Species evolve more than twice as fast at poles as in tropics: study

Species evolve more than twice as fast at poles as in tropics: study

Coral reef ecosystem at Palmyra Atoll National Wildlife Refuge. Species diversity in the tropics is far greater than that found at the poles, but scientists have found that the rate of speciation for fish is much faster in polar regions. Image by Jim Maragos / U.S. Fish and Wildlife Service. Picture a healthy, tropical coral reef. Lionfish, parrotfish, and clownfish dart through cerulean waters, swimming over a veritable rainbow of corals. Now picture the Arctic and Antarctic oceans. If you struggle to come up with anything besides a cold, dark abyss, where very little ever happens ecologically or evolutionarily, you’re not alone. But, you’d also be wrong. The tropics are home to a dazzling array of biodiversity, the temperate zones less so, with the poles often evoking words like “barren” and “desolate.” Biologists describe this continuum as the latitudinal diversity gradient, with species densities lowest in the Arctic and Antarctic, and highest around the equator. This concept has long guided our thinking about Earth’s biodiversity, informing widely held assumptions that the tropics have higher biodiversity because species form there faster. That’s why new research, published in the journal Nature, is so shocking to the scientific community. The clichéd image of the Arctic and Antarctic oceans is of evolutionarily starved ecosystems. Scientists have now shown this to be far from the truth, at least among fish species. Photo credit: JEROME LESSARD/PHOTOGRAPHER on Visual Hunt / CC BY-NC When researchers compared the evolutionary relationships of more than 30,000 fish species, they found…

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