In a new tree of life, researchers have explained how butterflies developed and colonized the planet.

The world's largest butterfly tree of life was meticulously built by scientists, who found that the first butterflies appeared 100 million years ago in Central and North America.

North America was divided in two at this time by a seaway dividing the east and west as the supercontinent Pangaea was disintegrating. On this portion of the continent's western side, butterflies first appeared.

Currently, there are thought to be 20,000 different species of butterflies, and they can be found everywhere but Antarctica.

Although scientists were aware of when butterflies first appeared, they were still unaware of where they came from and what they initially ate.

Akito Kawahara, curator of lepidoptera (butterflies and moths) at the Florida Museum of Natural History, led the team of researchers who sequenced 391 genes from roughly 2,300 butterfly species from 90 nations, or 92% of known genuses, to create the new butterfly tree of life.

Data from many sources was combined by the researchers into a single publicly accessible database. To ensure that the branching points of their tree of life matched the time period of branching revealed by fossils, they selected 11 rare butterfly fossils as a benchmark. In a statement, Kawahara stated, "It's the most challenging study I've ever been a part of, and it took a massive effort from people all over the world to complete."

The research, which was published on May 15 in the journal Nature Ecology & Evolution, revealed that butterflies descended from nocturnal herbivorous moths approximately 101.4 million years ago. According to this, the first butterflies appeared in the middle of the Cretaceous, alongside dinosaurs.

Butterflies spread across what is now South America once they evolved. Some of them relocated to Antarctica, which at the time was still connected to Australia and significantly warmer. The two landmasses divided as they reached Australia's northernmost point, a process that started some 85 million years ago.

The butterflies then traveled through what is now Russia 75–60 million years ago, across the Bering Land Bridge, a land link that previously connected Russia and North America. The Middle East, Southeast Asia, and the Horn of Africa were next on their list of destinations. Around 60 million years ago, they even traveled to India, a remote island at the time. Surprisingly, for 45 million years at the edge of the Middle East, the expansion of butterflies stalled for unidentified reasons until eventually moving into Europe at 45–30 million years ago. According to Kawahara, the fact that there are fewer butterfly species in Europe today than in other regions of the world is a reflection of this hiatus.

According to an examination of 31,456 records of host plants for butterflies, the earliest insects consumed plants in the legume family. Nearly every ecosystem has legumes, but the majority of them lack strong compounds that protect them against insect feeding. These characteristics, according to scientists, may have led the butterflies to continue eating legumes for millions of years.

Although butterflies now consume multiple plant families, the majority still only consume one plant family. The majority of the species today eat only one plant family, primarily the wheat and legume families. Interestingly, the genesis of butterflies and the most recent common ancestor of legumes both occur around 98 million years ago.

According to a statement from co-author Pamela Soltis, a curator at the Florida Museum, "the evolution of butterflies and flowering plants has been inextricably intertwined since the origin of the former, and the close relationship between them has resulted in remarkable diversification events in both lineages."