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Suborbital climatic variability and centres of biological diversity in the Cape region of southern Africa

Huntley, B.; Midgley, G.F.; Barnard, P.; Valdes, P.J.

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Authors

B. Huntley

G.F. Midgley

P. Barnard

P.J. Valdes



Abstract

Aim To explore the magnitude and spatial patterns of last glacial stage orbitally forced climatic changes and suborbital climatic fluctuations in southern Africa, and to evaluate their potential roles in determining present biodiversity patterns. Location Africa south of 15° S. Methods Palaeoclimate scenarios for southern Africa were derived for 17 time slices using outputs from HadCM3 atmosphere–ocean general circulation model experiments, including five designed to mimic Heinrich events. Species distribution models for birds of Karoo (45) or Fynbos (31) were used to simulate species' potential past distributions. Species-richness patterns were assessed for each time slice, and minimum species richness for regional endemics of each biome determined for each grid cell. Areas of greatest ‘stability’ for endemics of each biome were identified using grid cells with greatest minimum richness. Results Simulated suborbital climatic fluctuations were of greater magnitude than orbitally forced changes and had anomalies of opposite sign in many areas. The principal local drivers of suborbital fluctuations were marked contrasts in South Atlantic circulation and temperature between experiments mimicking Heinrich events and those with only slow forcings. These contrasts in ocean circulation and temperature were consistent with marine sediment core evidence of changes in the South Atlantic coincident with Heinrich events in the North Atlantic. Whereas orbitally forced last glacial climates generally resulted in range expansions and increased species richness in many grid cells compared with the present, the contrasting conditions of Heinrich events resulted in much reduced ranges and species richness, especially for Karoo species. Very few grid cells remained suitable for larger numbers of endemic species of either biome under all palaeoclimate scenarios examined, but this minority of ‘stable’ grid cells correspond to present diversity centres. Main conclusions Suborbital climatic fluctuations during the last glacial stage were probably of considerable magnitude in southern Africa. This may account for apparent inconsistencies between regional palaeoclimate records, as well as being key to determining present biodiversity patterns.

Citation

Huntley, B., Midgley, G., Barnard, P., & Valdes, P. (2014). Suborbital climatic variability and centres of biological diversity in the Cape region of southern Africa. Journal of Biogeography, 41(7), 1338-1351. https://doi.org/10.1111/jbi.12288

Journal Article Type Article
Acceptance Date Jan 3, 2014
Online Publication Date Feb 15, 2014
Publication Date Jul 1, 2014
Deposit Date May 19, 2014
Publicly Available Date Mar 29, 2024
Journal Journal of Biogeography
Print ISSN 0305-0270
Electronic ISSN 1365-2699
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 41
Issue 7
Pages 1338-1351
DOI https://doi.org/10.1111/jbi.12288
Keywords Birds, Cape Floristic Province, Endemics, Fynbos, Heinrich events, Hosing experiments, Last glacial stage, South Atlantic, Species distribution models, Succulent Karoo.

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Copyright Statement
This is the peer reviewed version of the following article: Huntley, B., Midgley, G. F., Barnard, P., Valdes, P. J. (2014), Suborbital climatic variability and centres of biological diversity in the Cape region of southern Africa. Journal of Biogeography, 41 (7): 1338–1351 which has been published in final form at http://dx.doi.org/10.1111/jbi.12288. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.





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