Even at night, some bees are still out there, watching you with their dark vision. Three genera of Central American bees—Megalopta, Megaloptidia, and Megommation—eschew the sunshine, colorful flora (and predatory birds), and prowl instead for the few flowers that bloom in the moonlight. Researchers in Panama caught thousands of these bees, trapping them on a bedsheet hung over a bright lamp, and collected their DNA. By comparing their genetic sequence to that of 15-million to 20-million-year-old bees encased in amber found in the Dominican Republic, they tracked how a gene for a protein in the eye called an opsin, which detects different wavelengths of light, has changed over the millennia. Just a few small spelling differences in the genetic code for that opsin made it better at detecting contrast than color, allowing these bees to morph from sunlit flower-flitters to buzz-by-night foragers 22 million years ago, the researchers report today in the Proceedings of the Royal Society B. But one genus of bees, a modern relative of Megalopta called Xenochlora, came back to the light 7.6 million years ago; maybe it was afraid of the dark.
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