Literature Analysis: Peppered Moth Evolution and Industrial Melanism

This report provides a comprehensive literature analysis of the evolution of the peppered moth (Biston betularia), focusing on the phenomenon of industrial melanism. The analysis delves into the genetic mechanisms underlying the moth's adaptation to environmental changes, particularly the impact of coal pollution during the Industrial Revolution. The report examines the role of the cortex gene and the insertion of a transposable element in the development of the dark-colored carbonaria form. It compares the peppered moth's adaptation to that of the rock pocket mouse, highlighting the role of natural selection. Furthermore, the report discusses the findings of relevant research papers, including those by van't Hof et al. (2016) and others, and addresses alternative hypotheses regarding the mutation process. The analysis also considers the timing of the carbonaria mutation and its relationship to the historical record. The report concludes with a review of recent studies and provides a detailed understanding of the evolutionary processes involved.

Running head: PEPPERED MOTH EVOLUTION: LITERATURE ANALYSIS
PEPPERED MOTH EVOLUTION: LITERATURE ANALYSIS
Name of the Student
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Author’s Note

1PEPPERED MOTH EVOLUTION: LITERATURE ANALYSIS
Table of Contents
Answer 1....................................................................................................................................2
Answer 2....................................................................................................................................2
Answer 3....................................................................................................................................3
Answer 4....................................................................................................................................3
Answer 5....................................................................................................................................4
Answer 6....................................................................................................................................5

2PEPPERED MOTH EVOLUTION: LITERATURE ANALYSIS
Answer 1
Prior to the Industrial Revolution of the 1800s, the Peppered Moth population (Biston
betularia) was mainly with light colored body and darkened spots which aided in
camouflaging adaptive strategy to avoid predators and dark coloured moths were rarely. The
few dark colored moths were effortlessly picked out by birds and other visual predators
because they were easily seen against the light background of the trees.
The carbonaria in B. betularia was found to be in the first intron of the cortex gene.
The insert which is labeled as carb-TE, is class II transposable element which has a 9-kb
(approximate) non-repetitive sequence which is two and a third times tandemly repeated. The
6 base pairs of the inverted repeats along with 4 base pairs duplicates found at the target site
that is not present in the light coloured moths. The stage of the rapid wing disc
morphogenesis shows a higher expression of the Carb-TE.
Answer 2
The data used to generate fine genetic mapping along with the ageing analysis was
taken from moth transect samples of 2002, along with 12 carbonaria and 6 insularia samples
collected in between 2005 to 2009 from North west England–North Wales.
The data for figure 1 is used to illustrate the genetic mutation of carbonaria where fig
1 a shows the 400-kb gene portion flanked by markers b and d indicating the positions of
genotyping of carbonaria moth. The observations of Figure 1 b highlight the polymorphism
regions along with intron and exon arrangement of the cortex gene in carbonaria. Figure 1c
shows the structure and location of the insert in the carbonaria cortex gene sequence,
corresponding to class II DNA transposon comprising of 9 kb tandem repeats of two and one-

3PEPPERED MOTH EVOLUTION: LITERATURE ANALYSIS
third times named repeat units RU1–RU3 along with 3 short tandem sub repeat units named
SRU1–SRU9 present within each RU.
1. How the expression of the gene was increased?
2. Is only one gene (Cortex gene) only gene involved?
3. Why is intron splicing not considered behind the mutation?
4. Instead of transposable elements and jumping genes, why is random mutation
followed by natural selection not being considered?
Answer 3
Instead of transposable elements and jumping genes, why is random mutation followed by
natural selection not being considered?
The alternative hypothesis can be that due to random mutation of the cortex gene, the
melanism of the moths took place which was naturally selected in the backdrop of industrial
revolution of the 1800s due to predation and darkening of the tree barks due to pollution.
Organized genetic rearrangement with transposable elements and jumping genes might not
have been behind the mutation. Random mutation promoting melanism of the moths is a
good alternative hypothesis.
Answer 4
The observation of Figure 2 elucidates the pattern of recombination along with ageing
analysis of the carbonaria transposable element mutation where (a) highlights the
recombination that is nearest between the haplotypes of carbonaria and the haplotypes of non
carbonaria including typica and insularia. The observation of 2b figure is illustration of
multi locus linkage disequilibrium of the haplotypes of carbonaria and the haplotypes of non

4PEPPERED MOTH EVOLUTION: LITERATURE ANALYSIS
carbonaria including typica and insularia whereas figure 2c observes the introgression of the
carbonaria haplotype into non carbonaria haplotypes. The analysis of figure 2 d reveals the
ageing of the carbonaria transposable elements where maximum density is seen in the year
1819, highly coinciding with the impact of industrial revolution and increase of carbonaria
and fall of the non carbonaria (typica and insularia).
The main conclusion is that the rise of the carbonaria occurred after the industrial
revolution of the 1800s.
There were uncertainties regarding the time gap between the appearance of the
mutation and the first sighting of dark coloured moths.
The time gap between the appearance of the mutation at 1819 (highly skewed data
with median of1763 and an interquartile range between 1681–1806), as indicated in Figure
2d, and the first sighting of dark coloured moths at 1848 might be due to erosion of the
ancestral carbonaria haplotype due to genetic recombination and mutation.
Answer 5
Both the Peppered Moth and Pocket Mouse’s (Chaeotdipus intermedius) adaptation
from light to dark is based on environmental impact causing them to seek better adaptive
techniques to camouflage themselves from predators and blend in with the surroundings of
their natural habitat.
The phenotypic intraspecific divergence due to extensive color variation seen within the
various species of the rock pocket mouse followed by migration and natural selection is the
reason behind the increase of population of the dark coloured rock pocket mouse. As no
correlation was noted between the color variations and mitochondrial DNA phylogeny

5PEPPERED MOTH EVOLUTION: LITERATURE ANALYSIS
amongst the varying colored species of the pocket mouse, suggested that the pelage
coloration had evolved rapidly.
However the mutation of the peppered moth is by caused by the transposable element
leading to increased melanism. The insert which is labeled as carb-TE, is class II transposable
element which has a 9-kb (approximate) non-repetitive sequence which is two and a third
times tandemly repeated. The 6 base pairs of the inverted repeats along with 4 base pairs
duplicates found at the target site that is not present in the light coloured moths. The stage of
the rapid wing disc morphogenesis shows a higher expression of the Carb-TE.
Answer 6
No, not much has been discovered after the research work by van’t Hof et al. (2016). Wing
architecture and colour patterns in Heliconius erato has been studied by Van Belleghem et al.
(2017) but no new information on peppered moth evolution has been asserted yet.
Review:
Chuong, E. B., Elde, N. C., & Feschotte, C. (2017). Regulatory activities of transposable
elements: from conflicts to benefits. Nature Reviews Genetics, 18(2), 71.
Primary article:
Van Belleghem, S. M., Rastas, P., Papanicolaou, A., Martin, S. H., Arias, C. F., Supple, M.
A., & Ruiz, M. (2017). Complex modular architecture around a simple toolkit of wing pattern
genes. Nature ecology & evolution, 1(3), 0052.