Janek Boratyński | Polish Academy of Sciences (original) (raw)

Papers by Janek Boratyński

Oxidative stress (OS) and impaired immune function (IF) have been proposed as key physiological c... more Oxidative stress (OS) and impaired immune function (IF) have been proposed as key physiological costs of reproduction. The relationship between OS and IF remains unresolved, particularly in long-living iteroparous species. We studied physiological markers of maintenance (OS, IF markers) in lactating, post-lactating and non-lactating females of edible dormice-a long-living rodent. We predicted the OS balance and IF to be compromised by lactation, especially in older females expected to face stronger trade-offs between life functions. We found that the age predictor (body size) correlated negatively with white blood cell level (WBC), positively with neutrophils to lymphocytes ratio and had no effect on OS markers. Oxidative damage markers (reactive oxygen metabolites (ROMs); but not antioxidant capacity) and body size-adjusted WBC were the lowest in lactating, higher in post-lactating and the highest in nonlactating females. Body size/age did not affect this correlation suggesting a similar age-independent allocation strategy during reproduction in this species. The path analysis testing the causal relationship between ROMs and WBC revealed that IF is more likely to affect OS than vice versa. Our study indicates the trade-off between crucial life functions during reproduction and suggests that immunosuppression reduces the risk of OS; therefore, mitigating oxidative costs of reproduction.

Frontiers in Ecology and Evolution, 2024

Heterothermy is considered to be the most effective energy-saving strategy improving survival und... more Heterothermy is considered to be the most effective energy-saving strategy improving survival under natural conditions. Interspecific studies suggest that this strategy is also associated with reduced reproductive output. Yet little is known about the reproductive consequences of heterothermy use at the intraspecific level and thus its repercussions for microevolutionary processes. Moreover, as yet no study has aimed to test if litter size and juvenile mass are affected by torpor use in wild captured animals under undemanding laboratory conditions. Here we tested the hypothesis that intraspecific variation in heterothermy use is associated with different reproductive successes, being the result of the evolution of distinct life histories. We predicted that heterothermy use in winter negatively correlates with litter size and juvenile body mass during the subsequent breeding season. To test this prediction, we used yellow-necked mice from a population in which individuals consistently differ in their use of heterothermy in winter. We measured body size (head width) and body mass, basal metabolic rate, as well as metabolism and body temperature during fastinginduced torpor in wild caught mice in winter. Phenotyped mice were bred in the subsequent summer selectivelymales and females with similar heterothermy characteristics were paired, the most to the least heterothermic. Dam body size, but not basal metabolism, was positively correlated with litter size (but not juvenile mass). However, when accounting for this relationship, litter size was negatively while juvenile mass was positively correlated with the average heterothermy use of a given couple. Our study indicates that heterothermy use correlates with specific life-history strategies arising from a fundamental evolutionary trade-off between survival and reproduction.

The Journal of Experimental Biology

In many mammalian species, variation in body temperature (Tb) exceeds the values suitable for def... more In many mammalian species, variation in body temperature (Tb) exceeds the values suitable for defining homeothermy, making it justifiable and even necessary to resort to the term “heterothermic”. However, Tb data are only available for ca. 1% of extant mammalian species. We investigated variations in Tb in wild free-living and experimentally food-deprived yellow-necked mice Apodemus flavicollis, during the temperate-zone autumn-winter period. In line with the adaptive framework for endothermic thermoregulation, we hypothesised that Tb in the mice should be adjustable with the energetic cost-benefit trade-off associated with maintaining homeothermy. In laboratory conditions, mice clearly entered a state of daily torpor when food-deprived. Our study thus makes it clear that A. flavicollis is a heterothermic species in which food deprivation results in switching between endothermic and poikilothermic thermoregulation. We also assumed that, in free-living mice, heterothermy increases wi...

Forest Ecology and Management, 2020

Abstract Many forest dwelling species faces increasing shortage of natural shelters as tree cavit... more Abstract Many forest dwelling species faces increasing shortage of natural shelters as tree cavities due to a decline of the abundance of large, old trees, eliminated from the forest stands by silviculture. Formation of monocultures, changes in species and age composition of forest stands significantly reduce abundance of such daily roosts, crucial for fitness of many vertebrates. That is why using of substitutes of natural shelters like nest-boxes as a habitat restoration tool increased in last decades. Despite many studies investigating species preferences affecting utilization of nest-boxes, there are almost none comparing natural and artificial-roosts selection at one study site. That is why in our study by using radio-tracking method we investigated the usage of natural and artificial shelters by arboreal rodent - edible dormouse Glis glis in commercial pine forest. Our results show that significant proportion (~50–70%) of utilized roosts were of natural origin, even though artificial shelters were available. Roosts were mostly found in deciduous trees, as birches and oaks, which dormice chose accordingly to the abundance on the study plot. Significantly low selection ratios were found for the most common species on the study plot - Scots pine Pinus sylvestris, probably due to silviculture practices, that for economical reasons promote healthy trees through multiple practices. We also found that the vicinity of roosting sites was characterised by dense vegetation of young deciduous trees. Our study indicates that preservation of the mixed forest stands with dense understory layer and old deciduous trees is crucial for arboreal rodents for roosting behavior in managed forests. Moreover, we suggest that maintaining a higher number of tree species that are not managed by foresters (as birch) can improve the functioning of the populations of arboreal rodents more effectively than installing artificial shelters.

Ecology and Evolution

For the last two decades, behavioral physiologists aimed to explain a plausible covariation betwe... more For the last two decades, behavioral physiologists aimed to explain a plausible covariation between energetics and personality, predicted by the “pace‐of‐life syndrome” (POLS) hypothesis. However, the results of these attempts are mixed with no definitive answer as to which of the two most acknowledged models “performance” or “allocation” predicts covariation between consistent among‐individual variation in metabolism and repeatable behavior (animal personality). The general conclusion is that the association between personality and energetics is rather context‐dependent. Life‐history, behavior, and physiology as well as its plausible covariation can be considered a part of sexual dimorphism. However, up to now, only a few studies demonstrated a sex‐specific correlation between metabolism and personality. Therefore, we tested the relationships between physiological and personality traits in a single population of yellow‐necked mice Apodemus flavicollis in the context of a plausible ...

Mammal Research

Metabolic physiology and animal personality are often considered linked to each other, shaping ec... more 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 ...

Metabolic physiology and animal behaviour are often considered to be linked, positively or negati... more Metabolic physiology and animal behaviour are often considered to be linked, positively or negatively, according to either the performance or allocation models. Performance seems to predominate over allocation in natural systems, but the constraining environmental context may reveal allocation limitations to energetically expensive behaviours. Habitat disturbance, such as the large-scale fire that burnt wetlands of Biebrza National Park (NE Poland), degrades natural ecosystems. It arguably reduces food and shelter availability, modifies predator-prey interactions, and poses a direct threat for animal survival, such as that of the wetland specialist root vole Microtus oeconomus. We hypothesized that fire disturbance induces physiology-behaviour co-expression, as a consequence of changed environmental context. We repeatedly measured maintenance and exercise metabolism, and behavioural responses to the open field, in a root voles from post-fire and unburnt locations. Highly repeatable maintenance metabolism and distance moved during behavioural tests correlated positively, but relatively labile exercise metabolism did not covary with behaviour. At the same time, voles from a post-fire habitat had higher maintenance metabolism and moved shorter distances than voles from unburnt areas. We conclude there is a prevalence of the performance mechanism, but simultaneous manifestation of context-dependent allocation constraints of the physiology-behaviour covariation after disturbance. The last occurs at the within-individual level, indicating the significance of behavioural plasticity in the context of environmental disturbance.

Current Zoology, 2020

Small mammals that are specialists in homeothermic thermoregulation reduce their self-maintenance... more Small mammals that are specialists in homeothermic thermoregulation reduce their self-maintenance costs of normothermy to survive the winter. By contrast, heterothermic ones that are considered generalists in thermoregulation can lower energy expenditure by entering torpor. It is well known that different species vary the use of their strategies to cope with harsh winters in temperate zones; however, little is still known about the intraspecific variation within populations and the associated external and internal factors. We hypothesized that yellow-necked mice Apodemus flavicollis decrease their resting metabolic rate (RMR) from autumn to winter, and then increase it during spring. However, since the alternative for seasonal reduction of RMR could be the development of heterothermy, we also considered the use of this strategy. We measured body mass (mb), RMR, and body temperature (Tb) of mice during 2 consecutive years. In the 1st year, mice decreased whole animal RMR in winter, b...

The repeatable among-individual variation in behavior (animal personality) is considered to affec... more The repeatable among-individual variation in behavior (animal personality) is considered to affect fitness. The variation in personality traits is shaped by complex evolutionary mechanisms involving energy allocation and resource acquisition. However, an association between personality and individual performance in energy gain in the natural environment still seems underexplored. The aim of our study was to test a hypothesis that consistent individual variation in behavior affects the energy acquisition of unpredictable food resources. We predicted that more explorative individuals would be finding ephemeral food resources with higher probability than those less explorative. The quasi-experiment with 'random-walkingfeeders' was performed to assess the use of unpredictable food resources in the natural habitat occupied by free-ranging arboreal rodents-edible dormice Glis glis. A repeated open field test at laboratory conditions was conducted to assess whether male dormice show consistent among-individual variation in behavior. The open field test analysis indicated two main components of dormice behavior: exploration and boldness, from which only the first one was repeatable and thus considered as a component of animal personality. The probability of finding a feeder increased with exploration, independently of dormice age and body size. The results indicate that exploration can be considered an adaptive trait that improves energy acquisition. We suggest that the behavioral among-individual variation within populations persists due to the usage of distinct foraging strategies in the face of fluctuations in food resources availability.

The Journal of Experimental Biology, 2017

According to theoretical predictions endothermic homeotherms can be classified as either thermal ... more According to theoretical predictions endothermic homeotherms can be classified as either thermal specialists and thermal generalists. In high cost environments thermal specialists are supposed to be more prone to use facultative heterothermy than generalists. We tested this hypothesis on the intraspecific level using laboratory male mice (C57BL/cmdb) fasted under different thermal conditions (20 and 10°C), and for different time periods (12-48 h). We predicted that variability of body temperature (Tb) and time spent with Tb below normothermy increase with the increase of environmental demands (duration of fasting and cold). To verify the above prediction, we measured Tb and energy expenditure of fasted mice. We did not record torpor bouts but we found that variations in Tb and time spent in hypothermia increased with environmental demands. In response to fasting, mice also decreased their energy expenditure. Moreover, we found that animals that showed more precise thermoregulation w...

The Journal of experimental biology, Jan 12, 2017

The duration of melatonin (MEL) secretion conveys information about day length and initiates a ca... more The duration of melatonin (MEL) secretion conveys information about day length and initiates a cascade of seasonal phenotypic adjustments in photoresponsive mammals. With shortening days they cease reproduction, minimize energy expenditure, enhance thermoregulatory capacity and adjust functioning of the hypothalamic-pituitary-adrenal (HPA) axis to match the winter increase in energy demands. Within each season stress plays an important role in the flexible adjustments of a phenotype to environmental perturbations. Recent studies showed that thermal reaction norms of energy metabolism were narrower in winter-acclimated Siberian hamsters, Phodopus sungorus We tested the hypothesis that physiological changes occurring in response to prolonged MEL signal, including changes in secretion of stress hormones, are responsible for the seasonal decrease in phenotypic flexibility of energy metabolism in photoresponsive mammals. To quantify reaction norms for basal metabolic rate (BMR) and corti...

Physiological and biochemical zoology : PBZ

Basal metabolic rate (BMR) correlates with the cost of life in endothermic animals. It usually di... more Basal metabolic rate (BMR) correlates with the cost of life in endothermic animals. It usually differs consistently among individuals in a population, but it may be adjusted in response to predictable or unpredictable changes in the environment. The phenotypic flexibility of BMR is considered an adaptation to living in a stochastic environment; however, whether it is also repeatable it is still unexplored. Assuming that variations in phenotypic flexibility are evolutionarily important, we hypothesized that they are consistently different among individuals. We predicted that not only BMR but also its flexibility in response to changes in ambient temperature (Ta) are repeatable on short- and long-term timescales. To examine this, we acclimated Siberian hamsters (Phodopus sungorus) for 100 d to winterlike and then to summerlike conditions, and after each acclimation we exposed them interchangeably to 10° and 28°C for 14 d. The difference in BMR measured after each exposure defined an i...

Acta Chiropterologica, 2012

BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting... more BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.

Journal of Comparative Physiology B, 2016

periods as a measure of the scope of phenotypic flexibility. After winter acclimation, hamsters w... more periods as a measure of the scope of phenotypic flexibility. After winter acclimation, hamsters were lighter, had lower whole animal BMR, higher fNST than in summer, and developed heterothermy. After these short acclimations to the above-mentioned temperatures, hamsters showed reversible changes in BMR and fNST; however, these traits were less flexible in winter than in summer. We conclude that seasonal acclimation affects hamster responses to intraseasonal variations in the thermal environment. We argue that understanding seasonal changes in phenotypic flexibility is crucial for predicting the biological consequences of global climate changes.

Journal of Experimental Biology, 2019

Theoretical modelling predicts that the thermoregulatory strategies of endothermic animals range ... more Theoretical modelling predicts that the thermoregulatory strategies of endothermic animals range from those represented by thermal generalists to those characteristic for thermal specialists. While the generalists tolerate wide variations in body temperature (Tb), the specialists maintain Tb at a more constant level. The model has gained support from inter-specific comparisons relating to species and population levels. However, little is known about consistent among-individual variation within populations that could be shaped by natural selection. We studied the consistency of individual heterothermic responses to environmental challenges in a single population of yellow-necked mice (Apodemus flavicollis), by verifying the hypothesis that Tb variation is a repeatable trait. To induce the heterothermic response, the same individuals were repeatedly food deprived for 24 h. We measured Tb with implanted miniaturised data loggers. Before each fasting experiment, we measured basal metabo...