Biology subjects

Burraco, P.

Publications and source records attributed to Burraco, P..

10 recordsLinked to original sources

bioRxiv2026

Beyond harm: synthesising meta-analytical and mechanistic evidence on animal responses to microplastics

A central question in ecology and evolution is determining when environmental challenges translate into stress and biological harm. Human-derived pollutants are often assumed to be inherently damaging; however, their effects may depend strongly on ecological and physiological context. Microplastics exemplify this complexity, eliciting heterogeneous responses across taxa rather than uniform toxicity. Here, we synthesise evidence from 14 meta-analyses encompassing 9,101 effect sizes to identify the conditions under which microplastic exposure leads to damage, neutrality, compensation, or stimulation. These syntheses reveal clear negative effects alongside frequent neutral outcomes and occasional stimulatory responses. Microplastic effects vary with particle characteristics and exposure conditions and are strongly moderated by species-specific traits and life stage. We further argue that plasticity in the gut and in behavioural and physiological traits may buffer microplastic effects. Emerging evidence also indicates that biofilm colonisation alters the physicochemical and biological properties of microplastics, potentially modifying their ecological interactions and toxicity profiles. By reframing microplastics as context-dependent challenges rather than universally toxic agents, we provide a conceptual framework for understanding animal responses under realistic ecological conditions and identifying the biological and environmental contexts in which microplastic exposure is most likely to result in harm.

ecology↗

bioRxiv2026

Ontogenetic consequences of developmental temperature in amphibians: simultaneous gains in heat tolerance and cumulative costs to stress physiology

Heat tolerance is critical for ectotherms facing environmental temperature variability, yet how it varies across life stages, and whether trade-offs occur between temperature-induced developmental plasticity and heat tolerance, remain unclear, particularly in organisms undergoing metamorphosis which represent 95% of all animal species. We examined how early-life thermal conditions shape growth, development, survival, acclimation capacity, heat tolerance, and energy allocation across ontogeny in the African clawed frog (Xenopus laevis), reared at six constant temperatures (17-32{degrees}C). We tested whether higher developmental temperatures generate trade-offs between accelerated growth and heat tolerance, and the consequences for post-metamorphic resilience to extreme heat. Rearing at 32{degrees}C was lethal before metamorphosis. At non-lethal warm temperatures (17-29{degrees}C), larvae and juveniles simultaneously accelerated development, maintained growth, and enhanced heat tolerance. However, juveniles reared at 29{degrees}C showed reduced survival, elevated corticosterone responses to acute stress, and diminished acclimation capacity, indicating increased energetic demands and constrained metabolic flexibility. These findings show that amphibians can integrate developmental plasticity with plastic adjustments in heat tolerance, but that such strategies incur cumulative physiological costs. By adopting an across-life-stage approach, our study highlights energy-allocation constraints that may limit population persistence under climate warming in species with complex life cycles.

ecology↗

bioRxiv2025

Effects of animal dormancy on oxidative stress, immune status, and glucocorticoids: a meta-analysis

Despite the growing interest of evolutionary biologists and ecologists in unravelling the mechanisms behind animal responses to challenging conditions, our knowledge remains limited. To contribute to this field, we conducted a global meta-analysis (N= 112 unique studies, k = 2,840 independent estimates) to synthesize empirical information on the influence of vertebrate dormancy (i.e., cold- and heat-induced dormancy) on redox status, immune function, and glucocorticoid levels. Our study reveals that dormancy has contrasting effects on animal physiology, depending on the thermoregulatory strategy. In endotherms, both dormant and arousal states are accompanied by reduced ROS production, lower oxidative damage, or upregulated antioxidant response, whereas in ectotherms, greater oxidative damage occurs only during the dormant state. Likewise, innate immune responses are upregulated during arousal in endotherms, while ectotherms downregulate pathways involved both in innate and adaptive responses during the dormant state. Interestingly, glucocorticoid levels remain stable throughout dormancy, suggesting that undergoing metabolic shifts may uncouple glucocorticoid release. These findings provide mechanistic explanation on the eco-evolutionary consequences of dormancy, revealing diverging strategies between endotherms and ectotherms. By highlighting metabolic depression as a central axis of these responses, our results also inform conservation strategies for dormant species facing rapid environmental change.

evolutionary biology↗

bioRxiv2025

Growth but not corticosterone, oxidative stress or telomere length is negatively affected by microplastic exposure in a filter-feeding amphibian

Microplastics (MPs) are of increasing global concern for species inhabiting aquatic habitats. However, the mechanisms behind animal responses to MPs need comprehensive exploration. Amphibians are the most threatened vertebrate group with most species having a complex life cycle, commonly with an aquatic larval stage. Here, we investigated whether exposure to an environmentally-relevant concentration of MPs affects the growth of filter-feeding larvae of the African clawed frog (Xenopus laevis), and the consequences for their stress physiology (corticosterone (CORT) levels), or health and ageing physiology (oxidative stress and telomere length). We conducted a 3x2 experiment with three levels of fibre exposure (fibres absent -control-, and MP and cellulose fibre treatments), and two stress levels (CORT absent -control-, and CORT present simulating a stressful condition). We observed a negative impact of MP exposure on larval growth; however, this did not alter the CORT levels, oxidative stress or telomere length. Our study shows that realistic concentrations of MPs is not enough to induce major alterations on the stress or health and ageing physiology of a filter-feeding amphibian. Whether compensatory growth responses during the post-metamorphic stages could lead to detrimental effects later in life should be explored in amphibians and other organisms with complex-life cycles.

evolutionary biology↗

bioRxiv2024

Ionizing radiation has negligible effects on the age, telomere length, and corticosterone levels of Chornobyl tree frogs

Pollutants, such as ionizing radiation, released at high levels by human activities can shape ecological and evolutionary processes. The accident occurred at Chornobyl nuclear power plant (Ukraine, April 1986) contaminated a large extension of territory after the deposition of radioactive material. Beyond the immediate negative impact caused by the accident, it is still under debate whether the chronic exposure to the radiation levels currently present in the area signifies a serious threat for organisms. One hypothesis suggests that current levels of radiation may cause unobservable damage in the short-term, but have long-term effects such as decreases in longevity. Here, we investigate through a field-based approach, whether current levels of radiation in Chornobyl negatively impact the age of a semi-aquatic vertebrate, the Eastern tree frog Hyla orientalis. We also explore whether radiation induces changes in an ageing marker, telomere length, or in the stress hormone corticosterone. We found no effect of total individual absorbed radiation (including both external and internal exposure) on frog age (n = 197 individuals sampled in three consecutive years). We also did not find any relationship between individual absorbed radiation and telomere length, but a negative relationship between individual absorbed radiation and corticosterone levels. Our results suggest that radiation levels currently experienced by tree frogs in Chornobyl may not be high enough to cause severe chronic damage to semi-aquatic vertebrates such as this species. This is the first study addressing age and stress hormones in Chornobyl wildlife, and thus future research will confirm if these results can be extended to other taxa.

ecology↗

bioRxiv2023

The impact of chemical pollution across major life transitions: a meta-analysis on oxidative stress in amphibians

Among human actions threatening biodiversity, the release of anthropogenic chemical pollutants -which have become ubiquitous in the environment- is a major concern. Chemical pollution can induce oxidative stress and damage by causing the overproduction of reactive oxygen species (ROS), and affecting the antioxidant system. In species undergoing metamorphosis ([~]80% of all extant animal species), antioxidant responses to chemical pollution may differ between pre- and post-metamorphic stages. Here, we meta-analysed (N = 86 studies, k = 2,012 estimates) the impact of chemical pollution on the redox balance across the three major amphibian life stages (embryo, larva, adult). Before metamorphosis, embryos and larvae activate their antioxidant pathways and do not show increased oxidative damage. In contrast, post-metamorphic individuals show unnoticeable antioxidant responses, and a marked oxidative damage in lipids. Also, type of pollutant (i.e., organic vs inorganic) promotes contrasting effects across amphibian life stages. Our findings show a divergent evolution of the redox balance in response to pollutants across life transitions of metamorphosing amphibians, likely linked to the characteristics of each life stage. Further comparative mechanistic approaches to wildlife responses to global changes will improve our understanding of these eco-evo-devo processes.

evolutionary biology↗

bioRxiv2022

Impact of ionizing radiation on the environmental microbiomes of Chernobyl wetlands

Radioactive contamination in the form of ionizing radiation can be a devastating pollutant because it has the potential to cause damage to DNA and other biomolecules. Anthropogenic sources of ionizing radiation include accidents in nuclear power plants, such as the one in Chernobyl 1986, which caused long-term radioactive pollution. Studies on animals within radioactive zones have provided us with a greater understanding of how wildlife can persevere despite chronic radiation exposure, however, we still know very little about the effects of radiation on the microbial communities in the environment. Here, we examined the impact of ionizing radiation and other environmental factors on the diversity and composition of environmental microbiomes in the wetlands of Chernobyl. We combined extensive field sampling along a gradient of radiation together with 16S rRNA high-throughput metabarcoding (Illumina NovaSeq). While radiation did not affect the alpha diversity of the microbiomes in sediment, soil, or water, it had a strong effect on the beta diversity, indicating that the microbial composition was affected by ionizing radiation. Specifically, we detected several microbial taxa that were more abundant in areas with high radiation levels within the Chernobyl Exclusion Zone, including bacteria and archaea known to be radioresistant. Overall, our results reveal the existence of rich and diverse microbiomes in Chernobyl wetlands, with multiple taxonomic groups that are able to thrive despite the radioactive contamination. Further field and laboratory-based approaches will help to forecast the functionality and re-naturalization dynamics of radiocontaminated environments.

ecology↗

bioRxiv2021

Assessment of exposure to ionizing radiation in Chernobyl tree frogs (Hyla orientalis)

Ionizing radiation can damage organic molecules, causing detrimental effects on human and wildlife health. The accident at the Chernobyl nuclear power plant (1986) represents the largest release of radioactive material to the environment. An accurate estimation of the current exposure to radiation in wildlife, often reduced to ambient dose rate assessments, is crucial to understand the long-term impact of radiation on living organisms. Here, we present an evaluation of the sources and variation of current exposure to radiation in breeding Eastern tree frogs (Hyla orientalis) males living in the Chernobyl Exclusion Zone. Total dose rates in H. orientalis were highly variable, although generally below widely used thresholds considered harmful for animal health. Internal exposure was the main source of absorbed dose rate (81% on average), with 90Sr being the main contributor (78% of total dose rate, on average). These results highlight the importance of assessing both internal and external exposure levels in order to perform a robust evaluation of the exposure to radiation in wildlife. Further studies incorporating life-history, ecological, and evolutionary traits are needed to fully evaluate the effects that these exposure levels can have in amphibians and other taxa inhabiting radio-contaminated environments.

ecology↗

bioRxiv2020

Unusual evolution of tree frog populations in the Chernobyl exclusion zone

Despite the ubiquity of pollutants in the environment, their long-term ecological consequences are not always clear and still poorly studied. This is the case concerning the radioactive contamination of the environment following the major nuclear accident at the Chernobyl nuclear power plant. Notwithstanding the implications of evolutionary processes on the population status, few studies concern the evolution of organisms chronically exposed to ionizing radiation in the Chernobyl exclusion zone. Here, we examined genetic markers for 19 populations of Eastern tree frog (Hyla orientalis) sampled in the Chernobyl region about thirty years after the nuclear power plant accident to investigate microevolutionary processes ongoing in local populations. Genetic diversity estimated from nuclear and mitochondrial markers showed an absence of genetic erosion and higher mitochondrial diversity in tree frogs from the Chernobyl exclusion zone compared to other European populations. Moreover, the study of haplotype network permitted us to decipher the presence of an independent recent evolutionary history of Chernobyl exclusion zones Eastern tree frogs caused by an elevated mutation rate compared to other European populations. By fitting to our data a model of haplotype network evolution, we suspected that Eastern tree frog populations in the Chernobyl exclusion zone have a high mitochondrial mutation rate and small effective population sizes. These data suggest that Eastern tree frogs populations might offset the impact of deleterious mutations because of their large clutch size, but also question the long term impact of ionizing radiation on the status of other species living in the Chernobyl exclusion zone.

ecology↗

bioRxiv2019

Telomere length covaries with age across an elevational gradient in a Mediterranean lizard

The timing of organisms senescence is developmentally programmed but also shaped by the interaction between environmental inputs and life-history traits. In ectotherms, ageing dynamics are still poorly understood despite their particularities concerning thermoregulation, regeneration capacity, or growth trajectory. Here, we investigate the role of life-history traits such as age, sex, body size, body condition, and tail autotomy (i.e self-amputation) in shaping telomere length of six populations of the Algerian sand lizard (Psammodromus algirus) distributed across an elevational gradient from 300 to 2500 meters above the sea level. Additionally, we show in a review table the available information on reptiles telomere length. We found that telomeres elongated with lizards age. We also observed that body size and age class showed a positive relationship, suggesting that cell replication did not shorten lizards telomeres by itself. Elevation affected telomere length in a non-linear way, a pattern that mirrored the variation in age structure across elevation. Telomere length was unaffected by tail autotomy, and was sex-independent, but positively correlated with body condition. Our results show that telomeres elongate throughout the first four years of lizards lifetime, a process that stress the role of telomerase in maintaining ectothermic telomeres, and, likely, in extending lifespan in organisms with indeterminate growth. Regarding the non-linear impact that elevation had on telomere length of lizards, our results suggest that habitat (mainly temperature) and organisms condition might play a key role in regulation ageing rate. Our findings emphasize the relevance of understanding species life histories (e.g. age and body condition) and habitat characteristics for fully disentangling the causes and consequences of lifespan trajectory.

ecology↗