Lumír Gvoždík

Institute of Vertebrate Biology · Research Facility 'Studenec'

The term ‘thermal niche’ is frequently used in ecology. Using the Web of Science database, I reviewed how the term has been used in current literature (2000–2015). While the use of ‘thermal niche’ has increased notably over the last 15 years, its meaning differs between studies. Only 10% of studies measured thermal niche directly as the range of bo...

Many ectotherms modify their phenotype seasonally as a response to variation in abiotic factors. Given the potential of seasonal acclimation to reduce the impact of climate change on the dynamics of ectotherm populations, the adaptive evolution of this reversible plasticity has received much attention. Nevertheless, the key assumption of selection...

Temperature is an important factor determining distribution and abundance of organisms. Predicting the impact of warming climate on ectotherm populations requires information about species’ thermal requirements, so-called ‘thermal niche’. The characterization of thermal niche remains a complicated task. We compared the applicability of two indirect...

Many animals rely on their escape performance during predator encounters. Because of its dependence on body size and temperature, escape velocity is fully characterized by three measures, absolute value, size-corrected value, and its response to temperature (thermal sensitivity). The primary target of the selection imposed by predators is poorly un...

Many ectothermic species use behavioural thermoregulation to reduce their exposure to climate change. The buffering effect of behavioural thermoregulation will depend on the time available for an ectotherm to attain a body temperature within the target range, that is, the ‘opportunity for thermoregulation’. Behavioural thermoregulation can be furth...

Ectothermic organisms respond to rapid environmental change through a combination of behavioral and physiological adjustments. As behavioral and physiological traits are often functionally linked, an effective ectotherm response to environmental perturbation will depend on the direction and magnitude of their association. The role of various modifi...

Body‐size dependence of metabolic rate, body surface and scale morphology complicate disentangling the contribution of these characteristics to adaptive changes in total evaporative water loss (TEWL) of reptiles. To separate adaptive changes from size‐related dependence, we compared intra‐ and interspecific scaling of several candidate traits in ey...

Tonic immobility (TI) is an important antipredator response employed by prey in the last stages of a predation sequence. Evolution by natural selection assumes consistent individual variation (repeatability) in this trait. In ectotherms, which experience variable body temperatures, TI should be repeatable over a thermal gradient to be targeted by n...

Resting metabolic rate (RMR), i.e. spent energy necessary to maintain basic life functions, is a basic component of energy budget in ectotherms. The evolution of RMR through natural selection rests on the premise of its non-zero repeatability and heritability, i.e. consistent variation within individual lifetimes and resemblance between parents and...

Predation is a key ecological interaction affecting populations and communities. Climate warming can modify this interaction both directly by the kinetic effects of temperature on biological rates and indirectly through integrated behavioural and physiological responses of the predators and prey. Temperature dependence of predation rates can furthe...

The relationship between the minimum metabolic requirements (standard metabolic rate, SMR) and energy costs of non-mandatory physiological functions and behaviour is fundamental for understanding species responses to changing environmental conditions. Theory predicts that ectotherms manage their energy budget depending on whether the relationship b...

Sound production is a widespread phenomenon among animals. Effective sound use for mate or species recognition requires some acoustic differentiation at an individual or species level. Several species of caudate amphibians produce underwater sounds, but information about intra-and interspecific variation in their acoustic production is missing. We...

Locomotor activity is a major attribute of animals. Although this trait determines important ecological processes, such as dispersal and species interactions, the sources of its variation are not fully understood. We examined the influence of body temperature (13, 18, 23, and 28°C) and individual identity on spontaneous locomotor activity in juveni...

The coexistence of ectothermic species is enabled among other factors by the differentiation of their thermal niches. While this phenomenon is well described from deep temperate lakes, it is unclear whether the same pattern applies to temporary pools. In this study, we examined fundamental thermal niches in three coexisting annual killifish species...

Many ectotherms reduce their exposure to changing thermal conditions using behavioral thermoregulation. The effectiveness of behavioral thermoregulation in maintaining ectotherm body temperatures within the target range is influenced not only by environmental (operative) temperatures but also by the presence of other con- and heterospecific individ...

Coexistence of species with similar requirements is allowed, among others, through trade‐offs between competitive ability and other ecological traits. Although interspecific competition is based on two mechanisms, exploitation of resources and physical interference, trade‐off studies largely consider only species’ ability to exploit resources. Usin...

The energy costs of self-maintenance (standard metabolic rate, SMR) vary substantially among individuals within a population. Despite the importance of SMR for understanding life history strategies, ecological sources of SMR variation remain only partially understood. Stress-mediated increases in SMR are common in subordinate individuals within a p...

Tail autotomy is a crucial antipredatory lizard response, which greatly increases individual survival, but at the same time also compromises locomotor performance, sacrifices energy stores and induces a higher burden due to the ensuing response of regenerating the lost body part. The potential costs of tail autotomy include shifts in energy allocat...

Distribution and abundance of temperate ectotherms is determined, in part, by the depletion of their limited caloric reserves during wintering. The magnitude of winter energy drain depends on the species-specific capacity to seasonally modify the minimal maintenance costs. We examined seasonal variation of minimum oxygen consumption between two new...

Measuring standard metabolic rates in newts remains a complicated task despite substantial methodological and technological advances in the field. We examined the influence of aquatic versus terrestrial conditions in respirometry chambers on measurements of respiratory gases and motor activity in alpine newts, Ichthyosaura alpestris, during their a...

Many ectotherms effectively reduce their exposure to low or high environmental temperatures using behavioral thermoregulation. In terrestrial ectotherms, thermoregulatory strategies range from accurate thermoregulation to thermoconformity according to the costs and limits of thermoregulation, while in aquatic taxa the quantification of behavioral t...

A continuing issue in evolutionary thermal biology is the mismatch between preferred body temperatures (Tpref) and optimal temperatures (Topt) for whole-animal performance. Using phylogenetic comparative analyses, I examined the hypothesis that a difference in the rates at which Tpref and Topt evolve causes the mismatch in a lineage of European new...

Metabolic rates vary consistently among individuals within a population, providing raw material for natural selection. Although individual energy demands may play an increasingly important role for ectotherm survival under warmer and more variable winter conditions, whether individual variation in metabolic rates persists during overwintering is vi...

Many organisms seasonally modify their standard metabolic rates (SMR). However, the diversity of cues triggering the acclimatization response remains little understood. We examined the influence of experimentally induced aquatic‐to‐terrestrial habitat shift on the thermal sensitivity of SMR in newts. Standard metabolic rates increased with temperat...

Ectotherms compensate for variation in thermal environments in diverse behavioural ways. Despite widely occurring sex differences in morphology and physiology, the sex-specific thermal sensitivity of behavioural traits has received little attention. We tested the interactive influence of sex and environmental temperature on predator-induced respons...

Thermal quality and predation risk are considered important factors influencing habitat patch use in ectothermic prey. However, how the predator's food requirement and the prey's necessity to avoid predation interact with their respective thermoregulatory strategies remains poorly understood. The recently developed 'thermal game model' predicts tha...

Heterospecific hybrids often suffer from a lowered fitness relative to parental species. Contextdependent intrinsic costs of hybridization are partially due to a malfunction in cell biochemical machinery that affects metabolic rates at the organismal level. This study examines whether heterospecific hybridization influences the metabolic costs of m...

Many organisms respond to the heterogeneity of abiotic environmental conditions by plastic modifications of their phenotypes (acclimation or acclimatization). Despite considerable research efforts in this area, the beneficial (adaptive) effect of acclimation or acclimatization is still debated. We examined whether the development of newt larvae (Ic...

Many ectotherms possess the ability to behaviourally regulate their body temperatures. Thermoregulatory behaviour is affected by various biotic and abiotic factors, which may cause a substantial bias in the laboratory estimates of preferred body temperatures (T p). We examined thermoregulatory behaviour in alpine newts, Ichthyosaura (formerly Tritu...

The ability to modify phenotypes in response to heterogeneity of the thermal environment represents an important component of an ectotherm’s non-genetic adaptive capacity. Despite considerable attention being dedicated to the study of thermally-induced developmental plasticity, whether or not interspecific interactions shape the plastic response in...

Thermoregulatory behaviour represents an important component of ectotherm non-genetic adaptive capacity that mitigates the impact of ongoing climate change. The buffering role of behavioural thermoregulation has been attributed solely to the ability to maintain near optimal body temperature for sufficiently extended periods under altered thermal co...

The maternal manipulation hypothesis states that ectothermic females modify thermal conditions during embryonic development to benefit their offspring (anticipatory maternal effect). However, the recent theory suggests that the ultimate currency of an adaptive maternal effect is female fitness that can be maximized also by decreasing mean fitness o...

Seasonal acclimation and thermoregulation represent major components of complex thermal strategies by which ectotherms cope with the heterogeneity of their thermal environment. Some ectotherms possess the acclimatory capacity to shift seasonally their thermoregulatory behavior, but the frequent use of constant acclimation temperatures during experi...

Behavioural regulation of body temperature in thermally heterogeneous habitats requires different amounts of time that could otherwise be dedicated to foraging and social activities. In this study I examined how four populations of the lizard Zootoca vivipara along an altitudinal gradient (250-1450 m) adjust their thermal-physiology traits and ther...

1. Many organisms respond to seasonal temperature fluctuations by the reversible modification of whole‐animal performance. Semiaquatic ectotherms, which possess this acclimatory capacity in swimming speed, lack the plastic response in terrestrial locomotor performance and vice versa. Theory predicts that the presence of reversible (seasonal) therma...

Oviposition-site choice has profound fitness consequences for both a mother and her offspring. The adaptive significance of oviposition behaviour for both generations depends on two rarely considered assumptions: (1) the fit of maternal oviposition preferences with local phenotypic optimum (adaptive accuracy) and (2) the predictability of future co...

An aquatic lifestyle poses serious restriction to air-breathing animals in terms of time and energy spent during a dive cycle. The diving frequency increases with water temperature, therefore an ectotherm's time budget greatly depends on the thermal characteristics of the aquatic environment. Available data suggests that time costs caused by temper...

1. Thermal acclimation is one of the basic strategies by which organisms cope with thermal heterogeneity of the environment. Under predictable variation in environmental temperatures, theory predicts that selection favours acclimation of thermal performance curves over fixed phenotypes. 2. We examined the influence of diel fluctuations in developme...

Growth and development affect life-history traits, and consequently organismal fitness. The inevitable increase in body size during ontogeny is associated with changes in both resource use and predation risk, which results in the ontogenetic shift in habitat preferences. In this study, we examined whether the shift in preferred body temperatures (T...

A female’s decision where and when to place her eggs has important fitness consequences for her offspring. Although temperature is considered among the most relevant abiotic factors affecting female oviposition site choice in ectotherms, little is known about the relative importance of temperature cues in complex oviposition decisions. In this stud...

The position and shape of thermal performance curves (TPCs, the functions relating temperature to physiological performance) for ecologically relevant functions will directly affect the fitness of ectotherms and therefore should be under strong selection. However, thermodynamic considerations predict that relationships between the different compone...

1. The influence of interspecific hybridization on temperature preferences and morphology was examined in newts, Triturus carnifex and Triturus dobrogicus, before and after metamorphosis. 2. Thermoregulatory behavior was measured in an aquatic thermal gradient (5-32.5 degrees C) during 24 h. 3. Hybrid temperature preferences were similar to prefere...

Despite many studies demonstrating the effect of acclimation on behavioural or physiological traits, considerable debate still exists about the evolutionary significance of this phenomenon. One of the unresolved issues is whether acclimation to warmer temperature is beneficial at treatment or at more extreme test temperatures. To answer this questi...

Conflicts between structural requirements for carrying out different ecologically relevant functions may result in a compromise phenotype that maximizes neither function. Identifying and evaluating functional trade-offs may therefore aid in understanding the evolution of organismal performance. We examined the possibility of an evolutionary trade-o...

The influence of reproduction on body temperatures preferred in a laboratory thermal gradient has been studied mostly in ectotherms that are either viviparous or oviparous with prolonged egg retention. In this study I investigated whether reproduction influences temperature preferences in the Italian crested newt, Triturus carnifex (Laurenti, 1768)...

The influence of reproduction on body temperatures preferred in a laboratory thermal gradient has been studied mostly in ectotherms that are either viviparous or oviparous with prolonged egg retention. In this study I investigated whether reproduction influences temperature preferences in the Italian crested newt, Triturus carnifex (Laurenti, 1768)...

(1) Preferred temperatures were compared between fed and fasted newts with respect to their locomotor activity (LA) in an aquatic thermal gradient (5-32.5degreesC). (2) Locations and LA of 17 newts in postabsorptive phase were recorded over 24 It. (3) Nine randomly chosen newts were fed (10% of their body mass) and behaviour of all newts was record...

Zootoca vivipara is a small lizard that shows sexual dimorphism in head size. Males have larger heads than females of the same body size. By observing matings and aggressive interactions between males in the laboratory, we investigated whether this sexual dimorphism could be the result of intra- and/or intersexual selection. Winners of male±male in...

We compared preferred body temperatures, critical thermal minima, and maxima, and tolerance ranges among four populations of Zootoca vivipara (formerly Lacerta vivipara) distributed along an altitudinal gradient (250-1450 m) to examine whether different thermal environments have induced a change in these thermal characteristics. Lizards in all popu...

Injury rates (broken tails and missing toes) were studied in a population of Lacerta agilis in the Czech Republic. The frequency of regenerated tails increased continuously with snout-vent length (SVL) and did not differ between males and females. This suggests that the probability of tail breakage does not differ between age classes and sexes in t...

Melanistic individuals in one population of Zootoca vivipara in the Czech Republic were recorded. The proportion of black lizards was low (8.3%) with a significant preponderance of males (P < 0.03). Comparisons of heating rates, body sizes and body conditions did not confirm a supposed advantage of melanistic lizards. Therefore, the occurrence of b...

Sexual dimorphism and food niche competition were studied between sexes of the sand lizard Lacerta agilis living in Moravia, Czech Republic. Significant sexual differences were found in morphometric traits, with the males being smaller and lighter than females but still having larger head and legs. However, there were no differences in diet composi...

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