Fresh Study Unveils Ancient DNA “Blocks” Shared by Butterflies and Moths

Recent research has unveiled a fascinating discovery regarding butterflies and moths, revealing that they share distinct segments of DNA with a lineage dating back over 200 million years. A collaborative effort by scientists from the Universities of Exeter (UK), Lübeck (Germany), and Iwate (Japan) led to the development of an innovative method for analyzing the chromosomes of various butterfly and moth species.

Through their research, they identified these DNA segments, or “blocks of chromosomes,” which are present in all species of moths and butterflies. Astonishingly, these genetic blocks also exist in Trichoptera, the aquatic caddisflies, which shared a common ancestor with moths and butterflies approximately 230 million years ago.

While moths and butterflies, collectively known as Lepidoptera, exhibit a wide range of chromosome numbers, spanning from 30 to 300, this study offers compelling evidence of shared genetic homology, tracing back through the annals of evolutionary history. Professor Richard ffrench-Constant, affiliated with the Centre for Ecology and Conservation at Exeter’s Penryn Campus in Cornwall, explains the significance of this finding, emphasizing the role of DNA in inheritance:

“DNA is compacted into individual particles or chromosomes that form the basic units of inheritance. 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.”

To address this challenge, the researchers developed a straightforward technique that examines the similarity of gene blocks on each chromosome, providing insight into how these blocks evolve as different species diverge. Their investigation identified 30 fundamental units of ‘synteny,’ a term denoting shared genetic structure, present in all butterflies and moths, tracing their ancestry back to the caddisflies or Trichoptera.

While butterflies are commonly recognized as vital indicators of conservation, this study underscores their significance as models for studying chromosome evolution. Furthermore, it enhances our scientific comprehension of the evolutionary history of moth and butterfly genes. Importantly, the methods employed in this research may also yield valuable insights into the evolution of chromosomes in other animal and plant groups.

[Reference: “Lepidopteran Synteny Units reveal deep chromosomal conservation in butterflies and moths” by Walther Traut, Ken Sahara, and Richard H ffrench-Constant, published on June 13, 2023, in G3: Genes, Genomes, Genetics, DOI: 10.1093/g3journal/jkad134.]

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