Evolution — NEET Biology Questions 2026

NCERT states Homo sapiens arose in Africa and spread globally.

In small populations, chance events can significantly affect allele frequencies.

The Neanderthals were present before Homo sapiens and are now extinct.

Both statements are true from NCERT. NCERT states “Due to the same continental drift pouched mammals of Australia survived because of lack of competition from any other mammal.” The Reason explains WHY Australian marsupials survived better - isolation prevented competition from placental mammals that displaced marsupials elsewhere.

This question requires arranging the events that lead to speciation via adaptive radiation in a logical and NCERT-consistent sequence. 1. **(b) Colonization of a new, isolated geographical area by an ancestral species:** Adaptive radiation often begins when a species reaches a new environment, like an island or an unexploited region. 2. **(c) Availability of multiple diverse, unoccupied ecological niches:** The new environment typically offers various resources and ways of life that are not yet utilized, providing opportunities for diversification. 3. **(d) Natural selection favoring individuals with traits better suited to specific niches:** Within the ancestral population, individuals with variations that allow them to better exploit particular niches are naturally selected and survive to reproduce more. 4. **(e) Diversification of feeding habits and structural adaptations in different subpopulations:** Over generations, different groups of the ancestral population adapt to different niches, leading to distinct traits and behaviors (e.g., changes in beak shapes for different food types in finches). 5. **(a) Accumulation of distinct genetic changes and reproductive isolation among subpopulations:** Continued adaptation and divergence in different niches lead to genetic differences. Eventually, these subpopulations become reproductively isolated, meaning they can no longer interbreed. 6. **(f) Establishment of multiple new species adapted to distinct habitats within the area:** Once reproductive isolation is complete, distinct new species are formed, each specialized for its particular habitat/niche within the radiated area. Therefore, the correct sequence is (b) → (c) → (d) → (e) → (a) → (f). The tested concept is the sequential understanding of the process of adaptive radiation, integrating concepts of colonization, niche availability, natural selection, adaptation, genetic change, and speciation.