Question

Choose the correct statement regarding Darwin's theory of evolution.

• A. Branching descent and natural selection are two auxiliary concepts of this theory
• B. Natural selection is based on certain observations which are factual
• C. The theory was influenced by the work of Alfred Wallace on populations
• D. Both a and c

Answer 1

The correct option is B Natural selection is based on certain observations which are factual

Charles Robert Darwin was an English naturalist who proposed the theory of natural selection. According to Darwin, the individuals with favourable variations (the new characters allow them to face their surroundings) have a better chance of survival and they reproduce and establish. They are the fittest for survival and selected by nature. This process of selection is referred to as natural selection.

Natural selection is based on certain observations or features which are factual:

• Natural resources are limited: Due to over population, there is scarcity in the basic resources like food and shelter in any population.
• Members of a population vary in characteristics: No two individuals are alike except identical twins even though they look superficially similar.
• Most variations are inherited: The ancestral Darwin’s finches was a seed eating bird. Due to scarcity of food, they changed their food habits. Accordingly, the offsprings in successive generations developed a modified beak suitable for the food pattern.

Branching descent is the process of development of new species from a single common descendant like how branches of a tree originate from a common trunk. Different species descending from the common ancestor get adapted in different habitats. Example: Darwin's finches (varieties of finches arose from seed eaters) and Australian marsupials (evolved from common marsupials).

Hence, branching descent and natural selection are the two key concepts of Darwinian theory of evolution, not auxiliary concepts.

Darwin was influenced by the work of Thomas Malthus on populations, not of Alfred Wallace. In his essay, Thomas Mathus proposed that the food resources increase in arithmetic ratio but the population increases in geometric ratio. This leads to a competition among the individuals for the basic needs. This point gave the idea to Darwin that there is a struggle for existence among plants and animals and it can lead to variations in characteristics. Finally, the organism with better characters suitable for that particular environment will be selected by nature.

Alfred Wallace worked in Malay Archipelago (a group of islands between mainland Indochina and Australia) and came to similar conclusions as that of Darwin. He also believed that natural selection is a driving force for evolution.