Butterflies are among the most diverse and beautiful insects on Earth, with about 19,000 species1. But where did they come from and how did they evolve?
A new study by an international team of researchers has shed some light on these questions by creating the largest butterfly tree of life ever assembled.
The evolution of butterflies from moths
TAUSEEF MUSTAFA/AFP via Getty Images
The study, published in the journal Nature Ecology and Evolution2, used DNA from more than 2,000 species representing all butterfly families and 92% of genera to estimate the evolutionary history of butterflies and infer their movements through time, as per ScienceDaily.
The researchers also compiled a database of the host plants and geographic distributions of butterflies, using field guides, museum collections, and online sources.
The results showed that butterflies originated from a group of moths that started flying during the day rather than at night about 100 million years ago.
This coincided with the emergence of nectar-rich flowers that had co-evolved with bees.
By switching to a diurnal lifestyle, these moths were able to exploit a new ecological niche and diversify into many forms.
The first butterflies were likely legume-eating caterpillars that fed on plants such as beans and peas. They belonged to a group called Hedylidae, which still exists today and is sometimes called the "American moth-butterflies" because they resemble both moths and butterflies.
The biogeography of butterflies
The study also revealed where the first butterflies originated and how they spread across the globe, as per Phys.org.
The researchers found that butterflies first appeared somewhere in central and western North America 100 million years ago. From there, they expanded into South America and then into other continents.
The researchers identified six major dispersal events that shaped the global distribution of butterflies.
For example, about 50 million years ago, a group of butterflies called Nymphalidae colonized Africa from South America via Antarctica, which was then warmer and connected to both continents. Nymphalidae is now the largest butterfly family, with more than 6,000 species.
Another example is the colonization of Australia by butterflies about 40 million years ago.
The researchers found that this happened independently by three different groups of butterflies: Papilionidae (swallowtails), Pieridae (whites and yellows), and Lycaenidae (blues and coppers).
These groups adapted to the unique flora and fauna of Australia and diversified into many endemic species.
The study is not only a major contribution to the understanding of butterfly evolution but also a valuable resource for conservation efforts.
By knowing the evolutionary relationships, host plants, and geographic ranges of butterflies, researchers can identify the most threatened and diverse groups and regions and prioritize them for protection.
The study also highlights the importance of fossils for calibrating molecular clocks and estimating evolutionary timescales.
The researchers used 11 rare butterfly fossils as anchors for their tree of life. Without these fossils, they would not have been able to date the origin and diversification of butterflies with confidence.
Finally, the study showcases the power of collaboration among scientists from different disciplines and countries.
The researchers involved in this project came from dozens of institutions across the world and shared their expertise, data, and specimens to create a comprehensive picture of butterfly evolution.
