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AP®︎/College Biology
Course: AP®︎/College Biology > Unit 7
Lesson 5: Evidence for evolutionBiogeography: where life lives
Biogeography explores the distribution of plants, animals, and organisms across Earth. New islands form habitats for unique species, like Galápagos finches and Hawaiian honeycreepers. Continental drift explains related species on different continents, with Pangaea's breakup separating organisms. Phylogenetic trees help trace species' movements, revealing Earth's dynamic biodiversity. Created by NOVA.
Want to join the conversation?
- So was there any certain event that caused pangea to separate into different continents?(4 votes)
- Pangea is just one in a long list of supercontinents going back to when plate tectonics first started somewhere around 3-3.5 billion years ago. It was made of many tectonic plates, and when those began to drift apart due to the convection currents in the mantle, Pangea split.(9 votes)
- I don’t understand biogeography very well.(2 votes)
Video transcript
Next up—biogeography. Well, biogeography is the study of how animals,
plants and other organisms have come to occupy the places on the globe that they do. Imagine a new island being born in the middle
of the ocean. At first, it’s a hunk of rock. Lifeless. But gradually, seeds and insects and small
animals, originating from nearby landmasses, get blown over on the winds. They come crashing ashore, pushed by the waves. Not all the organisms make it, but those that
do, with time, adapt to island living, perhaps even evolving into new species. Just take birds. There are the finches of the Galápagos Islands,
the birds of paradise of Papua New Guinea, the honeycreepers of Hawaii, and so on. In each case, a single island species diversified
into an array of species found nowhere else on Earth. Biogeography’s also got something to say
about why some closely related species flourish on different continents. It seems odd. Until you recall that Earth didn’t always
look this way. A few hundred million years ago, all land
was part of Pangaea—a hulking supercontinent. There were no vast oceans to interfere with
the movements of organisms. But then, starting about 170 million years
ago, the continents drifted like vast rafts across the sea. And the species living along the edges—they
were split in two. Fast-forward to the present day, and you get
a plant in South America whose close relatives grow in the tropical Pacific. We can use phylogenetic trees as sort of maps
to help us reconstruct the movements of organisms across the planet.