The breeding test

About this video

A tiny poodle and a huge shepherd dog look very different. A horse and a donkey look quite alike. Yet the two dogs belong to one species, and the horse and the donkey to two. Looks can fool you.

A species is one kind of living thing. The usual test in biology is breeding: a species is a group of living things that can breed together and have young that can themselves grow up and have young. All dogs pass. A poodle and a shepherd dog can have puppies, and those puppies can have puppies of their own. A horse and a donkey can have a baby together, a mule. Mules are strong, healthy animals, but they almost never have young of their own, so horses and donkeys are two separate species.

Every species has a scientific name in two words, a system Carl Linnaeus made popular in the 1750s. The first word names the genus, a small group of close relatives; the two together name the species. People are Homo sapiens, wise human. The leopard is Panthera pardus and its close relative the lion is Panthera leo. The same name is used in every language: palang in Persian, Leopard in German, but Panthera pardus for scientists everywhere.

How many species are there? Nobody knows. A study in 2011 estimated about 8.7 million species of animals, plants, fungi and other living things whose cells have a nucleus, and guessed that about 86 percent have not yet been found and named. Other scientists have made very different estimates. This video goes with the lesson What Is a Species? in Biology Level 1 on Knaph.

Transcript

1. 0:00A tiny poodle and a big shepherd dog look very different. A horse and a donkey look quite alike.
2. 0:09The usual test is breeding. A species can breed together, and its young can grow up and breed too.
3. 0:17A poodle and a shepherd can have puppies, and those puppies can have puppies. All dogs are one species.
4. 0:26A horse and a donkey can have a baby together, a mule. Mules are strong and healthy,
5. 0:33but they almost never have young of their own. So horses and donkeys are two separate species.
6. 0:42Every species has a two-word scientific name. People are Homo sapiens. Wise human.
7. 0:48The leopard is Panthera pardus. Its close relative, the lion, is Panthera leo.
8. 0:54In Persian it is palang, in German Leopard. Scientists everywhere write Panthera pardus.
9. 1:01How many species are there? A 2011 study estimated about 8.7 million whose cells have a nucleus.
10. 1:07It guessed that about 86 percent are not yet named. Other estimates differ a lot.
11. 1:15A species is a group that can breed together, and whose young can breed too.