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1. Oxygen supply capacity in animals evolves to meet maximum demand at the current oxygen partial pressure regardless of size or temperature

   https://doi.org/10.1101/701417  

   Seibel, B. (January 2020, Journal of experimental biology)

   null (Ed.)

   The capacity to extract oxygen from the environment and transport it to respiring tissues in support of metabolic demand reportedly has implications for species’ thermal tolerance, body size, diversity and biogeography. Here, we derived a quantifiable linkage between maximum and basal metabolic rate and their oxygen, temperature and size dependencies. We show that, regardless of size or temperature, the physiological capacity for oxygen supply precisely matches the maximum evolved demand at the highest persistently available oxygen pressure and this is the critical PO2 for the maximum metabolic rate, Pcrit-max. For most terrestrial and shallow-living marine species, Pcrit-max is the current atmospheric pressure, 21 kPa. Any reduction in oxygen partial pressure from current values will result in a calculable decrement in maximum metabolic performance. However, oxygen supply capacity has evolved to match demand across temperatures and body sizes and so does not constrain thermal tolerance or cause the well-known reduction in mass-specific metabolic rate with increasing body mass. The critical oxygen pressure for resting metabolic rate, typically viewed as an indicator of hypoxia tolerance, is, instead, simply a rate-specific reflection of the oxygen supply capacity. A compensatory reduction in maintenance metabolic costs in warm-adapted species constrains factorial aerobic scope and the critical PO2 to a similar range, between ∼2 and 6, across each species’ natural temperature range. The simple new relationship described here redefines many important physiological concepts and alters their ecological interpretation. 

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2. Temperature determines physiological rates and predation in Galápagos rocky reefs

   https://doi.org/10.3354/meps14912  

   Agudo-Adriani, Esteban; Chico-Ortiz, Nicole; Silva, Isabel; Brandt, Margarita; Bruno, John F (August 2025, Marine Ecology Progress Series)

   Water temperature plays a critical role in determining physiological rates in marine ectotherms and influences the strength of ecological interactions. We investigated the effects of temperature on multiple traits of the whelkHexaplex princeps—a common predator in the rocky reefs of the Galápagos, a region characterized by significant temperature fluctuations. We measured metabolic rate, activity levels, prey handling time, and feeding rates across a temperature gradient. First, we conducted respirometry assays to measure the temperature dependence of metabolism. Next, we performed mesocosm experiments to assess how temperature affects predator activity, prey handling time, and feeding rates. Third, we conducted a field experiment to measure predation’s response to seasonal temperature changes. The results from our mesocosms experiment showed a large variation in thermal performance across traits. Nevertheless, all traits exhibit low performance at our coldest experimental temperature with a peak at intermediate temperature, suggesting a unimodal response. Similarly, we observed higher feeding rates in the field at medium temperatures. Our results highlight the importance of temperature in moderating physiological rates and interactions between species, and the challenges of predicting complex ecological processes from individual traits (e.g. metabolic rate, movement, prey handling time). As ocean temperatures continue to rise, understanding how temperature shapes physiological responses across organisms is essential for predicting the future dynamics of marine communities. 

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3. Unique thermal sensitivity imposes a cold-water energetic barrier for vertical migrators

   https://doi.org/10.1038/s41558-022-01491-6  

   Seibel, Brad A.; Birk, Matthew A. (November 2022, Nature Climate Change)

   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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4. Tight spatial coupling of a marine predator with soniferous fishes: Using joint modelling to aid in ecosystem approaches to management

   https://doi.org/10.1111/ddi.13746  

   Roberts, Sarah M.; Jacoby, Ann‐Marie; Roberts, Jason J.; Leslie, Jaelyn; Payne, Khadijah L.; Read, Andrew J.; Halpin, Patrick N.; Barco, Susan; Garrison, Lance; McLellan, William; et al (August 2023, Diversity and Distributions)

   Enrico Pirotta (Ed.)

   Abstract AimUnderstanding the distribution of marine organisms is essential for effective management of highly mobile marine predators that face a variety of anthropogenic threats. Recent work has largely focused on modelling the distribution and abundance of marine mammals in relation to a suite of environmental variables. However, biotic interactions can largely drive distributions of these predators. We aim to identify how biotic and abiotic variables influence the distribution and abundance of a particular marine predator, the bottlenose dolphin (Tursiops truncatus), using multiple modelling approaches and conducting an extensive literature review. LocationWestern North Atlantic continental shelf. MethodsWe combined widespread marine mammal and fish and invertebrate surveys in an ensemble modelling approach to assess the relative importance and capacity of the environment and other marine species to predict the distribution of both coastal and offshore bottlenose dolphin ecotypes. We corroborate the modelled results with a systematic literature review on the prey of dolphins throughout the region to help explain patterns driven by prey availability, as well as reveal new ones that may not necessarily be a predator–prey relationship. ResultsWe find that coastal bottlenose dolphin distributions are associated with one family of fishes, the Sciaenidae, or drum family, and predictions slightly improve when using only fish versus only environmental variables. The literature review suggests that this tight coupling is likely a predator–prey relationship. Comparatively, offshore dolphin distributions are more strongly related to environmental variables, and predictions are better for environmental‐only models. As revealed by the literature review, this may be due to a mismatch between the animals caught in the fish and invertebrate surveys and the predominant prey of offshore dolphins, notably squid. Main ConclusionsIncorporating prey species into distribution models, especially for coastal bottlenose dolphins, can help inform ecological relationships and predict marine predator distributions. 

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5. The past, present, and future of predator–prey interactions in a warming world: Using species distribution modeling to forecast ectotherm–endotherm niche overlap

   https://doi.org/10.1002/ece3.11067  

   Hill, Jessica L; Grisnik, Matthew; Hanscom, Ryan J; Sukumaran, Jeet; Higham, Timothy E; Clark, Rulon W (March 2024, Ecology and Evolution)

   Abstract Climate change has the potential to disrupt species interactions across global ecosystems. Ectotherm–endotherm interactions may be especially prone to this risk due to the possible mismatch between the species in physiological response and performance. However, few studies have examined how changing temperatures might differentially impact species' niches or available suitable habitat when they have very different modes of thermoregulation. An ideal system for studying this interaction is the predator–prey system. In this study, we used ecological niche modeling to characterize the niche overlap and examine biogeography in past and future climate conditions of prairie rattlesnakes (Crotalus viridis) and Ord's kangaroo rats (Dipodomys ordii), an endotherm–ectotherm pair typifying a predator–prey species interaction. Our models show a high niche overlap between these two species (D = 0.863 andI = 0.979) and further affirm similar paleoecological distributions during the last glacial maximum (LGM) and mid‐Holocene (MH). Under future climate change scenarios, we found that prairie rattlesnakes may experience a reduction in overall suitable habitat (RCP 2.6 = −1.82%, 4.5 = −4.62%, 8.5 = −7.34%), whereas Ord's kangaroo rats may experience an increase (RCP 2.6 = 9.8%, 4.5 = 11.71%, 8.5 = 8.37%). We found a shared trend of stable suitable habitat at northern latitudes but reduced suitability in southern portions of the range, and we propose future monitoring and conservation be focused on those areas. Overall, we demonstrate a biogeographic example of how interacting ectotherm–endotherm species may have mismatched responses under climate change scenarios and the models presented here can serve as a starting point for further investigation into the biogeography of these systems. 

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