Mimicry is a trait which exists in nature generally as a defense mechanism.  It can be used in a variety of ways, but generally these are broken down into three categories.  Does real life mimicry relate at all to comic book mimicry?  Well not really, in fact the terms which are used are not even compatible.  Mimicry in comics usually refers to copying powers, whereas mimicry in nature refers to copying appearance (which puts this in the realm of shapechangers mostly).  Anyway I will try to use an example of what each type of mimicry might be closely related to in comics:

Batesian mimicry

Batesian mimicry basically involves one species copying the traits of another in order to make it seem more dangerous than it really is.  This is common with insects that mimic the colouring of monarch butterflies.  Predators that know the monarch is poisonous leave anything alone which looks like a monarch.  As near as I can tell this is basically what most comic book shapechangers use their powers for.   They generally use it to become a copy of something, which may be not dangerous, but which humans have already a preformed opinion of (especially if it is a friend.)  

 
Mullerian Mimicry

This is a warning system where two or more species have a similar warning system, thus forming a redundant system of warnings.  This doesn’t exist per se in comic book shapechangers (at least not as I can tell) but in a sense it does apply in a different way.  Many heroes have similar costume (X-Men, Green Lanterns, the Superman Family, the Bat family, Diana/Donna/Cassie, the Flashes, various versions of Captain or Iron Man) and so the emblem or appearance on one is known in a specific sense as it applies to all.   Most villains going up someone with the super “S” probably know they are in for a hard battle.  Interestingly this happens most with heroes and not so much with villains (though it applies to certain ones like Manhunters.)

 
Emsleyan/Mertensian Mimicry

This is not such a well understood form of mimicry where a more dangerous animal mimics a less dangerous one.   This is probably because it is giving predators a symbol that it is dangerous only and not deadly, thus not killing the predators (it is not always desirable that predators die.)  As far as this works it doesn’t really pertain to comics.  The closest would probably be supernatural creatures (demons, vampires) that take on the appearance of a human, but this is not usually designed to keep humans alive rather to better scheme against them.   A character like Martian Manhunter might fall into this category as well.