Define adaptive radiation and give an example.

Define adaptive radiation and give an example.

• A. The merging of two species into one through hybridization
• B. A rapid diversification of a lineage into many species adapting to different niches; example: Darwin's finches
• C. A slow, uniform change across a population without forming new species
• D. Speciation driven by random genetic drift in small populations

Answer: (B)

Adaptive radiation is when a single ancestral lineage rapidly splits into many new species, each adapting to a different ecological niche after a new opportunity or habitat becomes available. A classic example is Darwin’s finches in the Galápagos, where an ancestral finch species diversified into multiple species with diverse beak shapes and sizes tailored to different foods—seeds, insects, nectar, and cactus. The other scenarios don’t capture this rapid, niche-filling diversification. Merging two species through hybridization reduces distinct lineages rather than creating many new ones. A slow, uniform change across a population describes gradual microevolution without forming new species. Speciation driven by random genetic drift in small populations can lead to new species, but it doesn’t inherently involve rapid diversification into multiple ecological roles like adaptive radiation.

Adaptive radiation is when a single ancestral lineage rapidly splits into many new species, each adapting to a different ecological niche after a new opportunity or habitat becomes available. A classic example is Darwin’s finches in the Galápagos, where an ancestral finch species diversified into multiple species with diverse beak shapes and sizes tailored to different foods—seeds, insects, nectar, and cactus.

The other scenarios don’t capture this rapid, niche-filling diversification. Merging two species through hybridization reduces distinct lineages rather than creating many new ones. A slow, uniform change across a population describes gradual microevolution without forming new species. Speciation driven by random genetic drift in small populations can lead to new species, but it doesn’t inherently involve rapid diversification into multiple ecological roles like adaptive radiation.