Novos rumos da biogeografia
This article is a brilliant lecture given in the In-Service Training course for Secondary Level Teachers of Geography by Professor Melo Leitão, technical consultant of the Brazilian National Council of Geography. It is entitled "New Destinations of Biogeography."
He demonstrates that Biogeography is a science. The great difficulty in the way of widening studies in this field have arisen, he says, principally from its relationship to Biology, on the one hand, and to Geography on the other". He defines the subject as follows: "Biogeography is the study of the biologic covering of the earth as a function of the climate and of the barriers or bridges which induce expansion or isolation of living creatures." Presenting the close relationships of Biogeography with six other sciences (Fig. 1), he declares: "no living creature can be considered as an isolated entity in nature". He develops a chart to compare the phytogeographic principles of Goon, Mason and Clain with the general principles of Biogeography, and comes to the conclusion that they are identical. Subsequently he studies the nine biogeographic principles which he summarizes as· follows:
Climate of primary influence; Ecobiosis, of great importance in the study of dwelling places. but of secondary and negligible significance in Biogeography; Allelobiosis, the study of general and constant relationships among living creatures; Migration, making a distinction between mass immigration and periodic immigration; Fixation, which study he approaches by first defining the biogeographic concept of area as "every portion of the terrestrial surface to which any taxonomic unity is linked"; Expansion, signifying widening of an area or district which conserves its same biotic characteristic, that is, the same fauna and flora distribution; Variation, as distinct from variability, and constituting, "as it were, the material and static translation of variability"; Selection, the formation of new subspecies under the impact of va1iability and migration; and Stabilization, "the fixation of any taxonomic unity in a determined area necessarily signifying stabilization of that taxonomic unity or at least some one of its; subdivisions.
He closes the articles showing "by brief and incisive examples", the practical importance of Biogeography in hygiene, agriculture and in pre-historic and paleontological studies.