Chorology

CHOROLOGY. - The term c. (from χάρα, earth, and λάγος, discourse) denotes the study of the geographical distribution of living beings: thus, zoogeography is distinguished for animals and phytogeography for plants. This distribution and dispersal of faunas and floras depends primarily on present-day or ecological factors, that is, on the present existence of suitable climatic and environmental conditions; however, it also depends on historical or geographical factors, that is, on the geological and climatic vicissitudes undergone by the earth’s crust throughout its history. Thus, separations of continents and islands, occurring in given geological eras, may account for the absence or presence of particular zoological groups, according to the period in which they appeared on earth; and changes in climatic conditions may explain the reductions or fragmentation of the areas of distribution of many species which in the past had a more extensive geographical distribution. Human action, too, may considerably alter the distribution of faunas and floras.