‘Jumping Gene’ Took Peppered Moths To The Dark Side
News Jun 03, 2016
The new findings solve a crucial missing piece of the puzzle in this iconic textbook example of evolution by natural selection.
The typical form of the peppered moth has light-coloured wings. However, during the industrial revolution the dark form displaced the lighter form by blending in with the sooty bark on urban trees and avoiding predation.
In a new paper published in Nature, scientists have discovered that a ‘jumping gene’ mutation was responsible for this dark variant. Using statistical modelling, this mutation has been independently dated to around 1819, which is consistent with the historical record.
Jumping genes, more formally known as transposable elements (TEs), are mobile segments of DNA that can change their position within a genome and alter the expression of other genes. Using fine-scale linkage and association mapping combined with next-generation DNA sequencing, the team established that a large transposable element, inserted within the moth’s cortex gene, was responsible for the colour change.
Dr Ilik Saccheri, from the University’s Institute of Integrative Biology, who led the research, said: “This discovery fills a fundamental gap in the peppered moth story. The fact that this famous mutant is caused by a transposable element will hopefully attract more interest in the impact of mobile DNA on fitness and the generation of novel phenotypes.”
Back in time
The first documented sighting of a black peppered moth is from Manchester in northern England, in 1848. However, it could have existed undetected in the moth population at very low frequency for many years earlier.
To independently estimate when the mutation happened, the team used a simulation-based statistical ‘time machine’ to infer the number of generations needed to arrive at the observed pattern of variation in the DNA sequence flanking the transposable element.
Dr Pascal Campagne, who worked on the study, said: “Our best estimate of 1819 shows that the mutation event occurred during the industrial revolution and that it took around 30 years for it to become common enough to be noticed.”
Co-author Dr Arjen van’t Hof added: “These findings provide an opportunity to further develop peppered moth industrial melanism as a tool for teaching evolutionary biology and the genetic basis of adaptation.”
A parallel paper in the same journal by researchers from the Universities of Cambridge and Sheffield reveals that the same cortex gene also enables tropical butterflies to mimic each other’s bright and colourful patterning.
Dr Saccheri commented: “This is highly unexpected, both because the butterfly and moth polymorphisms appear very different to the eye, and the species are separated by over 100 million years. What this suggests is that the cortex gene is central to generating pattern diversity across the Lepidoptera, and more generally that adaptive evolution often relies on a conserved toolkit of developmental switches.”
"Genetic Jenga" Helps Understand How Our Genes Control Our CellsNews
To fully understand how our cells work, we can't focus on just one gene, but must instead look at combinations of genes. Researchers have published a study which knocked out multiple genes, like removing bricks from a Jenga tower, to better understand how they work together.READ MORE
How Environmental Pollutants and Genetics Work Together in Rheumatoid ArthritisNews
It is well known that individuals with a particular version of human leukocyte antigen have an increased risk for rheumatoid arthritis, but there has been growing interest in the role of environmental pollutants. In a new mouse study, researchers probed the relationship between the two.READ MORE
Comments | 0 ADD COMMENT
International Conference on Epigenetics and Epitranscriptomics
Sep 17 - Sep 18, 2018