What is a species?

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0:00The most famous definition of a “species” was proposed by the biologist Ernst Mayr

0:04back in the mid-1900s: species are groups of interbreeding natural populations that

0:08for one reason or another, don’t have babies with each other. But it turns out to be super

0:13hard to determine whether groups are actually reproductively isolated, so other folks have

0:16tried to define what a species is based on looks, or genetic similarity, or evolutionary history,

0:22or… well, it keeps going. These days, scientists across different fields regularly use more than a

0:27dozen different so-called “species concepts”. See, there’s a huge scientific debate about

0:32whether the red wolf is just a hybrid between a coyote and a gray wolf, or whether it’s

0:36actually its own separately-evolving species, OR maybe it used to be its

0:39own thing but that thing went extinct and the current thing is actually a new hybrid?

0:43And that doesn’t even get into how weird plants are about this stuff. Like,

0:46some plants can literally double their genome when they reproduce – creating a totally new

0:51species in a single generation – which wreaks all sorts of havoc on any attempts to clearly

0:55differentiate between species. So it is really difficult to define a species.

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