Island gigantism is a more specific aspect of a theory that describes how animals evolve larger bodies, The smallest North American deer subject to the theory is the Key deer pusblished in 1965.
 For example, it is known that pygmy mammoths evolved from normal mammoths on small islands. Similar evolutionary paths have been observed in elephants, hippopotamuses, boas, deer (for example Key deer) and humans. 
 It is the smallest North American deer. 
 Island gigantism is one aspect of the more general "island or Foster's rule", which posits that when mainland animals colonize islands, small species tend to evolve larger bodies, and large species tend to evolve smaller bodies. 
