These Cows Better Get to Evolving! - Minecraft: The Evolution Update

This is the ultimate depiction of what a Minecraft Evolution Update can truly be

Picture this: a Cow sits in a plains biome right where its species has evolved, yet all of a sudden a player comes and steals the mob for themselves. Where could this cow be going!? Well, this doesn't just happen to cows; it happens to a lot of mobs, and more often than not, they're sent far away into a new biome where they have yet to adapt. In base Minecraft, these mobs breed through generations upon generations, yet no changes happen. Imagine the cow I'm referring to, but in a world where these changes really happen. The cow is taken to a snowy taiga, and generations pass, which slowly cause it to transform into the Highland cattle depiction.

Of course, it's not limited to Cows but may expand to various mobs. Additionally, special items may be dropped from these evolved animals based on biomes. Although these items should not be major, only small additions that may combine to make something decorative, possibly items that can be used to make "rare" potions, etc. This is what I would call "Minecraft: The Evolution Update" Imagine a world where regular mob breeding still matters even after late game! Of course, I do think there should be restrictions on doing this. The items should vary in challenge. 

Thank you for your consideration.