Historical connections between Atlantic Forest and Amazonia drove genetic and ecological diversity in Lithobates palmipes (Anura, Ranidae)

Abstract

The Atlantic and Amazon rainforests have a shared but unclear past, with intermittent connections resulting from historical climate change. We investigate these connections by studying the phylogeography and climatic niche of the disjunct distributed frog Lithobates palmipes. We sequenced two fragments of mitochondrial DNA from Atlantic Forest (AtF) and Amazonia (AmF) individuals and evaluated how genetic diversity is distributed in space and whether past demographic changes occurred. Also, we evaluated the existence of past suitable connections between biomes for L. palmipes through ecological niche models (ENM) and tested for niche divergence. The AtF group is nested within the AmF group and closely related to individuals from eastern Amazonia, a pattern recovered in many species that used northeast connection routes. We found evidence of recurrent use of connections in different directions and time during the Pleistocene, resulting in genetic structure between biomes, with no signal of demographic change and evidence of niche divergence across both genetic groups. ENMs indicated suitable areas connecting forests throughout northeastern Brazil during the Pleistocene. Mitochondrial lineages do not match biomes exactly. One lineage is composed of AtF populations and eastern Amazonia individuals. The other is composed of western Amazonia individuals, suggesting an effect of past climatic heterogeneity within the Amazonia forest. This is the first evidence that this route drove genetic and ecological diversity for amphibians recently, a group with habits and ecological requirements different from other vertebrates that have been shown to use this putative corridor.

Key words:

• Demography
• lineage delimitation
• Lithoboates
• Neotropics
• Niche divergence
• Pleistocene
• rainforests

Acknowledgments

This study was funded in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001 (FEAC 88887.342842/2019-00). We thank curators and manager staff of the Museum of Natural History of the Federal University of Alagoas (MUFAL), Herpetological Collection of the University of Brasília (CHUNB), Herpetological collection of the Federal University of Paraíba (CHUFPB), Herpetological Collection of the Cariri Regional University (URCA – H), Herpetological Collection of the Federal University of Mato Grosso do Sul (MAP-T), Amphibians and Reptiles (INPA-H) and Genetic Resources (CRG, INPA-HT) collections from the National Institute of Amazonian Research (INPA), and Herpetological collection of São Paulo University (USP) for donating tissue samples. We are thankful to Thais Ferreira Araújo for her help during the early stages of laboratory analysis. We also thank Leandro Alves da Silva for collecting tissues, Antoine Fouquet for sharing DNA sequences, Marcelo Gehara, Vanessa Staggemeier and Tamí Mott for comments and suggestions on the manuscript. FPW thanks Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq (Productivity Fellowship: 311504/2020-5) and the L’Oréal-UNESCO For Women In Science Program.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental material

Supplemental material for this article can be accessed here: https://doi.org/10.1080/14772000.2022.2046657.

Associate Editor: Dr Nadia Bystriakova

Additional information

Funding

This work was supported in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001, under grant 88887.342842/2019-00; Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq (Productivity Fellowship: 311504/2020-5, 310942/2018-7); and L’Oréal-UNESCO For Women In Science Program (IRT 2017).