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Abstract Tropicalization is a term used to describe the transformation of temperate ecosystems by poleward‐moving tropical organisms in response to warming temperatures. In North America, decreases in the frequency and intensity of extreme winter cold events are expected to allow the poleward range expansion of many cold‐sensitive tropical organisms, sometimes at the expense of temperate organisms. Although ecologists have long noted the critical ecological role of winter cold temperature extremes in tropical–temperate transition zones, the ecological effects of extreme cold events have been understudied, and the influence of warming winter temperatures has too often been left out of climate change vulnerability assessments. Here, we examine the influence of extreme cold events on the northward range limits of a diverse group of tropical organisms, including terrestrial plants, coastal wetland plants, coastal fishes, sea turtles, terrestrial reptiles, amphibians, manatees, and insects. For these organisms, extreme cold events can lead to major physiological damage or landscape‐scale mass mortality. Conversely, the absence of extreme cold events can foster population growth, range expansion, and ecological regime shifts. We discuss the effects of warming winters on species and ecosystems in tropical–temperate transition zones. In the 21st century, climate change‐induced decreases in the frequency and intensity of extreme cold events are expected to facilitate the poleward range expansion of many tropical species. Our review highlights critical knowledge gaps for advancing understanding of the ecological implications of the tropicalization of temperate ecosystems in North America.
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Unique thermal sensitivity imposes a cold-water energetic barrier for vertical migrators
Abstract Alterations of marine species’ ranges with climate change are often attributed to oxygen limitation in warming oceans. Here we report unique metabolic temperature sensitivities for the myriad of vertically migrating oceanic species that daily cross depth-related gradients in temperature and oxygen. In these taxa, selection favours high metabolic activity for predator–prey interactions in warm shallow water and hypoxia tolerance in the cold at depth. These diverging selective pressures result in thermal insensitivity of oxygen supply capacity and enhanced thermal sensitivity of active metabolic rate. Aerobic scope is diminished in the cold, well beyond thermodynamic influences and regardless of ambient oxygen levels, explaining the native distributions of tropical migrators and their recent range expansions following warming events. Cold waters currently constitute an energetic barrier to latitudinal range expansion in vertical migrators. As warming due to climate change approaches, and eventually surpasses, temperatures seen during past warming events, this energetic barrier will be relieved.
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- Award ID(s):
- 2127538
- PAR ID:
- 10373434
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Climate Change
- Volume:
- 12
- Issue:
- 11
- ISSN:
- 1758-678X
- Page Range / eLocation ID:
- p. 1052-1058
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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