Czechia

Freshwater tolerance has evolved multiple times among stickleback fishes (Gasterosteidae), such that several closely related species differ in freshwater tolerance. The threespine and fourspine sticklebacks (Gasterosteus aculeatus and Apeltes quadracus) inhabit both freshwater and saltwater, while the blackspotted stickleback (Gasterosteus wheatlandi) and white threespine ecotype (Gasterosteus aculeatus) are largely restricted to saltwater habitats, despite being able to survive acute freshwater exposure as adults. We investigated whether the distribution of blackspotted and white threespine sticklebacks might be limited by a) their capacity to tolerate freshwater during vulnerable early life stages and/ or b) the winter-induced combined stressors of freshwater and cold temperature. The blackspotted stickleback’s fertilization success decreased by 75% in freshwater relative to saltwater, while the threespine and white threespine sticklebacks maintained similar fertilization success in both salinities. Once fertilized, all four species had high survivorship rates (~100%), similar development rates, and comparable metabolic rates (150-250umolO2/um) in freshwater. Overall, our results suggest that reproduction may limit freshwater colonization in this clade, but early life freshwater tolerance does not. In addition, overwintering of adults in freshwater environments may necessitate energetic expenditure that is unsustainable for non-freshwater-colonizing species. Indeed, a cold-induced decrease to their aerobic scope has been shown to occur in the threespine stickleback. To test whether such energetic limitation might restrict non-freshwater-colonizing species’ distributions, we are currently measuring aerobic scopes of threespine and blackspotted sticklebacks who experienced freshwater and saltwater, under winter (4°C) and summer (18°C) temperatures.

SEB Conference 2024

Does early life freshwater tolerance or adult tolerance of combined stressors limit freshwater colonization in stickleback fishes?

freshwater colonization

cold tolerance

metabolism

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In natural ecosystems, available energy in food often fails to predict biomass production which is also (co)limited by the relative availability of various dietary compounds. Characterizing the link between energy metabolism and the effects of food chemical composition on biomass production thus constitutes a critical step towards better understanding how food quality may affect consumer energy balance and, subsequently, efficiency of energy transfer within food web. Here, we used microcalorimetric approaches to precisely monitor the resting metabolic rate (RMR) of Daphnia magna along ontogeny when undergoing various (non-energetic) nutritional constraints. All types of dietary (co)limitations (Fatty acids, Sterols, Phosphorus) induced an increase in mass-specific RMR up to 128% between highest and lowest quality diets. The strong negative correlation reported here between RMR and growth rate clearly highlight a reallocation of energy from growth to maintenance. The persistence of this correlation regardless of the nature of the nutritional constraints highlight the universality of a trade-off between growth and maintenance under deteriorated nutritional conditions. Ultimately, this energetic cost imposed by food quality on individual RMR may constitute a common metric facilitating the integration of nutritional and metabolic ecology to characterize energy flow within trophic structure.

The energetic cost of food quality: trade-off between growth and maintenance under deteriorated nutritional context.

Anchiornis huxley is a paravian dinosaur that lived in China about 160 million years ago. Their fossils indicate they had wings not only on their forelimbs but also on their hindlimbs. Therefore, they are thought to have glided with both fore and hindlimbs in tandem, which is different from the way the contemporary birds fly. The details of how they used fore and hindlimbs while flying are not clarified yet because the fossil cannot provide the direct information of how they flew during the time they lived. This study tried to give insights into this missing information by using an optimization technique. Genetic algorithm (GA) was used for the optimization of wing configuration parameters and the aerodynamic performance analysis tool XFLR5 was used for the evaluation of aerodynamic performance of individuals. These two tools were used in combination to calculate the optimal wing configuration of individuals under the given condition. As a result, the tandem wing configuration was found to be optimum when the fore wing had weak performance compared to the hind wing. In contrast, the single wing or only fore wing configuration was found to be optimum when the fore wing had the same or better performance than the hind wing. This result indicates how the wing configuration evolved from its original ancestral two-winged or tandem wing configuration to the single-winged one of the contemporary birds as the fore wing improved its aerodynamic performance.

Wing design consideration of feathered dinosaur Anchiornis huxley using GA and aerodynamic performance analysis tool XFLR5

Microplastics (MPs; defined as plastic debris smaller than 5mm) have emerged as one of the fastest-growing forms of pollution across habitats. Environmental pollutants are contributing to the global decline of natural populations, with MPs representing a particularly widespread and persistent threat. The extent to which MPs affect the growth and health of animals remains unclear across various taxa, notably among amphibians, which represent the most endangered group of vertebrates. Here, we used the fully aquatic African clawed frog (Xenopus laevis) to investigate the effects of polyethene MPs on the development and health of its filter-feeding larvae. Xenopus larvae were exposed to an environmentally relevant concentration of MP particles in the absence or presence of exogenous stress hormone corticosterone (CORT), the latter to induce a neuroendocrine stress response. To assess the physiological consequences of MP exposure, our study quantified markers of stress (CORT), or health and ageing (oxidative stress levels and telomere length) in larvae. MP exposure was found to reduce the larval body mass but it did not include changes in the skeletal growth (body length). CORT levels, oxidative stress, and telomere length remained unaltered in larvae exposed to MPs. Our results confirm that environmentally relevant concentrations of MPs reduce body mass but suggest that such effects might not have major consequences for the stress status, health, and ageing rates of filter-feeding amphibian larvae.

The effects of polyethylene microplastic exposure on amphibian larval development and health physiology

Pesticides are indispensable in agriculture and have become ubiquitous in aquatic environments. Pesticides in natural environments can cause many negative impacts on aquatic species, ranging from mortality to sub-lethal physiological and behavioural changes. The complex sub-lethal impacts of pesticides are routinely tested on model species, with zebrafish (Danio rerio) being regularly used as a behavioural model. Although behavioural ecotoxicology research using zebrafish is increasing rapidly, we lack quantitative evidence to support which pesticides have been tested and how study designs are carried out. This shortcoming not only limits the deliberate planning for future primary studies to fill the knowledge gaps but also hinders evidence synthesis. To provide quantitative evidence of what pesticides are currently studied and what study designs are used, we combined a systematic evidence map approach and bibliometric analysis. This novel method has been coined research weaving and allows us to elicit gaps and clusters in our evidence base, whilst showing connections between authors and institutions. The methodology can be summarised in five primary steps: literature searching, screening, extraction, data analysis and bibliometric analysis. We identified four areas where research on the sub-lethal effects of pesticide exposure on zebrafish is lacking. First, some widely used pesticides, such as neonicotinoids, are understudied. Second, most studies do not report important elements of the study design, namely the sex and the life-stage of the zebrafish. Third, some behaviours, such as impacts of pesticide exposure on zebrafish cognition, are underexplored. And last, we revealed through the bibliometric analysis that most of the research is conducted in developed countries and there is limited cross country co-authorships. Upon identifying these gaps, we offer solutions for each limitation, emphasizing the importance of diverse global research output and cross-country co-authorships. Our systematic evidence map and bibliometric analysis provide valuable insights for helping to guide future research, which can be used to help support evidence-based policy decisions.

A systematic evidence map and bibliometric analysis of the behavioural impacts of pesticide exposure on zebrafish.

Birds fold, twist, and spread their wings in flight, leading to dramatic force changes used for their highly manoeuvreble flight. Their finely-tuned shape changes are very challenging to record and study. As a result, little is known about how bird flight is controlled, limiting our bioinspired aircraft designs. Now with motion capture, we have recorded high volume data using captive Harris hawks performing natural flight behaviours. With large, accurate data sets of real morphing shapes we can now use data-driven unsupervised machine learning methods for analyses, including dynamic mode decomposition. Such methods differ from traditional kinematics and from black box AI, leading to both explainable and intuitive results. From these large scale results we can resolve the morphing shape space, model flapping flight dynamics, and can now study the individual techniques and variation of coordinated flight controls.

Shapes and Dynamics of Bird Morphing Flight

Low oxygen concentration events, known as hypoxic events, are naturally occurring but anticipated to become more frequent and severe in the future due to current global changes and anthropogenic pressures. While organisms may adjust their physiology and behaviour in response to hypoxia, better understanding of the link between physiology and behaviour is crucial for predicting the global response of an organism to environmental changes. Even if this link starts to be well known, there is a limited understanding of the genetic basis of it, as well as the potential impact of changing environments on it. Hypoxia, for instance, may modify the correlated evolution between physiology and behaviour by altering the genetic correlation among those traits, what could be important to predict. To address these questions, two populations of Gasterosteus aculeatus were collected from streams already exposed to strong hypoxic events or not. The collected individuals were bred, and half of the offspring were reared either in normoxia (>90% of O2 throughout the day) or hypoxia (>90% of O2 during the day and 30% of O2 during the night to mimic more natural conditions). The growth, swimming capacity, and behaviour (risk-taking and sociability) of the offspring were then measured, and the phenotypic and genetic correlations among the traits estimated. Unravelling the phenotypic and genetic correlations under fluctuating hypoxia can contribute to our understanding of the potential link and evolutionary paths of physiology and behavioural traits facing a changing environment, and the importance of considering that such link may be context dependent.

The missing link: Unravelling the phenotypic and genetic correlation of fish physiology and behaviour under fluctuating hypoxia.

Elevations in atmospheric carbon dioxide (CO2) have been measured by experts for decades. These atmospheric elevations cause changes in aquatic environments as increased CO2 reduces pH. Acidification has been shown to cause changes to the behaviour of many fish species including reducing homing behaviour, foraging behaviour, and predator avoidance. Our study aimed to identify whether elevated levels of CO2 affects the behaviour of Japanese Medaka (Oryzias latipes). To test this, we exposed a total of 300 fish to varying levels of CO2 (2500 µatm, 5500 µatm, 8500 µatm) at varying times (0, 5, 10, 15, 20 d). Two behavioural tests were performed, the first, where we placed individual fish into circular arenas, measured cumulative distance moved, immobility duration, and percent of time spent in the outer zone. For the second test, we placed 6 fish at a time into a small tank where half of the tank was marked with a black line. We then measured the amount of time spent over the line and the number of crosses above the line for individual fish. Our results showed that there were no differences in any behaviour between CO2 treatments; however, there was evidence of acclimation around day 10 in the highest CO2 treatment. Our study suggests that CO2 does not change behaviours of Japanese Medaka, and thus Japanese Medaka may be unaffected by rising atmospheric CO2.

Elevated carbon dioxide does not change behaviour of Japanese Medaka 

University recruitment policies aim to create a diverse and inclusive student community. However, non-traditional students still need help progressing academically (Varga et al., 2021). Academics must reflect on their teaching practices to ensure equitable access to higher education. Additionally, they must consider how students from different backgrounds experience interactions across the institution (Gouvea, 2020).

By recognising how students perceive academic content delivery, especially across various biology disciplines with varying social and professional norms, teaching and research teams can better support student transitions and help them develop their professional and scientific identities within the classroom (Barakabitze et al., 2019). Recognising how these interactions shape a student's scientific and professional identity and the facilitators who provide them is crucial to understanding the breadth of perspectives and identities in the student community (Le et al., 2019; Lieff et al., 2009).

Once these elements are understood, universities are better placed to leverage resources to support the student community and academic transition through the discipline (Brown et al., 2020). When necessary, targeted support should be provided to ensure that students from non-traditional backgrounds have equal access to university education, support non-traditional development, and recognise how students are then influenced in their career trajectory (Wong et al., 2022). Academia must ensure that higher education continues to nurture intellectual growth and face other growing pressures to support an increasingly diverse student community.

Equitable Access to Higher Education: Understanding Student Interactions and Supporting Transitions in Biology Disciplines

Plants are frequently exposed to multiple stresses under field conditions where the occurrence of severe heat waves, flooding, and drought events threaten crop productivity. Thus, investigating the underlying mechanism of plants under combined stresses to find traits of interest for climate-resilient crops is highly demanded. This study in the frame of ADAPT project aimed to investigate the dynamic morphological and physiological responses of potato plants to single and combined abiotic stresses by using an image-based high throughput phenotyping protocol. The applied approach elucidates how plants respond to drought, heat, and waterlogging stresses individually and in combination. Moreover, it enabled the identification of early and late responses. Different responses including plant biomass, photosynthetic efficiency, canopy temperature, and leaf reflectance indices were observed under single and combined stresses. Overall plants were severely affected primarily by waterlogging reflecting the detrimental effect of this stress on potato plants. The drastic reduction in the quantum yield and efficiency of photosystem II was observed with an increase in canopy temperature and water index due to stomatal closure under waterlogging followed by stress combining drought, heat, and waterlogging in combination. The negative impact of stress was reflected in the reduction of final yield. Reduction in the harvest index was observed in all stresses, however severe effect was detected under waterlogging and combined stresses. Here we show that applied phenotyping protocol based on using a combination of multiple imaging sensors is a valuable tool for revealing new insights into understanding plant mechanisms in coping with rapid climate change.

Image-based phenotyping protocol revealed the dynamic responses under combined abiotic stresses in potato plants

An escalating challenge facing Australia’s grain crop production is sustaining the supply of nutritious food within water limited environments. Extreme climate events and decline in available water are threatening crop yield and quality necessitating new solutions to ensure optimal water use within future food systems. We have sought to identify natural biochemical solutions within C4 plants that confer improved responses to carbon assimilation and plant productivity under future climates. We have taken a transgenic approach to overexpress the primary carboxylase of C4 photosynthesis - phosphoenol pyruvate carboxylase (PEPC) in S. viridis and a biochemical approach to investigate the in vitro biochemistry of PEPC across biochemical subtypes within the Paniceae tribe of C4 grasses. We successfully expressed recombinant PEPC isoforms within E. coli and we discovered that PCK PEPC’s were catalytically superior forms and contained an amino acid signature that corresponds to decreased malate inhibition which is crucial for increasing flux through the CCM. Furthermore, structural insight of the PCK PEPC enzyme by Small Angle X-ray Scattering demonstrated that the activator molecule glucose-6-phosphate induces a structural change that is consistent with improved catalysis. Overall, we have identified a number of new avenues to improve carbon in C4 plants particularly under abiotic stress conditions. An update on the current progress of this research will be presented.

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The energetic cost of food quality: trade-off between growth and maintenance under deteriorated nutritional context.

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