Belgium

Understanding thermal physiology is critical for predicting population shifts due to climate change. During heatwaves, fish are particularly vulnerable due to increased energy demands and reduced oxygen levels in warmer waters. Current perceptions of heatwave risks often focus on short-term mortalities, neglecting fitness effects associated with sub-lethal physiological constraints.
In Atlantic salmon (Salmo salar), age at maturity, a key life-history trait, is genetically linked to aerobic scope — an essential metabolic attribute for energy allocation. Energy allocation is highly responsive to environmental temperatures, but how do different life history genotypes respond to heatwave temperatures?
First, we present a thermal performance curve for aerobic scope for juvenile salmon after acclimation. We also examine physiological differences between two vgll3 genotypes, which are linked to early or late maturation in adult salmon. We measured specific dynamic action, the metabolic cost of digestion and food assimilation, and aerobic scope of salmon juveniles at 15 and 20 °C to observe how fish manage energy expenditure as temperatures rise.
This study has significant implications for understanding the fitness of Atlantic Salmon and linking the effects of heatwaves to their life history and physiological fitness. Variation in how different genotypes respond to non-optimal temperatures allows for more accurate predictions of how populations may change in terms of genotypic structure and behaviour. This research is crucial for understanding evolutionary responses to climate change and for developing conservation strategies, both globally and within Finnish waters.

SEB Conference 2025

Is thermal performance during heatwaves predicted by life history genotypes in salmon?

heatwaves

salmon

ecophysiology

technical paper

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Climate change is anticipated to drive both temperature and atmospheric water levels beyond the physiological tolerances of many species, with potentially cascading effects on animal populations that vary based on their life-history characteristics. Even closely related species may show divergent responses to climate change depending on their ecological strategies. We investigated how nesting behavior influences climate adaptation by comparing two bee genera: stem-nesting Ceratina and ground-nesting Lasioglossum. Specimens were collected across a 3,000 km latitudinal gradient in Japan, spanning sub-arctic to sub-tropical climates. We experimentally tested thermal (critical thermal maximum/minimum) and hygric traits (desiccation resistance, water loss rate), comparing tolerances to local temperature and vapor pressure deficit (VPD). Our results revealed that stem-nesting bees maintained broader physiological tolerances, while ground-nesting species showed significantly higher rates of water loss, especially in high-VPD regions (low latitude). Ground nesters also exhibited narrower thermal safety margins that decreased with latitude. These patterns likely reflect adaptation to different microclimate variability in nesting sites, with stable underground conditions potentially selecting against high thermal and desiccation stress tolerance. While ground-nesting bees can behaviorally thermoregulate within their burrows, their lower physiological plasticity—particularly their reduced desiccation resistance—may limit their ability to forage during extreme temperature events. Our findings emphasize that desiccation tolerance, during periods of high thermal stress, may be a critical determinant of pollinator vulnerability to climate change. Understanding how nesting strategies and other life-history traits mediate species' responses to climate change will be essential for predicting and protecting pollinator populations.

Life-history strategy and local adaptation shape resilience to climate change in bees

It has been proposed that larger individuals within fish species may be more sensitive to global warming, as a result of limitations in their capacity to provide oxygen for aerobic metabolic activities. This could affect size distributions of populations in a warmer world but requires investigation. We studied four groups of individuals over a ~10-fold range in mass (20 – 800 g overall), two farmed species, Nile tilapia (Oreochromis niloticus) and European seabass (Dicentrarchus labrax), and two species captured in the wild, European seabass and gilthead seabream (Sparus aurata). In all groups, capacity to provide oxygen for aerobic activities (Absolute Aerobic Scope) was independent of mass at their acclimation temperature. Tolerance of acute warming, however, declined significantly with mass in all groups, when evaluated as the critical temperature for fatigue from aerobic swimming (CTSmax ). The CTSmax  protocol challenges a fish to meet the oxygen demands of constant aerobic exercise while their metabolic demands are accelerated by incremental warming, until fatigue. The maximum rates achieved prior to fatigue declined very significantly with mass. Mass-related variation in CTSmax  and maximum oxygen uptake rates were positively related in all groups, which may indicate a causal relationship. When fish populations are faced with acute thermal stress, larger individuals may become constrained in their ability to perform aerobic activities at lower temperatures than smaller conspecifics. This could affect survival and fitness of larger fish in a future world with more frequent and extreme heatwaves, with consequences for population productivity.

Evidence that tolerance of acute warming declines with increasing body mass in fishes

Environmental stressors such as chemical and light pollution can have detrimental effects on the fitness of animals. One proposed link between these stressors and survival are telomeres, which play an important role in genome protection, ageing and somatic maintenance and are known to be shortened due to harsh environmental conditions. Amphibians are especially susceptible to environmental stressors because of their permeable skin and complex life cycle, characterized by metamorphosis from larvae to adults, making them an ideal model species to investigate possible effects of anthropogenic disturbance on telomere length. Therefore, we test the effects of chemical and light pollution on the telomere dynamics of the European green toad (Bufotes viridis) from larval stage until adulthood, in controlled lab experiments as well as in field studies in and around Vienna. We are developing a real-time quantitative polymerase chain reaction (qPCR) assay to analyze the relative telomere length (RTL) from DNA swabs from the larval, juvenile and adult stages. This longitudinal approach to understanding telomere dynamics of amphibians is the first one of this kind and the results will broaden our understanding about how anthropogenic disturbance acts on wildlife on a molecular basis and will therefore help to further improve animal conservation.

Telomere dynamics of the European green toad (Bufotes viridis) in the context of urbanization and pollution

DNA microsatellites are small tandem repeats within the genome, which are ideal for individual identification and paternity.  While this technique was developed for use in crime-scene investigations, it is now regularly used to aid in animal breeding, conservation efforts, and field research. For example, microsatellites are often used to determine chick paternity, which helps determine which chicks resulted from extrapair copulations (EPCs).
We generated DNA microsatellites profiles for all male and female quail (Coturnix coturnix) within our breeding colony. To evaluate sperm donor identity only, we removed the blastodisc from the PVM prior to gDNA isolation. Sperm donor identity was determined by generating MS profiles from PVMs to exclude females and non-contributing males.
We were able to successfully exclude all but one male in 50% of the eggs analyzed using four MS primer sets. We expect that adding more MS primer sets will allow us to successfully identify the male donor in all eggs.
Because studbooks are mostly based on pairings and not genetic testing, paternity in colony managed populations may not be accurate depending on EPC rates, making studbooks paternity inaccurate. Using this method, EPC rates for specific colonies or species can be analyzed allowing facilities to determine whether the costs of chick paternity testing is justified.
Unlike chick paternity, this method shows all sperm donors present at the oocyte membrane which could significantly impact captive management and our understanding of basic avian reproductive physiology, including cryptic female choice and sperm storage tubule function, and behaviors such as EPCs.

Detection of perivitelline-bound sperm donor identity using DNA microsatellites analysis: A tool for extrapair and cryptic mate choice evaluation

Reproduction, particularly lactation, is one of the costliest energetic processes for mammals. During this period, females must allocate energy to offspring growth and development while also sustaining their own metabolic requirements. In an income breeder like roe deer (Capreolus capreolus), particularly during the early hider phase, energy requirements of the mother, and hence foraging and ranging behaviour, increase substantially to support fawn growth. Using biologging data from 90 GPS-collared reproductive female roe deer over a 17-year period, we investigated activity patterns linked to foraging during three key phases of reproduction (late gestation, early lactation, late lactation until weaning) to determine how the energy- and time- budgets were related to reproductive outcomes (number of fawns at weaning). We found that activity peaked during the first month post-parturition with a predicted increase in daily time spent active from 48% pre-parturition to 56% during peak lactation. The number of fawns at weaning explained some of the variation in both timing and intensity of activity: females with one or two fawns were more active overall, particularly during mid-day, compared to those with no fawns at weaning. Females with two fawns had higher activity levels, although not doubled, than those with just one. Our preliminary results therefore suggest that females with two fawns either acquire energy more efficiently, or face a trade-off between maintenance and allocation to fawn growth. Further investigations will elucidate these potential trade-offs, allowing us to better map the relationship between energetic constraints and reproductive outcome in this income breeder.

Linking activity patterns and reproductive outcome in an income breeder

Suspension feeders, organisms that retain food particles from water, have recently become of interest to inspire engineered filtration systems aiming for higher efficiency, energy savings, and reduced clogging. Among the 35 known suspension feeding mechanisms, only a few have been explored in detail for a biomimetic transfer, and even fewer have progressed to successful prototypes, patents, and commercial products. Based on my research of invertebrate and vertebrate suspension feeders, I experienced several challenges during the identification, analysis and transfer of biological particle separation processes. For example, constraints such as availability, protection statuses, and size posed difficulties when examining organisms like flamingos, manta rays, and whale sharks. A significant challenge was encountered in analysing the role of mucus in particle adhesion and transport in ascidians. Flow tank experiments using artificial mucus demonstrated limited particle retention capabilities compared to natural mucus. Despite these obstacles, promising results were achieved with ram-feeding fish. By integrating morphological, behavioural, and fluid-dynamical analyses, a prototype filter was developed with a self-cleaning mechanism capable of retaining 97.5% of microplastic fibres in a controlled lab environment. These findings underscore the potential of the biomimetic approach not only to advance filtration technology but also to deepen our understanding of these organisms, thereby supporting their conservation.

Overcoming Challenges in Studying Filter-Feeders for Bio-Inspired Filtration

The steroid hormone cortisol plays a crucial role in our response to stress, influencing various physiological systems, including the brain and immune system. These effects are mediated by two receptors: the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR). Both function as ligand-activated transcription factors, binding as homodimers to response elements in target genes. While MR and GR have been shown to form heterodimers, the physiological significance of MR/GR heterodimerization remains largely unexplored. In recent studies, we have demonstrated that MR/GR heterodimerization is essential for specific cortisol-driven effects on behaviour and immune function. To investigate this, we developed mutant MRs and GRs that could selectively form homo- or heterodimers and we expressed these receptors in zebrafish larvae from an MR/GR double knockout line. Behavioral analysis revealed that cortisol-induced hyperactivity occurred only under conditions of MR/GR heterodimerization. Similarly, cortisol’s inhibition of macrophage migration during inflammation also depended on heterodimer formation. To identify molecular targets of the MR/GR heterodimers, we next performed RNA-sequencing. Our findings showed that the heterodimers regulate distinct gene expression patterns. For example, genes involved in glutamatergic signalling were regulated, which was confirmed by CRISPR/Cas9-mediated gene editing of a response element in the gene encoding the metabotropic glutamate receptor 3, which abolished the cortisol-induced hyperactivity. In summary, our research establishes the physiological relevance of MR/GR heterodimerization in vivo, highlighting its central role in eliciting cortisol-induced responses to stress.

Mineralocorticoid and glucocorticoid receptor heterodimers drive distinct cortisol-induced stress responses

GCN2 is an evolutionarily conserved serine/threonine protein kinase that acts as a sensor of amino acid deficiency and phosphorylates eIF2α; this inhibits global translation initiation but allows expression of ATF4 and activation of the integrated stress response (ISR). Here we show that we show that eight different inhibitors of the RAF protein kinases (RAFi) paradoxically activate GCN2 leading to eIF2α -dependent (and ERK1/2-independent) ATF4 and CHOP expression. The GCN2 kinase inhibitor A-92, GCN2 RNAi, GCN2 knock-out or ISRIB (an eIF2α antagonist) all reverse RAFi-induced expression of ATF4 and CHOP indicating that RAFi require GCN2 to activate the ISR.  RAFi also activate full-length recombinant GCN2in vitroand in cells. Activation of the ISR by RAFi is abolished by a GCN2 kinase dead mutation, whilst a M802A gatekeeper mutant is activated at lower RAFi concentrations, demonstrating that RAFi bind directly to the GCN2 kinase domain; this is supported by mechanistic structural models of RAFi interacting with GCN2.  RAFi may therefore serve as novel probes for GCN2 function in the ISR and proteostasis. Our results may also be relevant to the clinical use of RAFi in cancer.

A novel class of small molecule activators of GCN2, an amino acid-sensing protein kinase

Co-creation of the curriculum with student partners fosters a greater sense of ownership and belonging to a course and has been widely linked to positive outcomes in terms of professional development and employability skills. With expanding student numbers across the sector and a demand for modern laboratory skills and techniques from employers, it’s important that we are able to keep pace with developing authentic, contemporary lab classes, providing our students with the up-to-date skills required by employers. To be effective, these classes need to evolve year on year, placing increasing demands on staff. With expanding numbers of students, it is also becoming harder to provide enough wet, final year projects due to limitations of lab capacity and available staff supervisors. Here we present a scalable solution which incorporates co-creation of the curriculum with final year student partners as part of our final year project provision.
We will present the results of the first pilot study which has successfully designed and embedded a new laboratory class into level 3 of the neuroscience degree here at Glasgow. The contemporary lab is then linked to a summative assessment, which also evolves with the lab provision year on year, providing a connectedness to real world challenges and employer demands.
We intend to scale the approach to meet the increased capacity and supervision demands for final year wet projects. We will show how we can offer multiple group projects, co-creating multiple different laboratory classes with no increased demand on supervision.

A scalable and sustainable model for co-creating laboratory classes and improving employability skills in the Life Sciences sector.  

Water scarcity, impacted by climate change, threatens grapevine production and quality. To select varieties more adapted to constraining conditions, a key lever could be to explore genetic progress margins around the well-known trade-off between carbon gain and water loss. A major bottleneck that hampers such advances is the lack of methods for measuring fine functioning traits on thousands of plants as required for genetic analyses, and easily usable in field settings. To overcome this limitation, we deployed an original approach to predict photosynthesis, water-use efficiency and other constitutive leaf traits using high-throughput measurements of poro-fluorometry and near-infrared spectroscopy on a grapevine diversity panel of 250 cultivars grown both in a greenhouse with different watering regimes, and in the vineyard. All these cultivars were resequenced, yielding 1.6M genomic variants, which were used to perform genome-wide association studies with single-locus linear mixed-model and LocalScore algorithms. We found large genetic variability for all traits studied in the greenhouse, with genomic heritability ranging from 0.14 to 0.38. Thirty-six QTLs were detected, with some co-localizations, such as a main genomic region associated with net photosynthesis, electron transport rate, and transpiration. Interestingly, additional regions were detected, specifically associated with either photosynthesis or transpiration, highlighting genetic margins to maintain photosynthesis under drought together with a lower water use. Our findings provide valuable insights into how photosynthesis responds to multiple environmental factors in field settings. This is particularly relevant for perennial crops such as grapevine, where cumulative effects of adverse conditions over years deserve major attention.

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Life-history strategy and local adaptation shape resilience to climate change in bees

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