Which concept describes a rapid increase in the number of species with a common ancestor, characterized by great ecological and morphological diversity?

• A. Gradualism
• B. Punctuated Equilibrium
• C. Adaptive Radiation
• D. Allopatric Speciation

Answer: (C)

Adaptive radiation is the rapid diversification of a single ancestral lineage into many species that occupy a variety of ecological roles and show a range of morphologies. This happens when a lineage colonizes new environments with many unfilled niches or after a disruption frees up ecological space, allowing descendants to adapt to different resources and conditions. The result is a burst of speciation from one ancestor and a broad array of forms and lifestyles. Classic examples include Darwin’s finches in the Galápagos, cichlid fishes in African lakes, and the Hawaiian honeycreepers.

Other ideas describe different aspects of evolution: gradualism emphasizes slow, steady changes over long periods; punctuated equilibrium focuses on bursts of change separated by long periods of little change, not necessarily driving diversification across niches; allopatric speciation involves geographic separation creating new species, which can contribute to adaptive radiations but isn’t the description of the rapid, niche-diversifying pattern itself.