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 earliest 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 while the supercontinent Pangaea was disintegrating. On this
portion of the continent's western edge, butterflies first appeared.
Currently, there are thought to be
20,000 different species
of butterflies, and they can be found everywhere save 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 that 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
around 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 now 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 eating. 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 now consume
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 approximately 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."
