The GABI in Southern South America

Abstract

The Great American Biotic Interchange (GABI) between North and South America is one of the most important events in the history of land mammals. The interchange occurred in several phases during more than nine million years. We here analyze the chronology and dynamics of the GABI, the evolution of some South American mammalian groups through time, and the Quaternary mammalian extinctions. As the GABI was a complex process, we divide it into ProtoGABI and GABI 1 to 4. In our concept, the extinction of the megafauna by the gatherer/hunters that entered South American during the latest Pleistocene is a part of the GABI. The putative scarce frequency of extinct mammals in archeological sites is discussed. The evolutive relevance of the GABI is reflected in that half of the species living in South America had a North American ancestry. A final process, not included in the GABI, is the remarkable alteration of ecosystems by modern man. Presently, the composition and distribution of almost all autochthonous land mammal faunas are changing dramatically. Moreover, frequently they are replaced with domesticated and/or wild exotic species. Short History of the Interchange and the Great American Biotic Interchange (GABI) ConceptThe first authors to acknowledge the interchange of land vertebrates between the Americas and the resulting "mixed faunas" were Wallace (1876) The GABI in Southern South America originally devoid of mammals and was populated from North America, followed by in situ differentiation that was facilitated by its isolation during the "tertiary" (Morrone 2011). Patterson and Pascual (1972) carried out a deep analysis of the South American fossil mammalian faunas throughout the Cenozoic. These authors suggested that competition and extinction occurred during the interchange. Pascual and Fidalgo (1972) and Webb (1976), among others, proposed a similar scenario. Since this suggestion, there was considerable debate as to whether placental carnivores arriving from North America actually caused the extinction of South American marsupial carnivores by competitive displacement (see Prevosti et al. 2013).The expression "Great American Biotic Interchange" (GABI) or "Gran Intercambio Biótico Americano" (GIBA) was proposed by Webb (1985a). The denomination referred to a biogeographic process that lasted a relatively short time. Actually, Webb (1985b) suggested that during the "Uquian" (presently Marplatan), 8 mammal families of Holarctic origin suddenly appeared in South American. This was demonstrated incorrect by Tonni et al. (1992) and Cione and Tonni (1995). Moreover, Woodburne (2010) restricts the GABI almost exclusively to the Pleistocene interchange (after 2.8 Ma) as a consequence of the establishment of a permanent dry land conexion between South and Central America.During the 1980 decade, intense paleontological study helped to clarify the evolution and integration of the mammalian communities in South America (see Simpson 1980;Reig 1981;Hoffstetter 1981;Marshall et al. 1979Marshall et al. , 1982Marsha...

Systematic revision and redefinition of the genus Scirrotherium Edmund and Theodor, 1997 (Cingulata, Pampatheriidae): Implications for the origin of pampatheriids and the evolution of the South American lineage including Holmesina

“…The biogeographical correlation across the Isthmus of Panama using S. antelucanus has insightful implications for the understanding of the late Cenozoic intercontinental migratory dynamics in the Americas, including the Great American Biotic Interchange (GABI) (Webb 2006; Woodburne et al 2006; Woodburne 2010; Cione et al 2015; Bloch et al 2016). Noteworthy, this is the first transisthmian biogeographical correlation for a Neogene terrestrial mammal at the level of species; furthermore, it is the first short-distance intercontinental correlation (i.e.…”

“…This pattern has prevented the exploration of possible early or intermediate phases of anagenetic/cladogenetic events in late Cenozoic Interamerican migrant taxa, which in turn it is reflected in the fact that we are detecting “suddenly” well-differentiated terminal taxa (e.g. Holmesina ) in marginal, distant areas with respect to the Central American Seaway and adjacent terrains (Cione et al 2015 and references therein).…”

“…From these events, only the latter, based on the fossil record of H. floridanus , is included in the GABI. The remaining two events are classified as part of the macroevolutionary invasion “wastebasket” called “Pre-GABI” (literally, ‘before the GABI’; Woodburne et al 2006; Woodburne 2010; also named by Cione et al 2015 as “ProtoGABI”). In the lineage Plaina - Pampatherium , it was differentiated one genus, Pampatherium , and at least three species ( P. mexicanum , P. typum and P. humboldtii , being the two latter recorded in South America).…”

The Neogene Record of Northern South American Native Ungulates

“…9 mya and from North to South America by ca. 7 mya (Webb, 2006;Woodburne, 2010;Leigh et al, 2014;Cione et al, 2015;O'Dea et al, 2016). Other studies using dated molecular phylogenies across a wide range of taxa in addition to mammals indicate that an important part of the interchange predated ca.…”

“…However, in San Gregorio so far only one of the ten described mammalian taxa is an immigrant from North America, the procyonid Cyonasua (Forasiepi et al, 2014). The age of San Gregorio corresponds to the Ensenadan SALMA (Figure 28), of which the type locality is located in La Plata county (~34° S) in Argentina (Cione et al, 2015). In southern South America, this time interval is characterized by the presence of several clades of Holarctic origin (e.g., Cervidae, Ursidae, Tapiridae, Felidae, and Gomphotheriidae; Cione et al, 2015), which contrasts with the pattern observed in the Falcón Basin.…”