How does the geologic history of continents affect modern biogeographic regions?

The geologic history of continents is a primary driver of modern biogeographic regions, as the movement of landmasses dictates the isolation, dispersal, and evolution of flora and fauna.12

Mechanisms of Geologic Influence

The theory of plate tectonics explains how the shifting of continents has shaped biotic distributions through two main processes:

• Vicariance: As continents drift and fragment, populations are physically separated by new barriers (such as oceans), leading to independent evolution and the development of distinct regional biotas.34
• Dispersal: The formation of land bridges, such as the connection between North and South America during the Pliocene, allows for the intermingling of previously isolated species.15

Historical Context

During the Mesozoic Era, the supercontinent Pangaea allowed for relatively free movement of life. Its subsequent breakup into Laurasia and Gondwanaland fundamentally altered these patterns. For example, Australia has remained isolated since the Eocene Epoch, resulting in its highly unique flora and fauna. Similarly, the Wallace Line serves as a famous, albeit debated, boundary reflecting the deep-seated faunal differences between Asian and Australian regions caused by tectonic history.167