If animal species are determined by animals not being able to have viable offspring, how are plant species determined?


Such as (made up example, idk if it’s real) you may be able to cross bread oranges and lemons, and get something you can plant and grow.

In: Biology

Exactly the same way – natural evolution. Where things get complicated is humans … *encouraging* evolution by selecting specific plants and selectively breeding them. Google for ‘Hybrid Citrus’, you`ll be surprised at what fruits humans have created.

Cross-breeding or selective breeding in this way only needs the species to be genetically close enough. You can`t cross an apple and a tomato, but a great example of where you can are dogs – they can all interbreed so it is possible to cross a bulldog with a shi-tzu and end up with a bullshit. Actually true, though they’re really called bull-tzu, which is far less fun.

Actually the answer isn’t that simple on the animal side either! For instance, there’s what’s called a ring species: imagine a large area that forms a ring, say, around a mountain. There are (made up example) rodents that live around this geographical ring, and the north ones can interbreed with the east ones, who can interbreed with the south ones, who can interbreed with the west ones, who can interbreed with the north ones, but the north ones can’t interbreed with the south ones. Where do you draw the species line?

Interbreeding is the basis for what’s known as the biological species concept, but there are other species concepts. And yeah, people tend to think the biological species concept doesn’t work so well for plants (though Ernst Mayr tried to prove it does).

One good alternative is what’s called the phylogenetic species concept. This defines a species as a group of organisms that share a unique common ancestor.