Modelling evolution in the
peppered moth
2023-1-19
Biology pre-IB
INTRODUCTION
The Industrial Revolution, as it is known now, was taking place in England at that time.
Construction workers were constructing factories, which operated on coal. As a result, the
surrounding landscape was enveloped in a thick smoke. Previously bright and lichen-covered
trees were now dark and barren. The moths were obviously affected in some way by this.
Researchers started to look for an explanation. Charles Darwin proposed the theory of natural
selection to explain how new species evolve. Small variations exist among members of every
species in all forms of living organisms. If one of those variations enables the person to live
longer, they will probably produce more offspring. As that feature spreads, the population
becomes to resemble the successful. The species changes throughout time. J. W. Tutt proposed
that peppered moths were an illustration of natural selection in 1896. He realized that in the
pitch-black forest, the light moth's camouflage was ineffective. In a dark forest, dark moths can
survive longer and have more time to reproduce. Natural selection produces responses in all
living things. In contaminated forests, it was discovered that over 100 additional species of moth
gradually became darker. This impact is known scientifically as industrial melanism. The
peppered moth is still the product of natural selection. The majority of industrialized nations
have greatly reduced their pollution during the past 50 years. Dark moth populations are
declining as woods get cleaner, as anticipated by the theory.
My hypothesis was that white moths would struggle most against a white background, whereas
the darker peppered moths would have an advantage. This was proven to be true following the
experiment.
Process
1. Select a background (black, gray and white)
2. Place 10 of each moth on the background.
3. Select a person to take the role of a bird.
4. Ask him to turn around and pick the first moth he sees.
5. After each turn, pair the moths and add an additional moth for each pair, if the moth number is
uneven then remove one.
6. Repeat the process until one moth goes extinct and then change the background.
1
Result
In truth, the moths who stood out the most against the background died off first, and those that
blended in with the surroundings the best thrived. This experiment demonstrates how, even on an
insect scale, humans have an impact on the environment. With actual birds, it is more difficult. P.
A. Riley postulated a second selection factor in which melanin's role in heavy metal chelation
would shield peppered moths from the poisonous effects of heavy metals brought on by
industrialization. The primary selective process of unequal avian predation would be
supplemented by this selective advantage.
Final conclusion
Natural selection is influenced by small factors hardly visible to our eyes, in nature there are
many examples of this such as the Yangtze river dolphins that released on soundwaves for
navigation and went extinct quickly after loud factories were built in the rivers vicinity distorting
the dolphins' sense of navigation. Another example is the Blue footed booby, a bird that is
almost extinct today due to the introduction of rattus rattus (common rat) into their habitat, their
slow mating cycles which previously kept them alive now were the cause of their near extinction.
References
1. Book = "Last chance to see" by Douglas Adams
2. https://askabiologist.asu.edu/peppered-moths-game/natural-selection.html
3. https://askabiologist.asu.edu/peppered-moth
