colors studded with gold. They are members of the 40,000-species group of potato beetles, the family Coryptidae, one of the most species-rich branches of the vast order Coleoptera. “There are weevils, longhorn beetles and potato beetles,” she says. “It is precisely this trio that dominates beetle diversity.”
Entomologists at the University of Nebraska-Lincoln chavu He had long wondered why the life world was so biased toward beetles. Sturdy-bodied creatures make up about a quarter of all animal species. Many biologists have long wondered the same thing. “Darwin was a beetle collector,” Chabou points out.
![Despite their kaleidoscopic diversity, most beetles share the same three-part body structure. The insect can fold its wings like origami under protective forewings called elytra, allowing the beetles to squeeze into crevices in rocks and burrow into trees. Scientists say the beetle's knack for thriving in a wide range of microhabitats may also help explain its species richness.](https://cdn.arstechnica.net/wp-content/uploads/2024/04/beetle-anatomy-2-640x454.png)
Of the approximately 1 million named species of insects on Earth, approximately 400,000 are beetles. And that’s just the beetle we’ve described so far. Scientists typically report thousands of new species each year. So why are there so many beetle species? “We don’t know the exact answer,” Chabou says. But clues are emerging.
One hypothesis is that there are a lot of them because they have been around for so long. “Beetles are 350 million years old,” says evolutionary biologist and entomologist. duane mckenna from the University of Memphis, Tennessee. This is a very long time for existing species to speciate or split into new, distinct genetic lineages. In comparison, modern humans have only existed for about 300,000 years.
But just because a group of animals is old doesn’t necessarily mean that there are more species in that group. Some very old groups include very few seeds. For example, coelacanth fish have been swimming in the oceans for about 360 million years, reaching a maximum of about 90 species, but have since declined to the two species known to exist today. Similarly, the lizard-like reptile tuatara, which originated some 250 million years ago, is the only surviving member of a once globally diverse group of ancient reptiles.
Another possible explanation for why beetle species are so abundant is that, in addition to being old, beetles have unusual persistence. “They have survived at least two mass extinctions,” he says. Christian Bezaveza, postdoctoral fellow at the University of Minnesota. In fact, a 2015 study that used beetle fossils to investigate extinctions dating back to the Permian period 284 million years ago concluded: lack of extinction It may be at least as important as diversity in explaining beetle species richness. The authors hypothesize that, at least in the past, beetles have demonstrated a remarkable ability to shift their ranges in response to climate change, which may explain their resilience to extinction. There is.