Summary
Peppered moths can be found in the British Isles, Ireland, mainland Europe, and North America. Their natural habitats are forests, countryside, and back gardens.
Moth larvae look like small twigs, allowing them to hide from predators. They can also change their pigment to blend in with leaves and trees.
Winter is the pupal stage for peppered moths, so they spend the cold season in cocoons.
Light-colored, light gray, or white.
Dark-colored, black, or melanic.
Natural Selection
The Industrial Revolution was a paradigm shift in production. Production of items and goods by hand has been replaced by mass manufacturing in factories.
The color change was a natural genetic mutation.
It is Charles Darwin’s biological concept; those individuals with qualities that provide quick adaptation to external changes have more offspring and, as a result, drive the change in the whole population to successful survival.
Coal air pollution in England in the 19th century made the environment for dark-colored peppered moths more favorable and degraded it for light-colored ones. It became easier for dark-colored moths to hide from predators, so their population increased significantly.
Dr. Kettlewell
An entomologist is a scientist in the discipline of entomology; these scholars study insects.
Scientists make a prediction based on the available theoretical knowledge. They then test it and compare the observed result with the forecast made.
Dr. Kettlewell observed, compared the results with the available data, and then ran two experiments that confirmed his hypothesis.
He released pre-marked groups of moths into pristine and polluted forests. More dark-colored individuals survived in a dark forest than light ones, and vice versa for the non-polluted forest.
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Final Analysis
The pigment of the moths hides or highlights them on a specific surface, which is the bark of trees. It is difficult for predators to find and catch dark moths hiding in the dark trunk.
Conversely, light ones are an easy target for birds in a polluted forest as their color contrasts with their environment. Dark moths have more room to move, eat, shelter, and breed in polluted forests and therefore have a greater chance of survival.
The clear forest is a natural habitat for two populations of peppered moths, with a significant difference in wing color between them. Light-colored moths have the advantage of being less visible to predators. It allows them to live longer and have more offspring. Eventually, the light-colored population becomes dominant as predators exterminate all the dark-colored ones. The best adapting population survives, and the appearance of all moths of this species in the light forest changes forever.
Interbreeding a light-colored population with a dark-colored one would be the most likely outcome. It would lead to the appearance of individuals with mixed pigmentation. The absence of predators means freedom of movement; two populations would no longer be limited to live and hiding on trees of a specific color. However, the lack of predators in the environment also leads to an overpopulation of prey species. As a result, food resources are depleted, and living space becomes less and less. It would result in multiple diseases in the peppered moths’ population and their extinction until the environment regains its resources.
Dark-colored moths would probably disappear from places near factories because their pigmentation would no longer match the environment.
Simply put, it would be easier for predators to hunt them. Their place is most likely to be taken by light-colored individuals.
We know that moths evolved by applying the scientific method to existing theoretical knowledge and newly acquired data. Comparison and analysis of predictions and results allow one to develop new knowledge.