Climate and humans set the place and time of proboscidean extinction in late quaternary of South America
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2013-10-30
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The late Quaternary extinctions have been widely debated for a long time, but the varying magnitude of
human vs. climate change impacts across time and space is still an unresolved question. Here we assess
the geographic range shifts in response to climate change based on Ecological Niche Models (ENMs) and
modeled the timing for extinction under human hunting scenario, and both variables were used to explain
the extinction dynamics of Proboscideans during a full interglacial/glacial cycle (from 126 ka to 6 ka) in
South America. We found a large contraction in the geographic range size of two Proboscidean species studied
(Cuvieronius hyodon and Notiomastodon platensis) across time. The largest contractions of their geographical
ranges occurred in the northern part of South America, where we previously reported no
evidence of coexistence among earliest humans and non-sloth megafauna, including Proboscideans. Our results
herein support a strong effect of climatic changes on geographical range dynamics of Proboscideans
throughout late Quaternary, although this does not fully support climate change as the single cause of
their extinctions. We show that both Proboscideans were narrowly distributed on scattered patches of suitable
habitats (i.e., refugia) around 11 ka, period in which the earliest humans potentially arrived in South
America, increasing the population density thereafter. Under this overall unsuitable climatic condition at
11 ka, both Proboscideans would be extinct after around 550 years of human hunting, but if climatic conditions
were suitable like in Last Glacial Maximum (LGM), the time-for-extinction would be at least 3 times
longer under the same human hunting pressures. Thus, our findings support the “Broken Zig-Zag” model
and show that South American Proboscideans might have been completely extinct due to human impacts
during periods of climate crisis. We conclude, in agreement with an increasing body of evidence in the recent
literature, that the late Quaternary megafaunal extinction event was the result of additive effects from
different stressors, and that the relative magnitude of these impacts vary across space and time. Indeed, climate
changes set the place where the Proboscideans were extinct in South America, whereas the humans
set the time of these extinctions.
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Late quaternary extinctions, Climate change, Human impact, Multiple causes, Broken zig-zag model, Ecological niche models
Citação
LIMA-RIBEIRO, Matheus Souza; NOGUÉS-BRAVO, David; TERRIBILE, Levi Carina ; BATRA, Persaram; DINIZ-FILHO, José Alexandre Felizola. Climate and humans set the place and time of proboscidean extinction in late quaternary of South America. Palaeogeography, Palaeoclimatology, Palaeoecology, v. 392, p. 546-556, 2013. Disponível em:< http://www.sciencedirect.com/science/article/pii/S0031018213004641>.