Peppered moth

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Peppered moth (Biston betularia) is a species of temperate moth in the family Geometridae. It is well known for its role in the study of evolution, particularly regarding the phenomenon of industrial melanism. The peppered moth has been a key species in understanding how environmental factors can influence natural selection and genetic variation within a population.

Description

The peppered moth exhibits significant variation in wing coloration, ranging from light grey or white with small black specks, giving it a "peppered" appearance, to almost completely black. This variation is primarily due to a genetic mutation that affects the moth's coloration, leading to two main morphs: the typica (light) and the carbonaria (dark). The intermediate form, insularia, exhibits a phenotype between the two extremes.

Habitat and Distribution

Biston betularia is found across the Palearctic region, including parts of North America, Europe, and Asia. It inhabits a variety of habitats but is most commonly associated with wooded areas. The moth's distribution and population density can be influenced by environmental conditions and the presence of pollution.

Life Cycle

The peppered moth undergoes complete metamorphosis, with four distinct life stages: egg, larva (caterpillar), pupa, and adult. Females lay eggs on the underside of leaves, which hatch into caterpillars. These caterpillars feed on a variety of deciduous trees and shrubs, including birch, willow, and oak. After several weeks, the caterpillar pupates, emerging as an adult moth after approximately two weeks.

Industrial Melanism

The phenomenon of industrial melanism in the peppered moth is one of the most famous examples of natural selection in action. Prior to the Industrial Revolution, the typica morph was predominant due to its camouflage against lichen-covered trees, protecting it from predators like birds. However, as industrialization increased and soot blackened the trees, the darker carbonaria morph gained a selective advantage, becoming more common in polluted areas. This shift in population dynamics was first observed in the 19th century and has since been extensively studied as a classic example of evolutionary adaptation.

Research and Studies

The study of the peppered moth has contributed significantly to the field of evolutionary biology. Research by scientists such as Bernard Kettlewell in the 1950s, who conducted experiments on the natural selection process of the peppered moth, has provided empirical support for Darwin's theory of natural selection. Despite some controversy and debate over the methodology and interpretations of these studies, the peppered moth remains a key example of how environmental changes can drive evolutionary processes.

Conservation

While the peppered moth is not currently considered endangered, its story highlights the impact of human activity on the natural world. Conservation efforts aimed at reducing pollution and preserving natural habitats are essential for maintaining the biodiversity and ecological balance of areas where the peppered moth and other species live.