What is the Great American Interchange?
Q: What is the Great American Interchange?
A: The Great American Interchange was an important zoogeographic event that occurred about three million years ago, when land and freshwater fauna migrated between North America and South America.
Q: When did this migration happen?
A: The migration happened during the Pliocene, 3.6–2.6 million years ago (mya).
Q: How did it occur?
A: It occurred when the volcanic Isthmus of Panama rose from the seafloor and bridged the two continents, joining the Neotropic (roughly South America) and Nearctic (roughly North America) ecozones to form the Americas.
Q: What were some of its effects?
A: Its most dramatic effect was on the distribution of mammals, but weak-flying or flightless birds, reptiles, amphibians, arthropods and even freshwater fish also migrated.
Q: Who first discussed this concept?
A: The concept was first fully laid out in 1876 by Alfred Russel Wallace who had spent 1848–1852 exploring and collecting specimens in the Amazon Basin.
Q: Were there similar interchanges earlier in history?
A: Yes, similar interchanges occurred earlier in history when India and Africa made contact with Eurasia about 50 mya and 30 mya respectively.
