New research reveals that butterflies, moths and water bugs share ‘blocks’ of DNA dating back more than 200 million years, identified using a tool developed by scientists from universities in the UK, Germany and Japan. This discovery, which illustrates the association and evolution of chromosomes between these species, not only sheds light on their genetic history, but also potentially aids in the study of chromosome evolution in other organisms.
New research shows that butterflies and moths share ‘blocks’. DNA more than 200 million years old.
Researchers from the universities of Exeter (UK), Lübeck (Germany) and Iwate (Japan) have developed a method to analyze the chromosomes of various butterflies and moths.
Chromosomes of the African monarch butterfly. Red dots highlight the ends of each chromosome using a DNA probe coupled to a fluorescent reporter. Credit: University of Exeter
They found blocks of chromosomes that exist in all moths and butterflies speciesand also in Trichoptera – aquatic crustaceans that shared a common ancestor with moths and butterflies about 230 million years ago.
Moths and butterflies (collectively called Lepidoptera) have very different numbers of chromosomes – from 30 to 300 – but the study results show remarkable evidence of shared blocks of homology (similar structures) going back in time.
“DNA is compacted into individual particles, or chromosomes, which form the basic units of heredity,” said Professor Richard ffrench-Constant from the Center for Ecology and Conservation at Exeter’s Penryn Campus in Cornwall.
“If genes are on the same ‘strand’ or chromosome, they tend to be inherited together and are therefore ‘linked’.
“However, different animals and plants have very 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 Lepidoptera.”
Male and female African monarch mating. Credit: University of Exeter
“We’ve developed a simple technique that looks at the similarity of blocks of genes on each chromosome, giving us a true picture of how they change as different species evolve.
“We found 30 basic units of ‘synteny’ (literally meaning ‘on the same strand’, where the strand is DNA) that exist in all butterflies and moths, and go all the way back to their sister group of beetles or Trichoptera.”
Butterflies are often considered key conservation indicators, and many species are declining worldwide due to human activity.
However, this study shows that they are also useful models for studying chromosome evolution.
The study improves scientific understanding of how moth and butterfly genes evolved, and importantly, similar techniques may also provide insight into chromosome evolution in other groups of animals or plants.
Reference: “Lepidopteran Synteny Units Reveal Deep Chromosomal Conservation in Butterflies and Moths” by Walther Traut, Ken Sahara and Richard H ffrench-Constant, 13 Jun 2023, G3: Genes, genomes, genetics.
DOI: 10.1093/g3journal/jkad134
