There is exciting news for butterfly enthusiasts. By studying 207 species of butterflies, scientists have created an evolutionary tree painting the detailed picture of butterfly relationships and evolution over time.
An international team of lepidopterists (people who study moths and butterflies) carried out DNA studies and carbon dating analysis to understand the age and characteristics of butterflies. By comparing and merging previous studies on butterflies (genome sequencing data), the researchers were able to create the new bigger and better evolutionary tree.
“We still have a long way to go, but this is the first comprehensive map of butterfly evolution,” said Akito Y. Kawahara, associate professor at the Florida Museum of Natural History in a release. “Lots of previous studies cover butterfly evolution on smaller scales — by locality or taxon — but surprisingly few have reached across the breadth of butterfly diversity.” Dr. Kawahara is the corresponding author of the paper published in Current Biology.
The report also supported previous studies that butterflies originated around 119 million years ago in the late Cretaceous period. After the mass extinction (65 million years ago), most of the butterflies diverged into many different groups.
The seven wonders
The butterfly species were placed in seven groups — Papilionidae, Hedylidae, Hesperiidae, Pieridae, Riodinidae, Lycaenidae and Nymphalidae.
“Our analyses support swallowtails (Papilionidae) as sister to all other butterflies, followed by skippers (Hesperiidae) and the nocturnal butterflies (Hedylidae) as sister to the remainder,” says the report.
The whites (Pieridae) were supported as sister to brush-footed butterflies (Nymphalidae), blues and metalmarks (Lycaenidae and Riodinidae).
Previously, swallowtails and birdwings were believed to have a common ancestor but the new study showed that they feed on different plants. “That tells us that butterflies and plants may have evolved together,” Dr.Kawahara added.
Mutualism with ants
They also studied the association of butterflies with ants. Some butterfly larvae secrete sugars that serve as a meal for ants and the ant in return protects the larva from other predators. This is a well-studied symbiotic relationship. The scientists report that most of the blue butterflies and hairstreaks and some of the metalmark butterflies exhibit this behaviour.
“This [evolutionary tree] is usually an ever changing ‘map’ of the ‘territory’ of nature. As new techniques are developed, we gain new insights. In the current paper, a larger data set than ever before has been used, comprising 207 out of 18,800 species of butterflies discovered so far. However, almost all the known tribes are represented, despite the small number of sample,” says Peter Smetacek, founder of the Butterfly Research Centre in Bhimtal, Nainital. “This is not the first time such a tree has been constructed, but it is the first time that such a complete tree has been constructed on genetic evidence.”
“We [India] have about one fifth of the known moths and butterflies represented in Indian collections (3,800 out of an estimated 20,000 species). The only way they could undertake the study was the fact that they have access to a good collection. We lack this in India,” explained Smetacek.
