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Climatic shifts drove major contractions in avian latitudinal distributions throughout the Cenozoic

Saupe, Erin E. and Farnsworth, Alexander and Lunt, Daniel J. and Sagoo, Navjit and Pham, Karen V. and Field, Daniel J. (2019) Climatic shifts drove major contractions in avian latitudinal distributions throughout the Cenozoic. Proceedings of the National Academy of Sciences of the United States of America, 116 (26). pp. 12895-12900. ISSN 0027-8424. PMCID PMC6601418. doi:10.1073/pnas.1903866116.

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Many higher level avian clades are restricted to Earth’s lower latitudes, leading to historical biogeographic reconstructions favoring a Gondwanan origin of crown birds and numerous deep subclades. However, several such “tropical-restricted” clades (TRCs) are represented by stem-lineage fossils well outside the ranges of their closest living relatives, often on northern continents. To assess the drivers of these geographic disjunctions, we combined ecological niche modeling, paleoclimate models, and the early Cenozoic fossil record to examine the influence of climatic change on avian geographic distributions over the last ∼56 million years. By modeling the distribution of suitable habitable area through time, we illustrate that most Paleogene fossil-bearing localities would have been suitable for occupancy by extant TRC representatives when their stem-lineage fossils were deposited. Potentially suitable habitat for these TRCs is inferred to have become progressively restricted toward the tropics throughout the Cenozoic, culminating in relatively narrow circumtropical distributions in the present day. Our results are consistent with coarse-scale niche conservatism at the clade level and support a scenario whereby climate change over geological timescales has largely dictated the geographic distributions of many major avian clades. The distinctive modern bias toward high avian diversity at tropical latitudes for most hierarchical taxonomic levels may therefore represent a relatively recent phenomenon, overprinting a complex biogeographic history of dramatic geographic range shifts driven by Earth’s changing climate, variable persistence, and intercontinental dispersal. Earth’s current climatic trajectory portends a return to a megathermal state, which may dramatically influence the geographic distributions of many range-restricted extant clades.

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Additional Information:© 2019 National Academy of Sciences. Published under the PNAS license. Edited by Nils Chr. Stenseth, University of Oslo, Oslo, Norway, and approved May 7, 2019 (received for review March 8, 2019). We thank Michelle Casey (Towson University) for advice on paleo-plate rotation models. E.E.S. was supported by a Division of Earth Sciences National Science Foundation Postdoctoral Fellowship and Leverhulme Grant DGR01020. A.F. and D.J.L. were funded by United Kingdom National Environmental Research Council Grants NE/K014757/1, NE/I005722/1, NE/I005714/1, and NE/P013805/1. E.E.S. and D.J.F. contributed equally to this work. Author contributions: E.E.S. and D.J.F. designed research; E.E.S. and D.J.F. performed research; A.F., D.J.L., and N.S. contributed new reagents/analytic tools; E.E.S. and K.V.P. analyzed data; and E.E.S. and D.J.F. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. Data deposition: Data from this study have been deposited on the online data archive Zenodo (DOI: 10.5281/zenodo.2658119). This article contains supporting information online at
Funding AgencyGrant Number
NSF Postdoctoral FellowshipUNSPECIFIED
Leverhulme TrustDGR01020
Natural Environment Research Council (NERC)NE/K014757/1
Natural Environment Research Council (NERC)NE/I005722/1
Natural Environment Research Council (NERC)NE/I005714/1
Natural Environment Research Council (NERC)NE/P013805/1
Subject Keywords:climate change; niche conservatism; latitudinal diversity gradient; ecological niche modeling; historical biogeography
Issue or Number:26
PubMed Central ID:PMC6601418
Record Number:CaltechAUTHORS:20190610-142615245
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Official Citation:Climatic shifts drove major contractions in avian latitudinal distributions throughout the Cenozoic. Erin E. Saupe, Alexander Farnsworth, Daniel J. Lunt, Navjit Sagoo, Karen V. Pham, Daniel J. Field. Proceedings of the National Academy of Sciences Jun 2019, 116 (26) 12895-12900; DOI: 10.1073/pnas.1903866116
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96253
Deposited By: Tony Diaz
Deposited On:10 Jun 2019 21:34
Last Modified:16 Feb 2022 23:07

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