University scientist joins international team to sequence butterfly genome

The international study has revealed the key behind the butterfly’s unusual ability to mimic other butterflies.

A first for science, the genome-sequencing work is the product of an international group of researchers, dubbed the Heliconius Genome Consortium, who examined the genome of the Postman butterfly (Heliconius melpomene), a well-known species that lives in the Peruvian Amazon. Using that data as a guide, they then examined the genetic make-up of two other closely-related butterfly species – Heliconius timareta and Heliconius elevatus.

These butterflies are found in the tropical and sub-tropical regions of the Americas, from the Amazon basin to Texas and has been studied by scientists since the Victorian era.

All three species were selected for the study because they each share similar colour patterns on their wings as a way to ward off predators.

The Consortium’s surprising finding, as described in a paper published on 16 May in leading scientific journal Nature, is that the various species all look similar because they share the parts of their DNA that deal with colour patterns.

The genetic sharing between species, researchers believe, is the result of hybridisation. Considered extremely rare, particularly in animals, hybridisation occurs when insects of two different species interbreed in the wild.

The resulting hybrid offspring share traits with both mother and father. Though often considered an evolutionary dead-end, hybrids occasionally interbreed with a parent species, in the process introducing new genes that can help populations adapt to new or changing environments.

Professor Richard ffrench-Constant said: “The classical definition of a species is defined by two animals that can't breed successfully. Here we have shown this definition to be faulty as rare matings can allow large sections of the genome to pass between species. This allows for useful traits such as colour patterns to be swapped wholesale between separate species. This changes the way we need to think about how species evolve.”

A total of 80 researchers in 32 research universities and institutions from eight countries worked on this genome project, while a subset of nine laboratories funded the sequencing of the 290 million DNA bases using new high-throughput technologies, allowing the work to proceed without major dedicated grant funding.

The nine laboratories that funded the sequencing work of the Heliconius Genome Consortium include:

• University College London, UK, and Harvard University, USA: James Mallet
• University of Exeter, UK: Richard ffrench-Constant
• Harvard University, USA: Marcus Kronforst
• Muséum National d'Histoire Naturelle, Paris, France: Mathieu Joron
• Boston University, USA: Sean Mullen
• University of California at Irvine, USA: Robert Reed, Adriana Briscoe
• University of Edinburgh, UK: Mark Blaxter
• Smithsonian Tropical Research Institute, Panama: W. Owen McMillan
• Cambridge University, UK: Chris Jiggins

The study heralds a new era in genome biology, in which genome sequencing has become available to small groups of researchers for their own organism of choice.