The members of a race have similar morphological, physiological, and ecological characteristics and are distributed in a region that is part of the range of the species or subspecies. Various races are often found in the same locality, but they are differentiated by their living conditions (ecological race). Thus, many plant species include an alpine race, a xeromorphic race, and a race that requires shade. Among animals, there are seasonal races of crustaceans. Many races of parasites are distinguished by their functional adaptation (specialization) to certain plant or animal hosts (races based on hosts). In ichthyology the term “race” refers to local populations (schools) of fish.