Downscaling Last Glacial Maximum climate over southern Africa

Engelbrecht, François; Marean, Curtis W.; Cowling, Richard M.; Engelbrecht, Christien J.; Neumann, Frank; Scott, Louis; Nkoana, Ramapulana; O'Neal, David; Fisher, Erich C.; Shook, Eric; Franklin, Janet; Thatcher, Marcus; McGregor, John L.; Merwe, Jacobus Van der; Dedekind, Zane; Difford, Mark

doi:10.1016/j.quascirev.2019.105879

Cited by 59 publications

(50 citation statements)

References 134 publications

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“…However, by focusing only on Cape clades , which tend to be habitat specialists, we do not fully capture the many habitat generalists associated with widespread clades that are best represented in the eastern CFR (33,39), and which may contribute more to nestedness.…”

Section: Discussionmentioning

confidence: 99%

“…Fourthly, the region shows a pronounced longitudinal gradient in regional-scale (1 -10,000 km 2 ) diversity: The numbers per unit area of taxa associated with clades endemic to the CFR, as well as regional scale richness of entire floras, decline markedly in a longitudinal pattern, from south-west to south-east (32). Fifthly, longitudinal gradients of Pleistocene climatic and biome stability are evident across the CFR, with more stable climates in the west where Mediterranean climates persisted over much of the region, and less stable climates in the east where the CFR flora was replaced at times by a subtropical flora (33)(34)(35).…”

Section: Text Introductionmentioning

confidence: 94%

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Plant richness, turnover, and evolutionary diversity track gradients of stability and ecological opportunity in a megadiversity center

Colville

Beale

Forest

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Research on global patterns of diversity has been dominated by studies seeking explanations for the equator-to-poles decline in richness of most groups of organisms, namely the latitudinal diversity gradient. A problem with this gradient is that it conflates two key explanations, namely biome stability (age and area) and productivity (ecological opportunity). Investigating longitudinal gradients in diversity can overcome this problem. Here we investigate a longitudinal gradient in plant diversity in the megadiverse Cape Floristic Region (CFR). We test predictions of the age and area and ecological opportunity hypotheses using metrics for both taxonomic and phylogenetic diversity and turnover. Our plant dataset includes modeled occurrences for 4,813 species and dated molecular phylogenies for 21 clades endemic to the CFR. Climate and biome stability were quantified over the past 140,000 y for testing the age and area hypothesis, and measures of topographic diversity, rainfall seasonality, and productivity were used to test the ecological opportunity hypothesis. Results from our spatial regression models showed biome stability, rainfall seasonality, and topographic heterogeneity were the strongest predictors of taxonomic diversity. Biome stability alone was the strongest predictor of all diversity metrics, and productivity played only a marginal role. We argue that age and area in conjunction with non–productivity-based measures of ecological opportunity explain the CFR’s longitudinal diversity gradient. We suggest that this model may possibly be a general explanation for global diversity patterns, unconstrained as it is by the collinearities underpinning the latitudinal diversity gradient.

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Section: Discussionmentioning

confidence: 99%

Section: Text Introductionmentioning

confidence: 94%

Plant richness, turnover, and evolutionary diversity track gradients of stability and ecological opportunity in a megadiversity center

Colville

Beale

Forest

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…Focusing on the well-sampled sequence from Boomplaas Cave, we argued—controversially in Thackeray's (2020) opinion—that the micromammals indicated a transition from a relatively humid last glacial maximum (LGM) to a more arid Holocene. This is at odds with earlier interpretations of the region's climate history (e.g., Avery, 1982; Deacon et al, 1984; Deacon and Lancaster, 1988), though it is now supported by a growing body of evidence (e.g., Faith, 2013a, 2013b; Chase et al, 2017, 2018; Engelbrecht et al, 2019). We welcome this opportunity to clarify a few points raised by Thackeray (2020) and to further elaborate on our original interpretations.…”

Section: Introductionmentioning

confidence: 83%

“…Deacon et al (1984) struggled to reconcile this with their interpretations of an arid LGM transitioning to a humid Holocene, though the timing of the hiatus closely matches what we infer to be the most arid portion of the Boomplaas Cave sequence (Faith et al, 2019). In addition, a recent climate simulation suggests that the region would have received greater rainfall during the LGM relative to the present (Engelbrecht et al, 2019). In our view, the consistency within all of these records tips the scale in favor of the emerging understanding of the southern Cape's climate history—the transition from the LGM to the Holocene was characterized by increased aridity.…”

Section: Cutting Through the Confusionmentioning

confidence: 99%

Late Quaternary micromammals and the precipitation history of the southern Cape, South Africa: response to comments by F. Thackeray, Quaternary Research 95, 154–156

2020

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“…The second is a consequence of the unique geography of SA: nowhere else in the world does a MCE transition without any dispersal barriers to a subtropical region. Thus, the CFR has a permeable boundary with the tropics and coastal dunes have provided an effective corridor for tropical lineages to penetrate westwards, especially during mid to late Pleistocene glacials when summer rainfall conditions extended further west in the CFR than they do now (Braun et al, 2019; Engelbrecht et al, in press). This corridor has provided the basis for the unique phylogenetic structure of Cape dune floras.…”

Section: Discussionmentioning

confidence: 99%

Taxonomic, biological and geographical traits of species in a coastal dune flora in the southeastern Cape Floristic Region: regional and global comparisons

Cowling

Logie²,

Brady³

et al. 2019

PeerJ

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In Mediterranean-Climate Ecosystems (MCEs), Holocene coastal dunes comprise small, fragmented and dynamic features which have nutritionally imbalanced and excessively drained, droughty, sandy soils. These characteristics, along with summer drought and salt-laden winds, pose many challenges for plant colonization and persistence. Consequently, MCE dune floras are likely to be distinctive with a high proportion of habitat specialists and strong convergence in growth form mixes. Very little research has compared the species traits of dune floras within and across MCEs. This paper contributes to filling that gap. Here, we analyze the taxonomic, biological and geographical traits for all 402 species in a flora from a dune landscape (Cape St Francis) in the southeastern Cape Floristic Region (CFR) and compare patterns with the trait profiles of other dune floras at a regional (CFR) and global (MCE) scale. Within the CFR, the southeastern (all-year-rainfall) flora at Cape St Francis had a similar trait profile to western (winter-rainfall) dune floras, except for having a lower representation of species belonging to CFR-endemic clades, and higher number of species associated with tropical lineages. The St Francis flora, in common with other CFR and MCE floras, was dominated by members of the Asteraceae, Fabaceae and Poaceae. Some 40% of the St Francis flora was endemic to the CFR, typical of the high rate of MCE-level endemism elsewhere in the CFR, and in other MCEs. About 30% of the flora was confined to calcareous sand, a value typical for many other MCE sites. The St Francis flora, as well as other CFR dune floras, differs from those of other MCEs by having many species associated with shrubby lineages, and by the relatively high incidence of species associated with tropical lineages. The growth form profile of the St Francis and other CFR floras shows strongest similarity with that of Australian MCE dunes in that in both regions, evergreen hemicryptophytes and shrubs share dominance, and annuals are floristically and ecologically subordinate. The least similar of MCEs to the St Francis trait profile is the Mediterranean Basin where annuals are the most frequent growth form while shrubs are subordinate. California and Chile dune floras appear to occupy an intermediate position, in terms of growth form mix, between the Cape and Australia on the one hand, where dune floras have retained features typical of nutrient-poor soils, and the Mediterranean Basin, where dwarf, deciduous shrubs and annuals dominate the life form spectrum. All MCE dunes are threatened by alien plants, infrastructure development, tourism demands and rising sea levels. The high incidence of species of conservation concern in CFR dune floras underestimates the exponentially increasing threats to their habitats, which are already historically at a much-reduced extent. All remaining coastal dune habitat in the CFR, and probably in other MCEs, should be conserved in their entirety.

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Downscaling Last Glacial Maximum climate over southern Africa

Cited by 59 publications

References 134 publications

Plant richness, turnover, and evolutionary diversity track gradients of stability and ecological opportunity in a megadiversity center

Plant richness, turnover, and evolutionary diversity track gradients of stability and ecological opportunity in a megadiversity center

Late Quaternary micromammals and the precipitation history of the southern Cape, South Africa: response to comments by F. Thackeray, Quaternary Research 95, 154–156

Taxonomic, biological and geographical traits of species in a coastal dune flora in the southeastern Cape Floristic Region: regional and global comparisons

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