29. After implication of Green Air Act in England whichinsect form become virtually absent-
    (1) Biston betularia carbonifera
    (2) Biston betularia typical
    (3) Drosophila
    (4) Apes Americana

Introduction

The story of the peppered moth in England is one of the most famous examples of natural selection in action. The dramatic shift in moth populations during and after the Industrial Revolution illustrates how environmental changes can directly influence the survival of different forms within a species. The implementation of the Green Air Act marked a turning point, reversing earlier trends and leading to the near disappearance of the dark, melanic form of the peppered moth.

The Rise of the Dark Moth: Industrial Melanism

During the 19th and early 20th centuries, industrial pollution in England caused tree trunks to darken with soot, killing the pale lichens that once covered them. The dark (carbonaria) form of the peppered moth thrived in these conditions, as it was well camouflaged against the polluted trees, while the lighter (typica) moths were easily spotted and eaten by birds.

Clean Air Legislation and Its Impact

With the introduction of the Green Air Act and similar clean air policies, pollution levels dropped, and the environment began to recover. Lichens returned, and tree bark lightened. This shift reversed the camouflage advantage: the dark carbonaria moths now stood out, while the light typica moths blended in once more.

The Decline of Biston betularia carbonifera

As a direct result of these environmental improvements, the population of the dark carbonaria form plummeted. In many areas, it became virtually absent, and the light typica form once again dominated the landscape. This change is a textbook example of how human intervention and environmental policy can influence natural selection and species adaptation.

Conclusion

The decline of Biston betularia carbonifera after the Green Air Act in England is a powerful demonstration of evolution in real time. It highlights the dynamic relationship between organisms and their environment, and the profound impact that human actions can have on the natural world.

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