Can deer of different species interbreed?

In Russia, they have interbred species of deer, but the morph they create has health issues, short lifespans and are sterile and cannot reproduce, lest there would be a new species of deer.

Some can, some can't. Key deer can't interbreed with mule deer.

Depends on how closely they are related to each other. In many cases, different species can produce fertile offspings, but since each species has a different way of life, the hybrids may be poorly equipped to live the same way as either parent because they have genes from 2 different species and they may then act in a way that is intermediate between the two species. Because of that hybrids often fail to survive and that in turn means that different species, if they can avoid interbreeding with each other, are better off if they do so. Indeed that is what we see in nature. Even though some species can successfully interbreed, they rarely do because doing so will result in having a bigger chance of being eliminated from the gene pool. Some species evolve different identification marks, or calls or phermones to have them avoid interbreeding. It is these signals that also help humans identify them as different species. The whitetail for example has a different colored tail than the blacktail deer. That helps them avoid interbreeding across species lines in all likelihood.

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"Whitetail are the oldest living species of deer at 3.5 million years old. The blacktail deer ( Odocoileus hemionus ) split off from the whitetail at some time in the past, thought to be a million years ago or more. The blacktail and the whitetail are different species.

The blacktail deer then split off a subspecies, the mule deer (Odocoileus hemionus hemionus), which is the youngest living deer species, arising 10,000 years ago. So the blacktail and mule deer are the same species, but the mulie is a subspecies of the blacktail, and they are both close cousins to the whitetail.

Of course nothing is ever simple, and there is a complicated three way relationship, found by mitochondrial DNA evidence, that the making of the mule deer involved some crossing back of the whitetail to the blacktail deer.

The two species do not normally interbreed in a natural setting, but will if kept confined together. The hybrids do well in captivity, but in the wild they rarely survive because they do not know how to follow the successful survival strategies of either parent, and so are vulnerable to predators."

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There are some that have done so. See the list below.

http://www.macroevolution.net/deer-hybrids.html

Yes, they can breed.

and you care ? why ?

incest is illegal