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How does evolution help explain the distribution of plants and animals?

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World map using color coding to show the distribution of major floral kingdoms, subkingdoms, and regions. Key floral kingdoms include Boreal (green), Neotropical (pink), Paleotropical (yellow), South African or Capensic (purple), Australian (orange), and Antarctic (blue). Boundaries for subkingdoms, regions, and divisions are marked with different colored lines, and major regions such as Indoafrican, North American, and Malesian are labeled across continents. — biogeographic region Floral kingdoms, subkingdoms, and major regions of the world.

Evolution is fundamental to understanding the distribution of plants and animals, as it explains how organisms adapt to their environments and how their ranges shift over time. In the context of biogeography, evolution helps explain distribution patterns through several key mechanisms:12

Adaptation and Natural Selection: Organisms evolve specific traits to survive in particular habitats. Natural selection acts on these populations, favoring traits that allow survival in local climates or conditions, which often limits a species' range to areas where those adaptations are beneficial.345
Dispersal and Speciation: As populations spread from a center of origin, they may encounter geographic barriers. Over time, these isolated groups undergo speciation, evolving into distinct taxa. This explains why similar environments in different parts of the world may host different, yet ecologically similar, species.62
Vicariance: Large-scale geological events, such as continental drift, physically fragment the ranges of widespread species. Once separated by new barriers like oceans or mountain ranges, these populations evolve independently, leading to the unique flora and fauna observed in different biogeographic regions.6725
Historical Constraints: The age of a taxon and its evolutionary history influence its current distribution. Endemic species—those found only in specific areas—often reflect either ancient lineages that have retreated to small refuges (paleoendemics) or newly evolved species restricted by reproductive or geographic isolation (neoendemics).1248

By studying these patterns, scientists can infer past climatic changes, dispersal mechanisms, and the geologic history of Earth.92