El Gran Intercambio Biótico Americanouna revisión paleoambiental de evidencias aportadas por mamíferos y aves neotropicales

Resumo

Under classical point of view, the formation of the Panama Isthmus during Pliocene (3 Ma ago) would have allowed the species interchange between North America and South America. This ecological and evolutionary process named Great American Biotic Interchange (GABI) would be determinant in the configuration of the current american biota. This process began to be studied with information from the fossil record in diverse taxa (especially mammals). Furthermore, information from extant species, biogeographic aspects, phylogenetical analysis, a constant growing of fossil record, as well as a significant increase in the geological knowledge of the zone, have allowed us to propose scenarios for a high complexity GABI processes and suggest a scenario of less isolation for South America during the Cenozoic. The most recent evidence derived from studies in birds and mammals point to multiple colonization events since the late Oligocene with the entry of some bird groups, and later along the Miocene with the colonization of lineages in both taxa, these events were previous to what has usually been considered for the interchange process. The fully established GABI is constituted by 4 phases along the Plio-Pleistocene, in each one of them, different waves of colonization were presented between both continents in a great diversity of lineages. Also during Pleistocene-Holocene several processes of extinction were evidenced, the explanation of which were the determining factors in these processes have been cause of debate, this aspect is discussed in our paper, showing through the evidence an important paradigm with explanations based on the relevance of paleogeographic factors and environmental changes in the adaptation processes to biomes. Thus, we leave the classical idea of ecological competition between northern and southern species. In conclusion, the process turns out to be a complex network of biotic interactions conditioned mainly by changing abiotic factors during the paleoenvironmental configuration of the Americas.