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7.2. Species concept

Species concept

Two individuals belong to the same species if they can reproduce with each other in nature, and not because they are very similar.

The concept is clear when we talk about a frog, a fly, a pine tree and a trout, for example, we know that they are different species. But we can have the doubt that two dogs, a mastiff and a poodle are the same species because they are very different.

Individuals belong to the same species if they can reproduce with each other, and their offspring are fertile.

Therefore, as a mastiff and a poodle can have fertile offspring, we can say that they are of the same species.

On the other hand, if a donkey (ass) is crossed with a mare, they may have a hybrid known as a mule as offspring, but it will not be fertile, it will not be able to have offspring. Therefore, the donkey and the mare are not of the same species.

Hinnies are the result of a cross between a horse and a donkey (or female donkey), and would also not be fertile. 

Although we normally refer to a species by its common name, this can be misleading. For example, depending on where we live, we can call a common magpie, picaraza, pica, queer or paste. That speaking in Spanish, because in each language its denomination is different. To avoid these errors, the scientific name is used, it consists of two words:

  • The first word is the name of the genus, and its first letter is capitalized.
  • The second word corresponds to the species.

Thus, in the example that we have given, if we talk about Pica pica, we will have no doubt as to which living being we are referring to.