Shifting ecosystem connectivity during the Pleistocene drove diversification and gene-flow in a species complex of Neotropical birds (Tityridae: Pachyramphus)

Author(s)

Musher, Lukas J. ^{[1, 2]} ; Galante, Peter J. ^[3] ; Thom, Gregory ^[1] ; Huntley, Jerry W. ^[1] ; Blair, Mary E. ^[3]

Affiliation

^[1] Amer Museum Nat Hist, Dept Ornithol, Cent Pk West 79th St, New York, NY 10024 - USA

^[2] Amer Museum Nat Hist, Richard Gilder Grad Sch, Cent Pk West 79th St, New York, NY 10024 - USA

^[3] Amer Museum Nat Hist, Ctr Biodivers & Conservat, New York, NY 10024 - USA

• Document type: Journal article
• Source: Journal of Biogeography; v. 47, n. 8 APR 2020.
• Web of Science Citations: 0

Abstract

Aim We aim to test the biogeographic drivers of diversification and gene-flow at the Isthmus of Panama using a species complex of suboscine birds as a case study. We specifically evaluate whether diversification in these birds is better explained by continuous parapatry or a Refuge Model of periodic isolation and gene-flow due glacial cycling. Location The Isthmus of Panama (Neotropics). Taxon Pachyramphus aglaiae and Pachyramphus homochrous (Aves: Tityridae). Methods We develop an approach to distinguish among the two biogeographic hypotheses-parapatric ecological speciation versus climatically mediated speciation-by making explicit predictions for demographic history, niche evolution and change in geographic connectivity over time. We sequenced genome-wide markers (ultraconserved elements) to estimate the evolutionary and demographic history of this group. We applied both phylogenomic network analyses and demographic modelling using a supervised machine learning approach. These genetic analyses were combined with a novel distribution modelling method that estimates the probability of interspecies contact as a function of climatic conditions through time. Results We found that both spatial and genetic analyses revealed concordant results. All speciation events occurred during the Pleistocene and were characterized by non-continuous gene-flow, supporting a scenario of climate-mediated diversification. Spatial connectivity was highest at present, consistent with our best demographic model of secondary contact. Main conclusions This study exemplifies a mechanism by which speciation, dispersal and introgression unfold in an important region for Neotropical diversification-the Isthmus of Panama-where periods of both isolation and introgression probably drive diversification. Overall, our results are consistent with the Refuge Model of biotic diversification, but suggest that introgression may be a crucial yet underappreciated component of this classic paradigm. (AU)

• FAPESP's process: 12/50260-6 - Structure and evolution of the Amazonian biota and its environment: an integrative approach
• Grantee: Lúcia Garcez Lohmann
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 18/17869-3 - Comparative phylogeography of montane bird species from southern Atlantic Forest: Integrating evolutionary and ecological traits in the study of community assemblage
• Grantee: Gregory Thom e Silva
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 17/25720-7 - Comparative phylogeography of montane bird species from southern Atlantic Forest: Integrating evolutionary and ecological traits in the study of community assemblage
• Grantee: Gregory Thom e Silva
• Support Opportunities: Scholarships in Brazil - Post-Doctoral