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

Saupe, EE and Farnsworth, A and Lunt, DJ and Sagoo, N and Pham, KV and Field, D. 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 Online ISSN 1091-6490 DOI https://doi.org/10.1073/pnas.1903866116

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Official URL: https://www.ncbi.nlm.nih.gov/pubmed/31182570

Abstract

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.

Item Type: Article
Uncontrolled Keywords: 2019AREP; IA75
Subjects: 04 - Palaeobiology
Journal or Publication Title: Proceedings of the National Academy of Sciences of the United States of America
Volume: 116
Page Range: pp. 12895-12900
Identification Number: https://doi.org/10.1073/pnas.1903866116
Depositing User: Sarah Humbert
Date Deposited: 25 Nov 2019 17:32
Last Modified: 25 Nov 2019 17:32
URI: http://eprints.esc.cam.ac.uk/id/eprint/4575

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