The changing course of the Amazon River in the Neogene: center stage for Neotropical diversification

Abstract

We review geological evidence on the origin of the modern transcontinental Amazon River, and the paleogeographic history of riverine connections among the principal sedimentary basins of northern South America through the Neogene. Data are reviewed from new geochronological datasets using radiogenic and stable isotopes, and from traditional geochronological methods, including sedimentology, structural mapping, sonic and seismic logging, and biostratigraphy. The modern Amazon River and the continental-scale Amazon drainage basin were assembled during the late Miocene and Pliocene, via some of the largest purported river capture events in Earth history. Andean sediments are first recorded in the Amazon Fan at about 10.1-9.4 Ma, with a large increase in sedimentation at about 4.5 Ma. The transcontinental Amazon River therefore formed over a period of about 4.9-5.6 million years, by means of several river capture events. The origins of the modern Amazon River are hypothesized to be linked with that of mega-wetland landscapes of tropical South America (e.g. várzeas, pantanals, seasonally flooded savannahs). Mega-wetlands have persisted over about 10% northern South America under different configurations for >15 million years. Although the paleogeographic reconstructions presented are simplistic and coarse-grained, they are offered to inspire the collection and analysis of new sedimentological and geochronological datasets.

Conceptual and empirical advances in Neotropical biodiversity research

“…Biotic interactions such as predation and competition may serve to reduce local richness. Diagram modified from Schluter & Ricklefs (1993) and Albert, Val & Hoorn (in press) .…”

“…Some examples of the constituent disciplines in this pursuit include biology (e.g., community ecology, phylogeography, systematics, taxonomy, historical biogeography; Lomolino, Riddle & Whitakker, 2017 ), geology (e.g., palaeontology, sedimentology, geomorphology), and climatology (e.g., modeling, speleology), amongst others. Successful examples of trans-disciplinary research include the archaeology-ecology synergy that led to the elucidation of pre-Columbian effects on the distribution of Amazonian plants ( Levis et al, 2017 ); the genetic-geology synergy that led to the discovery of an earlier and more prolonged biotic interchange between South and North America since the Miocene ( Bacon et al, 2015 ; De Baets, Antonelli & Donoghue, 2016 ), and the geology-biogeography-systematics synergy that led the discovery of a Miocene origin for the modern transcontinental Amazon river ( Hoorn et al, 2010b ; Albert, Val & Hoorn, in press ). Some of these interactions are already recognized as new sub-disciplines, such as “community phylogenetics” ( Swenson, 2011 ), “geogenomics” ( Baker et al, 2014 ), and “geodiversity” ( Gray, 2004 ).…”

Historical biogeography identifies a possible role of Miocene wetlands in the diversification of the Amazonian rocket frogs (Aromobatidae: Allobates)

“…The Pebas system supposedly occupied most of western Amazonia during a period ranging from early Miocene (23 Mya) to around 10-9 Mya, when this system started to be drained eastward into the Atlantic Ocean (Albert, Val, & Hoorn, 2018). Subsequent hydrological changes have frequently taken place during the Pliocene and the Pleistocene as well, particularly in western Amazonia (Pupim et al, 2019;Rossetti et al, 2015), with various consequences on Amazonian diversification, such as promoting allopatric speciation or favoring dispersals (Albert et al, 2018). These different temporal and spatial contexts may have FPW acknowledge the French/Brazilian GUYAMAZON program action (IRD, CNRS, CTG, CIRAD and Brazilian Fundação de Amparo à Pesquisa do Estado do Amazonas-FAPEAM 062.00962/2018) and co-coordinated by A.…”

Molecular delimitation and taxonomic revision of the wimple piranha Catoprion (Characiformes: Serrasalmidae) with the description of a new species

“…Assuming that the species also occurs in that region, and the occurrence in south‐western Amazon tributaries (Madeira and Purus Rivers), the biogeographic pattern that best explains the distribution of C. mento is the Amazonas‐Paraguay‐Orinoco lowland, also represented by species occurring in the Tocantins‐Araguaia basin, such as Abramites hypselonotus (Vari & Williams, 1987), Curimatella dorsalis (Vari, 1992), Sorubim lima (Littmann, 2007), among others (Dagosta & de Pinna, 2019). In the case of C. absconditus , the observed distribution best fits the eastern Amazon pattern, represented by taxa isolated by the Purus Arch before the formation of the Amazon main channel by the Late Miocene (Albert et al ., 2018; Dagosta & de Pinna, 2019); other examples of the eastern Amazon pattern are Curimatopsis cryptica (Vari, 1982), Synaptolaemus latofasciatus (Britski et al ., 2011), Aphanothorulus emarginatus (Ray & Armbruster, 2016), among others (Dagosta & de Pinna, 2019).…”