The dispersal between Amazonia and Atlantic Forest during the Early Neogene revealed by the biogeography of the treefrog tribe Sphaenorhynchini (Anura, Hylidae)

Abstract

The Amazonia and the Atlantic Forest, separated by the diagonal of open formations, are two ecoregions that comprise the most diverse tropical forests in the world. The Sphaenorhynchini tribe is among the few tribes of anurans that occur in both rainforests, and their historical biogeographic have never been proposed. In this study, we infer a dated phylogeny for the species of the Sphaenorhynchini and we reconstructed the biogeographic history describing the diversification chronology, and possible patterns of dispersion and vicariance, providing information about how orogeny, forest dynamics and allopatric speciation affected their evolution in South America. We provided a dated phylogeny and biogeography study for the Sphaenorhynchini tribe using mitochondrial and nuclear genes. We analyzed 41 samples to estimate the ancestral areas using biogeographical analysis based on the estimated divergence times and the current geographical ranges of the species of Sphaenorhynchini. We recovered three characteristic clades that we recognize as groups of species ( S . lacteus , S . planicola , and S . platycephalus groups), with S . carneus and G . pauloalvini being the sister taxa of all other species from the tribe. We found that the diversification of the tribe lineages coincided with the main climatic and geological factors that shaped the Neotropical landscape during the Cenozoic. The most recent common ancestor of the Sphaenorhynchini species emerged in the North of the Atlantic Forest and migrated to the Amazonia in different dispersion events that occurred during the connections between these ecoregions. This is the first large‐scale study to include an almost complete calibrated phylogeny of Sphaenorhynchini, presenting important information about the evolution and diversification of the tribe. Overall, we suggest that biogeographic historical of Sphaenorhynchini have resulted from a combination of repeated range expansion and contraction cycles concurrent with climate fluctuations and dispersal events between the Atlantic Forest and Amazonia.

Amazonian colonization from the Atlantic Forest: New perspectives on the connections of South American tropical forests

“…We found evidence that vicariance, dispersal and migration after divergence were the major processes responsible for the current genomic diversity and that these processes occurred multiple times during the Quaternary as a result of the emergence of putative forested corridors. Historical demographic models invoke multiple events of connection between AM and AF, supporting the hypothesis that past forest expansions promoted the formation of forested corridors throughout the present-day DD (Auler et al, 2004;Cheng et al, 2013;Dal Vechio et al, 2018;Oliveira et al, 1999;Pereira et al, 2022;Prates, Rivera, et al, 2016;Thomé et al, 2016;Wang et al, 2004). This is also supported by our SDMs projections into the past (LGM and mid-Holocene), which reveal the expansion of wetland areas connecting both regions.…”