Simulado Intensivo TOEFL iBT - Reading Section

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The phenomenon of industrial melanism in the peppered moth (Biston betularia) stands as one of the most cited examples of natural selection in action. Prior to the Industrial Revolution in England, the light-colored, speckled form of the moth (typica) was predominant. This coloration provided effective camouflage against lichen-covered tree trunks, where the moths rested during the day, protecting them from visual predators like birds. The rare dark form (carbonaria) was at a distinct disadvantage, being more conspicuous against the pale background.

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The rapid environmental change brought about by industrialization, however, reversed this dynamic. Soot pollution from coal-burning factories killed the light-colored lichens and darkened the tree bark with particulate matter. In this newly darkened environment, the light-colored typica moths became highly visible to predators, while the formerly rare carbonaria form gained a survival advantage. Observations in the mid-19th century noted a dramatic increase in the frequency of the dark morph, particularly in heavily polluted areas near industrial centers like Manchester.

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The classic experiments by British ecologist Bernard Kettlewell in the 1950s provided compelling evidence for selective predation as the driving force behind this shift. Kettlewell released marked populations of light and dark moths in both polluted and unpolluted woodlands. Subsequent recapture rates demonstrated that in clean forests, more light moths survived, while in polluted forests, more dark moths survived. Direct observation confirmed that birds were indeed preying on the more visible moths. This was hailed as a clear, real-time demonstration of Darwinian natural selection.

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However, the simplicity of this narrative has been challenged in recent decades. Critics point out that peppered moths do not typically rest on tree trunks in the wild; early experiments may have used unrealistic moth placement. Furthermore, the role of other selective pressures, such as pollution toxicity affecting larvae differently or migration patterns, is not fully understood. While the correlation between soot pollution and melanism is undeniable, and selective predation is likely a major factor, modern evolutionary biologists now view the story as more complex than the textbook classic, emphasizing the multifaceted nature of evolutionary change.

The word "predominant" in paragraph 1 is closest in meaning to

According to paragraph 1, why was the light-colored typica moth successful before industrialization?

The phrase "this dynamic" in paragraph 2 refers to

Which of the following can be inferred from paragraph 2 about the carbonaria form during early industrialization?

The word "compelling" in paragraph 3 is closest in meaning to