Why isn't there any different pony tribe couples and when there is one...

[cider float 2,538]

Why isn't there any different pony tribe couples and when there is one they think it's weird that they had an alicorn baby? Not sure if Cadance and Shining Armor count as a different pony tribe couple though since Cadance could of been an unicorn prior to becoming an alicorn and alicorns could just be an unicorn with wings. 

 

Further the question can griffons, dragons and ponies mate with one another and produce offspring? The way they treat each other like another intelligent anthropomorphic being wouldn't this rule be allowed?

[Nara 84]

From a purely biological and scientific point fo view interspecies offsprnings won't happen cause it's basically impossible... but it's a fantasy world so let's roll with it for a moment 

I'm guessing maybe such offsprings are rare since most species tend to stick to their own kind and they live in specific societies and ecosystems. If they do occur they might be infertile so that way we don't see a bunch of mixed species creatures. What would such a creature even look like after a few generations of interspecies breeding?   

[Tropical Melody 6,457]

Just to confuse the issue further, a same tribe couple can also give rise to a unicorn, or whatever, so that is possible too, and there is an example, the Cakes. The unicorn offspring is Pumpkin, while both parents are earth ponies. Mr. Carrot Cake, I think it was, did say that this is because there is a unicorn somewhere in his ancestry. In biological terms this is called an atavism or "evolutionary throwback".

Edited November 22, 2016 by Tropical Melody

[GrimGrimoire 4,973]

Well it is a fantasy world, so it is possible something like that could happen.. except it is ruled by Hasbro and they are not that comfortable with the idea of baby making in general much less by way of inter-species breeding. I would not be surprised though if they did not at least try to touch upon the idea of love between them though. They have touched upon crushes enough... so I can see them maybe taking some of those ideas a bit further, but not much further.