To recent papers
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The deep-time dynamics of the latitudinal diversity gradient (LDG), especially through dramatic events like mass extinctions, can provide invaluable insights into the biotic responses to global changes, yet they remain largely underexplored. Our study shows that the shape of marine LDGs changed substantially and rapidly during the Permian-Triassic mass extinction from a modern-like steep LDG to a flat LDG. The flat LDG lasted for ~5 My and was likely a consequence of the extreme global environment, including extreme warming and ocean anoxia, which ensured harsh conditions prevailing from the tropics to the poles. Our findings highlight the fundamental role of environmental variations in concert with severe biodiversity loss in shaping the first-order biogeographic patterns.
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.
News:
Extreme environmental conditions can lead to a massive global reshuffling of biodiversity
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High-resolution stable isotope (Î18O and Î13C) sclerochronology of accretionary carbonate bivalve shells can provide subannual environmental records useful for understanding intervals of extinction, which are commonly periods of rapid change and instability. Here, we present results from high-resolution serial sampling of Lahillia larseni bivalve shells across the Cretaceous-Paleogene boundary (KPB) on Seymour Island, Antarctica. These data highlight two intervals of anomalous Î18O and Î13C values that coincide with condensed fossil last occurrences: one at the KPB and one at an apparent extinction event 150 k.y. earlier. We interpret these two intervals to represent periods of both climate warming, as indicated by lower Î18O, and seasonal anoxia or euxinia, as evidenced by anomalously low (â21.6â to â3.0â VPDB [Vienna Peedee belemnite]) Î13C values with high (2â to 19â in magnitude) seasonal variation. Low-oxygen conditions may have acted as a kill mechanism at the earlier extinction interval and possibly prolonged recovery from the KPB extinction.
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