Browsing by Author "Peralta-Maraver, Ignacio"

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    Long-term forecast of thermal mortality with climate warming in riverine amphipods
    (2023) Verberk, Wilco C. E. P.; Hoefnagel, K. Natan; Peralta-Maraver, Ignacio; Floury, Mathieu; Rezende, Enrico L.
    Forecasting long-term consequences of global warming requires knowledge on thermal mortality and how heat stress interacts with other environmental stressors on different timescales. Here, we describe a flexible analytical framework to forecast mortality risks by combining laboratory measurements on tolerance and field temperature records. Our framework incorporates physiological acclimation effects, temporal scale differences and the ecological reality of fluctuations in temperature, and other factors such as oxygen. As a proof of concept, we investigated the heat tolerance of amphipods Dikerogammarus villosus and Echinogammarus trichiatus in the river Waal, the Netherlands. These organisms were acclimated to different temperatures and oxygen levels. By integrating experimental data with high-resolution field data, we derived the daily heat mortality probabilities for each species under different oxygen levels, considering current temperatures as well as 1 and 2? warming scenarios. By expressing heat stress as a mortality probability rather than a upper critical temperature, these can be used to calculate cumulative annual mortality, allowing the scaling up from individuals to populations. Our findings indicate a substantial increase in annual mortality over the coming decades, driven by projected increases in summer temperatures. Thermal acclimation and adequate oxygenation improved heat tolerance and their effects were magnified on longer timescales. Consequently, acclimation effects appear to be more effective than previously recognized and crucial for persistence under current temperatures. However, even in the best-case scenario, mortality of D. villosus is expected to approach 100% by 2100, while E. trichiatus appears to be less vulnerable with mortality increasing to 60%. Similarly, mortality risks vary spatially: In southern, warmer rivers, riverine animals will need to shift from the main channel toward the cooler head waters to avoid thermal mortality. Overall, this framework generates high-resolution forecasts on how rising temperatures, in combination with other environmental stressors such as hypoxia, impact ecological communities.
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    Temperature adaptation and its impact on the shape of performance curves in Drosophila populations
    (2023) Alruiz, Jose M.; Peralta-Maraver, Ignacio; Bozinovic, Francisco; Santos, Mauro; Rezende, Enrico L.
    Understanding how species adapt to different temperatures is crucial to predict their response to global warming, and thermal performance curves (TPCs) have been employed recurrently to study this topic. Nevertheless, fundamental questions regarding how thermodynamic constraints and evolution interact to shape TPCs in lineages inhabiting different environments remain unanswered. Here, we study Drosophila simulans along a latitudinal gradient spanning 3000 km to test opposing hypotheses based on thermodynamic constrains (hotter-is-better) versus biochemical adaptation (jack-of-all-temperatures) as primary determinants of TPCs variation across populations. We compare thermal responses in metabolic rate and the egg-to-adult survival as descriptors of organismal performance and fitness, respectively, and show that different descriptors of TPCs vary in tandem with mean environmental temperatures, providing strong support to hotter-is-better. Thermodynamic constraints also resulted in a strong negative association between maximum performance and thermal breadth. Lastly, we show that descriptors of TPCs for metabolism and egg-to-adult survival are highly correlated, providing evidence of co-adaptation, and that curves for egg-to-adult survival are systematically narrower and displaced toward lower temperatures. Taken together, our results support the pervasive role of thermodynamics constraining thermal responses in Drosophila populations along a latitudinal gradient, that are only partly compensated by evolutionary adaptation.
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    Warm acclimation reduces the sensitivity of Drosophila species to heat stress at ecologically relevant scales
    (John Wiley and Sons Inc, 2025) Baeza Icaza, Amalia; Poblete Ahumada, Gabriela Antonia; Rezende Landaeta, Enrico; Peralta-Maraver, Ignacio
    Thermal acclimation is presumed to affect heat tolerance, though it is unclear how this should impact populations under realistic natural conditions. In this study, we quantified how thermal acclimation affects heat tolerance landscapes in Drosophila and, as a consequence, their predicted mortality in the field based on modelling with a dynamic thermal tolerance algorithm. We measured the thermal tolerance of four Drosophila species (D. repleta, D. hydei, D. simulans and D. virilis) acclimated to five constant temperatures covering a range from 18 to 30°C. We then combined this information with field temperatures to construct dynamic tolerance landscapes for these species and examine how survival varies over the course of a year. Our analyses reveal the effect of acclimation on an ecologically relevant scale, specifically through the study of cumulative mortality under natural thermal regimes. We explore how different species respond to thermal challenges during acclimation, generally showing an increase in critical temperature (CTmax) while either reducing or maintaining constant thermal sensitivity (z). Furthermore, we show that while acclimation presents a relatively modest improvement in thermal tolerance during short ramping laboratory trials, this response becomes stronger when tolerance estimates are translated into ecologically relevant timescales, such as annual survival. Our results indicate that acclimation to warm conditions can substantially increase Drosophila thermal tolerance, contradicting the idea that thermal acclimation in ectotherms has only a minor effect. Our work applies novel approaches to studying thermal tolerance and aims to highlight the role of acclimation in ameliorating the impact of global warming.