AP Biology 7.10.B: Rates and Patterns of Evolution

Practise AP Biology 7.10.B questions by comparing gradualism, punctuated equilibrium, divergent evolution, adaptive radiation and convergence.

Exam points

distinguish punctuated equilibrium from gradualism using the rate and timing of evolutionary change
explain how new habitats, isolation and adaptive radiation can produce divergent evolution and rapid speciation
identify convergent evolution from similar adaptations under similar selection pressures despite different ancestry

[Maximum number: 1]

Twenty million years ago the Caribbean Sea and Pacific Ocean were connected, and water

flowed freely between the two bodies of water. Many of the same marine species were found

in both areas. Over millions of years, the land referred to as the Isthmus of Panama formed,

eventually closing off the connection between the Caribbean Sea and Pacific Ocean and creating

two separate bodies of water. The ecology of these two marine habitats was dramatically altered

by this land formation. The warmer Caribbean water could no longer flow west, so the Pacific

water cooled and became more nutrient-rich, while the Caribbean water became warmer.

Explain how the isolation of marine species by the formation of a land barrier can lead to

divergent evolution of those species.

The formation of the Isthmus of Panama connected two continents, North America and South

America. Many North American land animal species migrated to South America after the

formation of the isthmus and occupied similar niches as South American species.

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