‘Butterflies emerged 85 million years ago when dinosaurs went extinct’

Krushnamegh Kunte is Associate Professor at the National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research. Speaking to Times Evoke, he explains how the little butterfly evolved:
The core of my research is studying how biodiversity evolved — in my research group’s focus, our larger question is how biodiversity, which underpins all biologic life, developed. Butterflies are an excellent system to study here — there are about 19,000 known species in the world, of which 1,400 occur in India. This high variation helps us understand how species were formed and morphological evolution happened or animals and plants grew so different from each other. Biodiversity is this big group of players in the entire drama of how ecosystems on Earth function — through butterflies, we explore how its various components fit, how traits evolved, etc.



Based on molecular evidence, we know life evolved from one common ancestor around three billion years ago. From then, evolution progressed, slowly to begin with — in the last billion years, we see very rapid diversification of life forms on Earth as multiple components clicked into place, including multicellularity or multiple cells coming together to form one organism, etc. Against this backdrop, we find all insects share a relationship with each other — they have a certain body plan, cellular functions, genetically encoded features (many have six legs, for instance) and the information of how these features are formed encoded in their genome.



Butterflies share many evolutionary features with insects. Butterflies are also specialised moths, the two separating from their sister group of insects 150 to 200 million years ago. Thereafter, moths themselves evolved significantly before butterflies emerged as a separate group about 85 million years ago, around when dinosaurs went extinct. All the characteristics butterflies have — including much more acute vision compared to moths who rely more on smell — grew thereon.

AN EMBATTLED MONARCH: The Monarch butterfly develops toxicity to ward off its predators — however, it now faces its milkweed feed being cleared by humans. Photo: iStock

Visual cues are extremely important for butterflies which explains why many are so attractive. Their appealing colours evolved to help them either evade predators or attract mates, dark colours developing to help butterflies maintain body temperature, being cold-blooded.

READING THE SIGNALS: The lovely colours of a butterfl y indicate a host of traits. Photo: iStock

Some species developed fascinating traits. Aposematism is a combination of two features — one is a defence against predators, like a chemical cover, some butterflies being toxic to birds, spiders, etc. These caterpillars feed on toxic plants which are difficult, if not deadly, for predators to digest. Being protected thus is an internal property — but butterflies with toxins then developed bright wing patterns to show predators they are dangerous, signalling the risk they bear. There are also mimetic butterflies — certain species are not toxic but have adopted the appearance of toxic species to evade predators. Mimic species only copy the signal and not the property of being toxic. A species which isn’t welldefended often copies one which is — we study how this evolved and how such behaviours and flight patterns grew.

MYSTERIOUS MORMON: Kunte’s group studies polymorphism in this species. Photo: iStock


When a butterfly flies, it’s actually displaying multiple signals at the same time — colour is one. Another is flight pattern — butterflies which are toxic or aposematic don’t face the same predation pressures as others. Being freer, their abdominal tissue grows heavier, causing a slight drag in flight with less twists and turns. Other species have a bigger thorax or flight muscle, which enables more powerful acceleration and flight, but these can’t invest as much in reproductive tissue in the abdomen as the former. Mimetic butterflies also start flying in that manner, slower, with fewer twists and turns. So, colouration is the first axis and mimicry the next one adopted by these species.



One of the species we study is the common Mormon found across India. Interestingly, recalling the social group this butterfly was named after, there is a single male form in the species, with multiple female forms. Our lab studies this quality of polymorphism or multiple forms — the females come in three forms, one non-mimetic male-like form and two females which mimic toxic butterflies. You can often find these caterpillars feeding on citrus plants like lemon or orange. When small, they discourage hungry birds by resembling bird waste, but as they grow older, the caterpillars turn green. This is just one species of butterfly — the vast panorama of these fluttering beings offers us fascinating insights about how life on Earth evolved over time.