A sweeping new study sheds light on butterflies' origins

ARI SHAPIRO, HOST:

Where do butterflies come from? Well, obviously caterpillars, but what about way, way before that? Where did butterflies first emerge? A sweeping new study now gives us an answer. Here's science reporter Ari Daniel.

ARI DANIEL, BYLINE: Akito Kawahara remembers the moment his butterfly collection began. He was 8 years old, standing beside his dad in a neighborhood in Tokyo.

AKITO KAWAHARA: And this unusual brown butterfly sort of lands near the road. I was like, oh, my gosh. I've read about these things, but I've never caught one. So my hands were trembling. I had my butterfly net in my hand. I ran up to it, and I caught it.

DANIEL: Kawahara split his childhood between Tokyo and New York, where, later that same year, his dad secured a special tour of the insect collection at the American Museum of Natural History.

KAWAHARA: There was this picture of this family tree of butterflies. I remember there was a couple of question marks in different places - just looking at it, realizing that scientists at these museums still don't know these basic things. I'll never forget that day.

DANIEL: Kawahara went on to become the curator of butterflies and moths at the University of Florida, and those questions of where butterflies first emerged, how they evolved and spread across the world, have only grown in importance to him.

KAWAHARA: There's a lot of butterflies right now that are threatened, and understanding how these butterflies are related to each other - it serves as a framework to help us conserve them.

DANIEL: And conserve the flowers and plants that rely on butterfly pollination. So to piece together that family tree, Kawahara worked with close to 90 colleagues from six continents to collect DNA from all kinds of butterflies.

KAWAHARA: I felt like I was a kid all over again.

DANIEL: He nabbed a yellow sulphur butterfly right outside his office in Florida, but he went way farther than that - the Andes, the Amazon rainforest, the dry savannas of Mozambique, back to Tokyo. All he and his team needed was a tiny portion of one of each butterfly's six legs.

KAWAHARA: So it's not harmful, and oftentimes we can release the butterfly, and the butterfly's still OK.

DANIEL: The bulk of the butterflies they studied were pinned specimens in museum collections. All told, they analyzed the DNA from 92% of all butterfly groups, which allowed them to zero in on where butterflies began some hundred million years ago.

KAWAHARA: People had thought that butterflies originated somewhere in Asia, but we were surprised to find out that it's likely North or Central America.

DANIEL: Where they first fed on legumes. They then likely fluttered their way to South America, dispersing in waves across Asia, Australia, India, Africa and finally Europe, forming the kaleidoscope of 19,000 butterfly species we know today. This work's published in the journal Nature Ecology and Evolution. Adriana Briscoe, an evolutionary biologist at UC Irvine who wasn't involved in the research, says it'll be worth analyzing the few remaining groups of butterflies.

ADRIANA BRISCOE: These missing groups might help pinpoint exactly where in the Americas butterflies originated.

DANIEL: She has another reason for being excited about these findings.

BRISCOE: More than any other place in the world, butterflies were sacred to the ancient people of Mesoamerica. They were thought to be the souls of ancestors.

DANIEL: For Akito Kawahara, the ancestor who's front of mind is his dad, of course, who he told about this project right as it was beginning in 2014.

KAWAHARA: He told me, that's wonderful, and he wished me luck.

DANIEL: That was the last time they spoke. He died two days later. Kawahara says one way he remembers his dad is through his butterfly collection, which now has 20,000 specimens.

KAWAHARA: It's kind of like your diary. It's really touching.

DANIEL: Each butterfly is a memory for Kawahara, a moment in time where he can stand beside his dad once again. For NPR News, I'm Ari Daniel.

(SOUNDBITE OF MICHAEL JACKSON SONG, "BUTTERFLIES") Transcript provided by NPR, Copyright NPR.