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Flat latitudinal diversity gradient caused by the Permian-Triassic mass extinction - PubMed

  • ️Wed Jan 01 2020

Flat latitudinal diversity gradient caused by the Permian-Triassic mass extinction

Haijun Song et al. Proc Natl Acad Sci U S A. 2020.

Erratum in

Abstract

The latitudinal diversity gradient (LDG) is recognized as one of the most pervasive, global patterns of present-day biodiversity. However, the controlling mechanisms have proved difficult to identify because many potential drivers covary in space. The geological record presents a unique opportunity for understanding the mechanisms which drive the LDG by providing a direct window to deep-time biogeographic dynamics. Here we used a comprehensive database containing 52,318 occurrences of marine fossils to show that the shape of the LDG changed greatly during the Permian-Triassic mass extinction from showing a significant tropical peak to a flattened LDG. The flat LDG lasted for the entire Early Triassic (∼5 My) before reverting to a modern-like shape in the Middle Triassic. The environmental extremes that prevailed globally, especially the dramatic warming, likely induced selective extinction in low latitudes and accumulation of diversity in high latitudes through origination and poleward migration, which combined together account for the flat LDG of the Early Triassic.

Keywords: biodiversity; biogeography; end-Permian mass extinction; global warming; ocean anoxia.

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Conflict of interest statement

The authors declare no competing interest.

Figures

Fig. 1.
Fig. 1.

LDGs for late Permian and Triassic intervals. (A) Subsampled diversity using a quota of 380 occurrences for each time interval. Vertical bar presents the SD. (B) SQS diversity with a quorum level of 0.5. Dashed line represents the discontinuous case.

Fig. 2.
Fig. 2.

Rarefied genus-level diversity trends related to latitude from the late Permian to the end of the Triassic. Data are standardized by repeatedly subsampling from a randomly generated set until reaching a quota of 136 occurrences in each time bin at each latitudinal interval (

SI Appendix, Table S3

). Diversities are drawn as a contour map by using Origin Pro-2017 software. Ch, Changhsingian; Gr, Griesbachian; Di, Dienerian; Sm, Smithian; Sp, Spathian; An, Anisian; La, Ladinian; Ca, Carnian; No, Norian; Rh, Rhaetian.

Fig. 3.
Fig. 3.

Extinction and extirpation magnitudes in the Changhsingian and early Griesbachian interval and origination and invasion magnitudes in the late Griesbachian–Smithian interval. (A) The combined rates of extinction–extirpation and origination–invasion. (B) Extinction and extirpation rates in the Changhsingian and early Griesbachian interval. (C) Origination and invasion rates in the late Griesbachian-Smithian interval. Vertical bars represent SEs.

Fig. 4.
Fig. 4.

Biotic and environmental changes throughout the late Permian to the Middle Triassic. (A) SQS diversities across latitudinal zones. (B) Genus richness and proportion of nekton (23). (C) The number of sites yielding metazoan reefs (50). (D) Sea-surface temperature (SST), ocean redox, and continental weathering. SST values are derived from conodont oxygen isotope data (

SI Appendix, Table S6

and

Dataset S2

). Redox states of seawater are from conodont Th/U ratios (20). Riverine-to-mantle Sr flux ratios (FR/FM) calculated from conodont Sr isotopes reflect continental weathering change (43).

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