Q.According to Darwin, the organic evolution is due to [AIPMT-2013] a) Intraspecific competition b) Interspecific competition c) Competition within closely related species d) Reduced feeding efficiency in one species due to the presence of interfering species

Industrial melanism (the peppered moth, Biston betularia, turning darker in polluted industrial areas) is a classic demonstration of natural selection favouring the phenotype best camouflaged against predators.

Before the Industrial Revolution in England, the light-coloured (speckled) form of the peppered moth was common because it was well camouflaged on lichen-covered, light-coloured tree bark, while the rare dark (melanic) form was easily spotted and eaten by birds. As industrial pollution blackened tree trunks (soot killed the lichens), the dark form became better camouflaged and the light form became conspicuous:

• Predatory birds selectively ate the light-coloured moths that stood out against the sooty bark.
• The dark-coloured moths survived and reproduced more, so their frequency in the population increased dramatically. …

The concept described — minute replicate particles from every body part — is the Theory of Pangenesis.

Pangenesis (proposed by Charles Darwin) held that every organ and tissue sheds tiny particles called gemmules ('pangenes'), which travel to the reproductive organs and are passed to offspring, supposedly transmitting the characters of each body part. It was later disproved but is historically important.

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