Why can’t different species impregnate eachother? For instance, a German shepherd can breed with a pug, but can’t breed with a deer.

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Why can’t different species impregnate eachother? For instance, a German shepherd can breed with a pug, but can’t breed with a deer.

In: Biology

Amount of DNA is different. The genes on chromosomes are different.
Gametes of different species do not have the right proteins to recognize each other and fuse.
Mating behavior and mate selection between different species are too different to allow for breeding.

There’s ways that egg cells recognize viable sperm cells. They use proteins that link together in order to make a working connection.

Think of it as studs on lego blocks, you can build with all kinds of lego blocks because they all fit together.

Lego city, space lego, though they’re different sets their studs are all the same.

Now try to click some mechano on to lego. It won’t stay put, the studs, (proteins) won’t fit together.

So all dogs are basically legos, but horses or cows or sheep or corn, different building systems.

All made of plastic but with diffrent kinds of studs to lock in to place.

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Some species are still fairly close, like lions and tigers, horses and donkeys, think of those like Legos and megablocks they’ll fit together, but what you wind up with isn’t really structurally sound.

Because that is more or less how we define species. The most basic definition for species in sexual organisms is that they will not be able to produce fertile offspring.