
With 18,000 known butterfly species worldwide, it's no surprise scientists haven't fully figured out their relationships. Recently, a team of researchers developed the most comprehensive butterfly evolutionary map, incorporating 35 times more genetic data and triple the number of classifications compared to previous models. As Fast Company noted, the result is not only informative but also visually striking.
The research, published in Current Biology, utilized genetic data from 207 butterfly species, representing 98 percent of butterfly tribes (the category above genus). Directed by Akito Kawahara from the Florida Museum of Natural History and Marianne Espeland from the Alexander Koenig Research Museum in Germany, the study combined genetic information and fossil records to map the evolutionary history of butterflies and determine when various species branched off from their ancestors.
Espeland et al., Current Biology (2018)Visualizing millions of years of evolution in one family tree is no small feat. Each prominent label around the edge of the circle represents a butterfly tribe, like Tagiadini, followed by the species included in the study, such as Tagiades flesus (the clouded skipper). Species are grouped by subgroup—here, Pyrginae (spread-winged skippers)—and color-coded by family—Hesperiidae (skippers).
At the heart of the diagram, the solid gray circle labeled K-PG boundary (Cretaceous–Paleogene boundary) marks the catastrophic extinction event that wiped out most of Earth's plant and animal species, including the dinosaurs.
Espeland et al., Current Biology (2018)The study affirms several hypotheses that butterfly experts had previously proposed, while disproving others. Butterflies are classified into seven distinct families, and although past studies suggested that butterflies emerged around 100 million years ago, this new research pushes the timeline back to roughly 120 million years ago. However, only a few early butterfly ancestors existed before the mass extinction event that erased the dinosaurs, after which the butterfly family tree rapidly diversified.
Swallowtail butterflies (the subfamily Papilioninae, shown in blue) were the first to branch off, making them a 'sister' group to all other butterflies. Skippers (Hesperiidae, in purple) likely followed, with nocturnal butterflies like the Hedylidae family (in gray) next. However, some species once believed to share common ancestry, such as swallowtails, birdwings, zebra swallowtails, and swordtails, do not. The timeline reveals that certain butterfly species evolved alongside the plants they feed on, or even with ants, forming mutually beneficial relationships.
