Potential mammalian species for investigating the past connections between Amazonia and the Atlantic Forest

Abstract

Much evidence suggests that Amazonia and the Atlantic Forest were connected through at least three dispersion routes in the past: the Eastern route, the central route, and the Western route. However, few studies have assessed the use of these routes based on multiple species. Here we present a compilation of mammal species that potentially have dispersed between the two forest regions and which may serve to investigate these connections. We evaluate the present-day geographic distributions of mammals occurring in both Amazonia and the Atlantic Forest and the likely connective routes between these forests. We classified the species per habitat occupancy (strict forest specialists, species that prefer forest habitat, or generalists) and compiled the genetic data available for each species. We found 127 mammalian species presently occurring in both Amazonia and the Atlantic Forest for which, substantial genetic data was available. Hence, highlighting their potential for phylogeographic studies investigating the past connections between the two forests. Differently from what was previously proposed, the present-day geographic distribution of mammal species found in both Amazonia and the Atlantic Forest points to more species in the eastern portion of the dry diagonal (and adjoining forested habitats). The Central route was associated with the second most species. Although it remains to be seen how this present-day geography reflects the paleo dispersal routes, our results show the potential of using mammal species to investigate and bring new insights about the past connections between Amazonia and the Atlantic Forest.

Morphological and genetic diversity in a South American forest‐dependent bat

“…As our molecular chronogram suggests, we speculate that R. pumilio might have originated in southwestern Amazonia (see also Hoorn et al, 2010 andSilva et al, 2019 for other examples among Amazonian vertebrates) and expanded towards the east, almost simultaneously colonizing the north of the Amazonia and the Atlantic Forest. Such a hypothesis seems to confirm the use of a past forest route established between southeastern Amazonia and the northern Atlantic Forest (Coelho et al, 2022;Machado et al, 2021). However, our morphological data indicate northern Amazonian specimens are more similar to the Atlantic Forest than Southern Amazonian specimens.…”

Species limits and recent diversification ofCerradomys(Sigmodontinae: Oryzomyini) during the Pleistocene

“…Based on the recent divergence times obtained for Cerradomys , it is likely that climatic events of the Pleistocene, yielding contraction and expansion of forests, allowed connections between the Atlantic Forest and the Amazon ( Costa, 2003 ; Batalha-Filho et al, 2013 ; Ledo & Colli, 2017 ), forming a barrier and interrupting the gene flow between populations that occupied the central open region. In addition, our results corroborate Tavares, Pessôa & Seuánez (2016) showing that the expansion of the ancestral population that gave rise to C. subflavus and C. goytaca through the Restinga formation may be facilitated by the Cerrado corridor that possibly connected the north of Rio de Janeiro to central Minas Gerais states ( Werneck et al, 2012 ; Machado et al, 2021 ). Posteriorly, climatic oscillation favoured the expansion of the Atlantic Forest, creating a barrier between the population from Restinga ( C. goytaca ) and the population from Minas Gerais ( C. subflavus ).…”

The role of vicariance and dispersal on the temporal range dynamics of forest vipers in the Neotropical region

“…Such corridors, presently composed of relicts of the ancient large forest block, and including gallery forests of the Cerrado and the brejos of the Caatinga [10,16], changed the view that the DODL is a separated and isolated region from both the Amazon and Atlantic forests [10]. Three major corridors have been proposed (see Fig 1) [10,11,26,35]. The Eastern corridor would have connected the northern Atlantic Forest and eastern Amazon through the Caatinga region; the Central corridor would have been located in central Brazil, in the Cerrado region; and the Western corridor would have been located in southwestern South America, including the Chaco, in western Brazil, Paraguay, Bolivia, and Peru [10].…”

“…A recent study, however, suggests more ancient dispersal events through these "young pathways" in the early Miocene [27], 23 to 5 mya. The Western corridor, on the other hand, is hypothesized to be older and more relevant [34,37], despite recent discussions about its importance [35]. The emergence of this corridor was congruent to sea introgressions forming the Pebas system, between 23 and 10 mya [21,38,39], with the expansion of the Amazon basin between 10 and 7 mya [21,38], and with the emergence of the Paraná sea [40,41].…”