Download `Jumping gene` took peppered moths to the dark side

'Jumping gene' took peppered moths to the
dark side
1 June 2016
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.
A mating pair of melanic peppered moths. Credit: Dr Ilik
Saccheri
Researchers from the University of Liverpool have
identified and dated the genetic mutation that gave
rise to the black form of the peppered moth, which
spread rapidly during Britain's industrial revolution.
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 lightcoloured 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.
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."
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."
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.
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."
Jumping genes, more formally known as
A parallel paper in the same journal by researchers
1/2
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."
The study 'The Industrial melanism mutation in
British peppered moths is a transposable element'
was funded by the Natural Environment Research
Council (NERC) and is published in the June 2,
2016 issue of Nature.
More information: Nature, DOI:
10.1038/nature17951
Related paper: Nature, DOI: 10.1038/nature17961
Provided by University of Liverpool
APA citation: 'Jumping gene' took peppered moths to the dark side (2016, June 1) retrieved 15 June
2017 from https://phys.org/news/2016-06-gene-peppered-moths-dark-side.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
2/2
Powered by TCPDF (www.tcpdf.org)