Boratynski, Z. | bioRxiv Science

bioRxiv2024

Covariation between metabolic and radioactive dose rates in Chornobyl rodents

High metabolic rate may provide fitness benefits for individuals. But high metabolic rates incur energetic costs and the need to ingest more food, increasing the risks of ingesting harmful substances from the environment. How organisms respond to elevated levels of ionizing radiation is an important question in the light of increasing pollution from nuclear accidents and waste, as well as ever-increasing reliance on radiation in medical diagnostics and therapies. We investigated how limits to metabolic rate, and aerobic metabolic scope (ceiling of energetic activity above maintenance levels), of wild rodents inhabiting a gradient of radioactive contamination from the Chernobyl accident covary with the biological burden of radionuclides in their bodies. Our results demonstrate that high biological dose rate correlates with high self-maintenance and low aerobic capacity in adults. In contrast, in subadults high dose rate correlates with high aerobic capacity. Consequently, high dose rate correlates with low aerobic scope in adults, but with high aerobic scope in subadults. Despite the uncertainty of the causal mechanisms, whether the dose rate affects the metabolic rate, the reverse or the reciprocal feedback prevail, it can be hypothesized that metabolic down-regulation could contribute to protection against radioactive exposure. Yet, metabolic down-regulation might be constrained by developmental obligations. Understanding the physiological mechanisms affecting responses to radiation exposure is key for risk assessment of environmental contamination, radiotherapies, and space exploration, and may help to rectify discordant opinions concerning the effects of radiation on the ecology of organisms living in Chornobyl.

ecology↗

bioRxiv2023

Performance and allocation can simultaneously shape behaviour in fire-disturbed populations of root vole

Metabolic physiology and animal personality are often considered linked to each other, shaping ecological and evolutionary strategies along a life-history continuum. The energy allocation model predicts a negative while the performance model predicts a positive correlation between the rate of metabolic processes and behaviours, such as activity level. The models might operate simultaneously but depending on the context one can predominate over the other, determining expression of alternative pro- and reactive behavioural strategies. Large-scale fires, such as the one that burnt wetlands of Biebrza National Park (NE Poland), degrade natural habitats, affect amount of food and shelters and modify predatory-prey interactions. Fires pose also direct threat to survival of local populations, such as the wetland specialist root vole (Microtus oeconomus). We hypothesized that fire disturbance, by changing environmental context and selective regimes, determines mechanisms linking physiology and behaviour. Positive relation found among most studies, predicted by the performance model, would revert to negative relation, predicted by the allocation model, affecting animals ecological strategy in disturbed habitat. We repeatedly measured maintenance and exercise metabolic rates and activity behaviour on voles from post-fire and unburnt populations. Repeatable maintenance metabolism and activity level were positively correlated, but more labile exercise metabolism did not explain behaviour. The correlations were not strongly affected by fire disturbance, but voles from post-fire habitat had higher maintenance but not maximum metabolism and moved shorter distances than individuals from unburnt area. The results suggest that performance model predominates, while habitat disturbance might reveal some allocation constraints on physiology-personality linkage. Summary statementContrasting allocation and performance models, for energetics-behaviour linkage, were tested in context of fire-disturbance. Positive (performance) correlation predominated but animals from burned habitat had elevated metabolism and suppressed exploration (allocation).

zoology↗