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How does the geographic distribution of plants and animals help reveal evolutionary history?
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phylogeny
Tentative phylogenetic scheme for the evolution of the human lineage. Solid bars indicate the time ranges during which species are thought to have existed, based on fossil evidence. Dotted lines signify evolutionary relationships between hominin species that have been proposed on the basis of the fossil evidence.
The geographic distribution of plants and animals, studied through biogeography, provides critical evidence for evolution by revealing how historical and environmental factors have shaped the diversity of life.
Geographic patterns help reconstruct evolutionary history in several ways:
- Continental Drift and Vicariance: The fragmentation of landmasses through continental drift explains why similar species are found on widely separated continents. When a population is split by a new physical barrier, such as a rising sea or mountain range, the isolated groups evolve independently—a process known as vicariance.
- Adaptive Radiation: When organisms colonize remote areas like islands, they often encounter unoccupied ecological niches. This allows them to diverge rapidly from a common ancestor into multiple new species, a process called adaptive radiation. Examples include the Galapagos finches and Hawaiian honeycreepers.1
- Dispersal: Patterns of distribution also reflect the ability of species to cross barriers. Species found on islands separated by shallow water suggest a past connection to the mainland, whereas dissimilar faunas across deep seaways indicate long-standing barriers to migration.23
By analyzing these distributions alongside fossil records, scientists can map the movement and diversification of lineages over geologic time.43