Speculative Fact #216: Sneaky Sneaky Evolution

Sympatric speciation: Where a new species branches off from its parent in the same geographic location. It's  a controversial theory that puts an additional wrinkle into the already convoluted process of evolution, since generally it's thought that a new species is a result of isolation from its parent species until they can no longer reproduce with each other. 

Not only has this kind of fungi farming ant evolved a new species but done so in the same extremely small area, forming a perilous parasitic relationship with its parent species. 
    We continue to find new ways for life to diversify.  Could you apply this idea to your own story? What would be the consequence of other species, human or otherwise, changing in such a subtle way? How would they be different from their parents? How would they hide it?

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