Breed vs species: what's the difference between these two terms?

A species is the name of a group of individuals that can mate to produce fertile offspring. If individuals cannot mate or can mate but cannot produce fertile sons and daughters, then they are not the same species.

For example, while lions and tigers can mate to produce offspring (‘ligers’ or ‘tigons’), their sons are always sterile and therefore lions and tigers are classified as different species.

• Wild hybrids: Unlike the liger, these 3 real-life crossbred animals naturally exist in the wild
• Do animals cross breed with other species in the wild? How and why interbreeding between different species happens

Different species often form due to geographic barriers such as mountain ranges or rivers, which separate populations of the same species until they have become so different that they can no longer mate to produce fertile offspring.

Breeds, on the other hand, are different ‘types’ of domesticated animals that humans have created through artificial selection.

For example, great danes and chihuahuas are two breeds of domesticated dog. But these two breeds can still interbreed to produce fertile offspring and are therefore considered the same species.

Though domestic dogs were reclassified as a grey wolf subspecies in the early 1990s, they’re still capable of producing fertile offspring with their wild counterparts.

• Wolf vs dog: what's the difference between man's best friend and its wild cousin?

So, despite different Latin names, the domestic dog (Canis lupus familiaris) and grey wolf (Canis lupus) can technically be considered the same species. 

• When did dogs split from wolves and become their own distinct species?
• Is there a wild wolf in your sitting room? How your pet dog might have more in common with its wolf ancestors than you might think...