Conservation Physiology最新文献

To limit the impact of invasive predator species on the ecosystem of Floreana Island, Galapagos, a large-scale rodent eradication program was implemented. Due to the significant risk of secondary exposure to rodenticide, a mitigation tactic was used to protect the only native raptor found on Floreana, the Galapagos short-eared owl (Asio flammeus galapagoensis). A large proportion of the owl population was brought into human care in July 2023 with the goal to release back to the wild following the completion of the eradication program and reduction of the risk of exposure to rodenticides. During this time under human care, health examinations including blood collection for assessment of haematology and biochemistry parameters were completed. Descriptions of leukocyte morphology and population-based reference intervals (RI) are reported here utilizing results from 62 clinically healthy adults. Sex was determined using polymerase chain reaction, allowing for comparisons between males (n = 29) and females (n = 33). Statistically significant differences were found for several parameters: packed cell volume, relative and absolute monocyte counts, total protein, calcium and phosphorus levels were higher in females, while uric acid and glucose levels were significantly higher in males. These baseline RI are an important tool for assessment of this unique population while under human care, and will allow for comparisons and continued health monitoring after release back to the island of Floreana.

The analysis of DNA methylation data for wildlife conservation is gaining momentum as the technology for quantifying the methylome becomes mainstream. The use of epigenetic information extracted from tissue samples can be used for estimating chronological age, individual traits and phenotypic variation. Methylation data present an exciting opportunity to study wildlife populations, with the potential to provide insights into age structure, vital rates and health. However, the statistical methodology for answering the emerging research questions has been developed and mostly applied in the human biomedical setting. We review the key methodologies commonly used in wildlife settings, and methods that have been used only in human studies so far that could improve our understanding of wildlife epigenomic changes. We show how the different methods relate to each other and how they link to research questions, illustrating each approach with data from a case study, a large dataset from wild bottlenose dolphins (Tursiops spp.) from the US southeast and Gulf coast. Estimating chronological age from models called epigenetic clocks and understanding the relationship between epigenetic indicators of health and exposure to stressors are both key goals in wildlife settings; however, we show that a single model cannot do both accurately. This is a fundamental limitation of clock-type models and might explain why some age-related health conditions have been found to be related to epigenetic age and others not. Decoupling the analysis of age and health is challenging because the two are confounded but is especially important in wildlife settings where age prediction is often the main analytical objective.

Understanding how animals respond to environmental stressors across their life cycle is essential for predicting species' vulnerability to climate change. Here, we systematically reviewed the literature to quantify the variation in research effort on different life stages in the field of conservation physiology. Specifically, we reviewed experimental studies measuring physiological and life-history responses to climatic stressors across three representative scientific journals: Conservation Physiology, Journal of Thermal Biology and Journal of Experimental Biology. Our systematic map of 1276 studies revealed a pronounced underrepresentation of studies on embryos, representing only 8% to 9% of studies. This pattern was remarkably consistent across all axes considered (i.e. journals, taxonomic groups, physiological traits and environmental stressors). We also found that 80% of studies only investigated single life stages, and over 5% of studies did not clearly report the life stage(s) used. Despite the increasing recognition of the ecological importance and sensitivity of early life stages to environmental stressors, we found no evidence that research on embryos has gained traction over the past decade (2013-2024). We argue that these ontogenetic biases likely reflect a combination of historical precedents and enduring methodological and logistical constraints that continue to shape research agendas. To build a more holistic understanding across the life cycle, we: (i) call for a paradigm shift placing embryos at the center of experimental agendas, (ii) outline emerging methodological advances that increase the feasibility of research on early life stages, (iii) demonstrate how studies on embryos align with ethical considerations for animal research, (iv) highlight perspectives for future evidence syntheses and study reporting and (v) promote investigations of the mechanisms underlying physiological variation across ontogeny. Closing the ontogenetic gap will be key to improving our ability to predict population-level impacts of climate change and guiding more effective conservation and management interventions.

[This corrects the article DOI: 10.1093/conphys/coaf033.].

Groundwater systems of the Yucatan Peninsula form one of the world's most intricate aquifer systems, supporting a unique and ecologically essential subterranean fauna. The physiological capacities of resident species, and their tolerance or ability to cope with changing environmental challenges is unknown for most species. Considering the vertical stratification of anchialine ecosystems, accelerated climate change and anthropogenic pressures, we sought to investigate the physiological characteristics of a key groundwater-restricted species (stygobionts) that is broadly distributed in the Yucatan Peninsula and has been observed in fresh- and marine groundwater. Thus, we (i) characterized the respiratory metabolism, osmoregulatory capacity and thermal tolerance of the cave isopod Creaseriella anops and (ii) evaluated how variations in salinity and oxygen concentration impact its physiological performance and antioxidant defence system. Our findings indicate that C. anops is isosmotic at 17.7‰ (580.8 mOsm/kg) and possesses a strong osmoregulatory capacity. When acclimated to freshwater (0‰) at 26 ± 1°C, C. anops demonstrated a maximum critical temperature of 33.6 ± 1.3°C and a minimum critical temperature of 19.0 ± 2.0°C, with an aerobic scope of 0.053 mg O₂/g/h. Dissolved oxygen levels (15 to 100% saturation) did not influence routine oxygen consumption rates. Acute shifts in salinity (from 0‰ to 8, 14 or 35‰) initially elevated oxygen consumption rates, which returned to routine levels within three hours across all salinity conditions. This metabolic response was associated with a slight activity increase in antioxidant enzymes and elevated protein carbonylation and lipid peroxidation. In summary, C. anops showed outstanding osmoregulatory, metabolic and antioxidant capacities that likely contribute to its wide distribution within the YP's anchialine ecosystems, providing insights into how this species may respond to future environmental shifts.

Asian elephants, an iconic flagship species, are increasingly exposed to seasonal pollution and ambient fine particulate matter (PM_2.5) due to land burning and regional air pollution across Northern Thailand. Unlike humans and domesticated animals, captive elephants often spend prolonged periods outdoors with minimal air quality or mitigation measures, yet the physiological consequences of chronic PM_2.5 exposure remain poorly understood. This study investigated how daily PM_2.5 levels affected oxidative stress and physiological stress biomarkers in Asian elephants involved in tourist activities in Thailand. A total of 27 elephants from seven tourist facilities in Northern Thailand were repeatedly sampled for serum 8-hydroxy-deoxyguanosine (8-OHdG, a marker of oxidative DNA damage), serum malondialdehyde (MDA, a marker of lipid peroxidation) and faecal glucocorticoid metabolites (fGCM, a marker of stress). Daily PM_2.5 concentrations were classified into tertiles (low, moderate, high). Linear mixed-effects models were used to test associations between PM_2.5 and each biomarker, with elephant ID and camp as random intercepts. Elephants exposed to high PM_2.5 showed approximately 40% higher DNA damage and 35% higher stress hormone concentrations compared to low PM_2.5 conditions. In contrast, lipid peroxidation concentrations were about 15% lower under high PM_2.5 conditions, suggesting possible compensatory antioxidant responses. The strongest changes occurred when pollution increased from low to moderate levels, further increases produced smaller effects. These findings suggest that seasonal air pollution elevates stress hormones and triggers complex, at times counterintuitive, changes in oxidative biomarkers, likely due to physiological buffering in elephants, with potential health implications. Integrated multi-biomarker panels are therefore essential for accurately monitoring air quality impacts on captive megafauna. Proactive management should prioritize reducing exposure and providing nutritional support during peak pollution conditions to mitigate cumulative stress.

[This corrects the article DOI: 10.1093/conphys/coaf027.].

Dehydroepiandrosterone (DHEA) is an important hormone precursor for androgen and oestrogen sex steroids, yet it is understudied in wildlife and has not been measured in rhinoceroses. The objective of this study was to examine serum DHEA concentrations in ex situ black (Diceros bicornis; n = 22 male, 18 female) and white (Ceratotherium simum; n = 25 male, 46 female) rhinoceroses. A commercially available DHEA immunoassay was validated for use with rhino serum, and monthly samples (n = 1029) were analysed. Analytical validation included demonstrating parallel displacement curves between serially diluted standards and pooled extracts, as well as 91% extraction efficiency in a spike and recovery test. Differences in DHEA concentrations relative to species, age, sex and pregnancy status were analysed using linear mixed models. Serum DHEA concentrations were higher (P < 0.001) in black (194 ± 14.2 pg/ml) versus white (123 ± 8.0 pg/ml) rhinoceroses and demonstrated a non-linear relationship with age in both species, with concentrations peaking around 15 years of age before declining thereafter. No sex differences between males and non-pregnant females were detected in either rhinoceros species. White rhinoceros DHEA concentrations were higher (P < 0.001) in pregnant (309 ± 31.9 pg/ml, n = 15) compared to non-pregnant (120 ± 10.4 pg/ml, n = 41) females; pregnant black rhinoceroses similarly produced elevated DHEA concentrations during pregnancy (1092 ± 90.3 pg/ml; n = 2) compared to non-pregnant (229 ± 8.1 pg/ml; n = 17) females. DHEA concentrations also increased throughout gestation particularly during mid- to late gestation in both species. These findings provide new insight into rhinoceros endocrinology and suggest potential utility of DHEA for monitoring pregnancy status.

Fishing is one of the most sustained forms of human-wildlife interaction and can alter trait distributions through selective harvest and repeated disturbance. Such changes, whether plastic or evolutionary, may alter productivity, resilience, and recovery in exploited species. The sand flathead (Platycephalus bassensis), a benthic ambush predator with strong site fidelity, supports lutruwita (Tasmania's) largest recreational fishery and is exposed to contrasting levels of fishing pressure across its range. In southern Tasmania, fishing mortality exceeds natural mortality more than fivefold and biomass has fallen below 20% of unfished levels, while northern regions remain comparatively lightly fished. This regional contrast offers a natural setting in which to investigate whether sustained harvest is associated with regional differences in physiology and behaviour, and whether such variation is more consistent with fishing pressure, environmental conditions, or their interaction. We compared mass-specific metabolic rate, boldness, and size-at-age between sand flathead from heavily and lightly fished regions. Metabolic rate was measured using intermittent flow-through respirometry, and boldness was quantified in a shuttlebox based on exploration latency and bait strikes. Fish from the heavily fished south exhibited smaller size-at-age, a 62% higher mean metabolic rate, and a transient post-capture elevated metabolic rate consistent with greater metabolic reactivity or stress responsiveness, whereas boldness did not differ between regions. Our findings align with other exploited systems and raise the possibility that trait diversity of sand flathead in southern regions of Tasmania have been shaped, at least in part, by fisheries selection. We discuss the relevance of these results for fisheries management and emphasize the importance of assessing trait variation in wild populations, where expression is likely shaped by the interactive effects of fishing pressure and local ecological conditions.

[This corrects the article DOI: 10.1093/conphys/coaf003.].