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1. A multimillennial climatic context for the megafaunal extinctions in Madagascar and Mascarene Islands

   https://doi.org/10.1126/sciadv.abb2459  

   Li, Hanying; Sinha, Ashish; Anquetil André, Aurèle; Spötl, Christoph; Vonhof, Hubert B.; Meunier, Arnaud; Kathayat, Gayatri; Duan, Pengzhen; Voarintsoa, Ny Riavo; Ning, Youfeng; et al (October 2020, Science Advances)

   null (Ed.)

   Madagascar and the Mascarene Islands of Mauritius and Rodrigues underwent catastrophic ecological and landscape transformations, which virtually eliminated their entire endemic vertebrate megafauna during the past millennium. These ecosystem changes have been alternately attributed to either human activities, climate change, or both, but parsing their relative importance, particularly in the case of Madagascar, has proven difficult. Here, we present a multimillennial (approximately the past 8000 years) reconstruction of the southwest Indian Ocean hydroclimate variability using speleothems from the island of Rodrigues, located ∼1600 km east of Madagascar. The record shows a recurring pattern of hydroclimate variability characterized by submillennial-scale drying trends, which were punctuated by decadal-to-multidecadal megadroughts, including during the late Holocene. Our data imply that the megafauna of the Mascarenes and Madagascar were resilient, enduring repeated past episodes of severe climate stress, but collapsed when a major increase in human activity occurred in the context of a prominent drying trend. 

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2. A new interpretation of Madagascar's megafaunal decline: The “Subsistence Shift Hypothesis”

   https://doi.org/10.1016/j.jhevol.2019.03.002  

   Godfrey, Laurie R.; Scroxton, Nick; Crowley, Brooke E.; Burns, Stephen J.; Sutherland, Michael R.; Pérez, Ventura R.; Faina, Peterson; McGee, David; Ranivoharimanana, Lovasoa (May 2019, Journal of Human Evolution)
3. Causes and Consequences of Pleistocene Megafaunal Extinctions as Revealed from Rancho La Brea Mammals

   https://doi.org/10.1016/j.cub.2019.06.059  

   DeSantis, Larisa R.G.; Crites, Jonathan M.; Feranec, Robert S.; Fox-Dobbs, Kena; Farrell, Aisling B.; Harris, John M.; Takeuchi, Gary T.; Cerling, Thure E. (August 2019, Current Biology)

   The fossils preserved in the Rancho La Brea “tar” seeps in southern California span the past ∼50,000 years and provide a rare opportunity to assess the ecology of predators (e.g., the American lion, sabertooth cats, cougars, dire wolves, gray wolves, and coyotes), including clarifying the causes and consequences of the terminal Pleistocene extinction event. Here, a multi-proxy approach elucidates dietary responses of carnivorans to changing climates and megafaunal extinctions. Using sample sizes that are unavailable anywhere else in the world, including hundreds of carnivoran and herbivore specimens, we clarify the paleobiology of the extinct sabertooth cats and dire wolves—overturning the idea that they heavily competed for similar prey. Canids (especially the dire wolf) consumed prey from more open environments than felids, demonstrating minimal competition for prey throughout the latest Pleistocene and largely irrespective of changing climates, including just prior to their extinction. Coyotes experienced a dramatic shift in dietary behavior toward increased carcass utilization and the consumption of forest resources (prey and/or plant resources) after the terminal Pleistocene megafaunal extinction. Extant predators’ ability to effectively hunt smaller prey and/or utilize carcasses may have been a key to their survival, especially after a significant reduction in megafaunal prey resources. Collectively, these data suggest that dietary niches of carnivorans are not always static and can instead be substantially affected by the removal of top predators and abundant prey resources. 

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4. Plant biomes demonstrate that landscape resilience today is the lowest it has been since end‐Pleistocene megafaunal extinctions

   https://doi.org/10.1111/gcb.15299  

   Wang, Yue; Shipley, Benjamin R.; Lauer, Daniel A.; Pineau, Rozenn M.; McGuire, Jenny L. (August 2020, Global Change Biology)

   Abstract Resilient landscapes have helped maintain terrestrial biodiversity during periods of climatic and environmental change. Identifying the tempo and mode of landscape transitions and the drivers of landscape resilience is critical to maintaining natural systems and preserving biodiversity given today's rapid climate and land use changes. However, resilient landscapes are difficult to recognize on short time scales, as perturbations are challenging to quantify and ecosystem transitions are rare. Here we analyze two components of North American landscape resilience over 20,000 years: residence time and recovery time. To evaluate landscape dynamics, we use plant biomes, preserved in the fossil pollen record, to examine how long a biome type persists at a given site (residence time) and how long it takes for the biome at that site to reestablish following a transition (recovery time). Biomes have a median residence time of only 230–460 years. Only 64% of biomes recover their original biome type, but recovery time is 140–290 years. Temperatures changing faster than 0.5°C per 500 years result in much reduced residence times. Following a transition, biodiverse biomes reestablish more quickly. Landscape resilience varies through time. Notably, short residence times and long recovery times directly preceded the end‐Pleistocene megafauna extinction, resulting in regional destabilization, and combining with more proximal human impacts to deliver a one‐two punch to megafauna species. Our work indicates that landscapes today are once again exhibiting low resilience, foreboding potential extinctions to come. Conservation strategies focused on improving both landscape and ecosystem resilience by increasing local connectivity and targeting regions with high richness and diverse landforms can mitigate these extinction risks. 

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5. Climate change extinctions

   https://doi.org/10.1126/science.adp4461  

   Urban, Mark C (December 2024, Science)

   Climate change is expected to cause irreversible changes to biodiversity, but predicting those risks remains uncertain. I synthesized 485 studies and more than 5 million projections to produce a quantitative global assessment of climate change extinctions. With increased certainty, this meta-analysis suggests that extinctions will accelerate rapidly if global temperatures exceed 1.5°C. The highest-emission scenario would threaten approximately one-third of species, globally. Amphibians; species from mountain, island, and freshwater ecosystems; and species inhabiting South America, Australia, and New Zealand face the greatest threats. In line with predictions, climate change has contributed to an increasing proportion of observed global extinctions since 1970. Besides limiting greenhouse gases, pinpointing which species to protect first will be critical for preserving biodiversity until anthropogenic climate change is halted and reversed. 

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