Question: What animal subject to the Foster's rule is the smallest North American deer?

Related documents: [0]  [DOC] The Key deer ("Odocoileus virginianus clavium") is an endangered deer that lives only in the Florida Keys. It is a subspecies of the white-tailed deer ("O. virginianus"). It is the smallest North American deer. [END] 
[1]  [DOC] Foster's rule (also known as the island rule or the island effect) is an ecogeographical rule in evolutionary biology stating that members of a species get smaller or bigger depending on the resources available in the environment. 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. [END]  
Answer: Key deer
Key deer