Butterflies, moths share ancient ‘blocks’ of DNA, reveals study

Butterflies and moths share 'blocks' of DNA that are more than 200 million years old, reveals new research.

A team of scientists from the Universities of Exeter (UK), Lübeck (Germany) and Iwate (Japan) developed a tool in order to compare the chromosomes (DNA molecules) of several butterflies and moths.

They then discovered that the blocks of chromosomes, that exist in all the species of moths and butterflies and also in Trichoptera, which are aquatic caddisflies that share a common ancestor with moths and butterflies dating back nearly 230 years ago.

Moths and butterflies, collectively known as Lepidoptera, have widely varying numbers of chromosomes, from 30 to 300, but the research's findings show exceptional proof of shared blocks of homology (similar structure) going back through time.

“DNA is compacted into individual particles or chromosomes that form the basic units of inheritance,” Professor Richard ffrench-Constant, from the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall said.

“If genes are on the same ‘string’, or chromosome, they tend to be inherited together and are therefore ‘linked’".

“However, different animals and plants have widely different numbers of chromosomes, so we cannot easily tell which chromosomes are related to which."

“This becomes a major problem when chromosome numbers vary widely – as they do in the Lepidoptera."

“We developed a simple technique that looks at the similarity of blocks of genes on each chromosome and thus gives us a true picture of how they change as different species evolve."

“We found 30 basic units of ‘synteny’ (literally meaning ‘on the same string’ where the string is DNA) that exist in all butterflies and moths, and go back all the way to their sister group the caddisflies or Trichoptera.”

Butterflies, which are often noticed as the key indicators of conservation, have witnessed a decline in their species worldwide due to human activity.

This study shows how butterflies can be useful models for the study of chromosome evolution.

The research also enhances the scientific understanding of how moth and butterfly genes have evolved over time. Also, similar techniques can be deployed to gain insights into the evolution of chromosomes in other groups of animals or plants.