Abstract The study of consistent between-individual behavioural variation in single (animal personality) and across two or more behavioural traits (behavioural syndrome) is a central topic of ...behavioural ecology. Besides behavioural type (individual mean behaviour), behavioural predictability (environment-independent within-individual behavioural variation) is now also seen as an important component of individual behavioural strategy. Research focus is still on the ‘Big Five’ traits (activity, exploration, risk-taking, sociability and aggression), but another prime candidate to integrate to the personality framework is behavioural thermoregulation in small-bodied poikilotherms. Here, we found animal personality in thermoregulatory strategy (selected body temperature, voluntary thermal maximum, setpoint range) and ‘classic’ behavioural traits (activity, sheltering, risk-taking) in common lizards ( Zootoca vivipara ). Individual state did not explain the between-individual variation. There was a positive behavioural type—behavioural predictability correlation in selected body temperature. Besides an activity—risk-taking syndrome, we also found a risk-taking—selected body temperature syndrome. Our results suggest that animal personality and behavioural syndrome are present in common lizards, both including thermoregulatory and ‘classic’ behavioural traits, and selecting high body temperature with high predictability is part of the risk-prone behavioural strategy. We propose that thermoregulatory behaviour should be considered with equal weight to the ‘classic’ traits in animal personality studies of poikilotherms employing active behavioural thermoregulation.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Range shift, a widespread response to climate change, will depend on species abilities to withstand warmer climates. However, these abilities may vary within species and such intraspecific variation ...can strongly impact species responses to climate change. Facing warmer climates, individuals should disperse according to their thermal optimum with consequences for species range shifts. Here, we studied individual dispersal of a reptile in response to climate warming and preferred temperature using a semi‐natural warming experiment. Individuals with low preferred temperatures dispersed more from warmer semi‐natural habitats, whereas individuals with higher preferred temperatures dispersed more from cooler habitats. These dispersal decisions partly matched phenotype‐dependent survival rates in the different thermal habitats, suggesting adaptive dispersal decisions. This process should result into a spatial segregation of thermal phenotypes along species moving ranges which should facilitate local adaptation to warming climates. We therefore call for range shift models including intraspecific variation in thermal phenotype and dispersal decision.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Aim
Climate change is expected to cause mountain species to shift their ranges to higher elevations. Due to the decreasing amounts of habitats with increasing elevation, such shifts are likely to ...increase their extinction risk. Heterogeneous mountain topography, however, may reduce this risk by providing microclimatic conditions that can buffer macroclimatic warming or provide nearby refugia. As aspect strongly influences the local microclimate, we here assess whether shifts from warm south‐exposed aspects to cool north‐exposed aspects in response to climate change can compensate for an upward shift into cooler elevations.
Location
Switzerland, Swiss Alps.
Methods
We built ensemble distribution models using high‐resolution climate data for two mountain‐dwelling viviparous ectotherms, the Alpine salamander and the Common lizard, and projected them into various future scenarios to gain insights into distributional changes. We further compared elevation and aspect (northness) of current and predicted future locations to analyse preferences and future shifts.
Results
Future ranges were consistently decreasing for the lizard, but for the salamander they were highly variable, depending on the climate scenario and threshold rule. Aspect preferences were elevation‐dependent: warmer, south‐exposed microclimates were clearly preferred at higher compared to lower elevations. In terms of presence and future locations, we observed both elevational upward shifts and northward shifts in aspect. Under future conditions, the shift to cooler north‐exposed aspects was particularly pronounced at already warmer lower elevations.
Main conclusions
For our study species, shifts in aspect and elevation are complementary strategies to mitigate climatic warming in the complex mountain topography. This complements the long‐standing view of elevational upward shift being their only option to move into areas with suitable future climate. High‐resolution climate data are critical in heterogeneous environments to identify microrefugia and thereby improving future impact assessments of climate change.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Predation is a strong selective pressure generating morphological, physiological and behavioural responses in organisms. As predation risk is often higher during juvenile stages, antipredator ...defences expressed early in life are paramount to survival. Maternal effects are an efficient pathway to produce such defences. We investigated whether maternal exposure to predator cues during gestation affected juvenile morphology, behaviour and dispersal in common lizards (Zootoca vivipara). We exposed 21 gravid females to saurophagous snake cues for one month while 21 females remained unexposed (i.e. control). We measured body size, preferred temperature and activity level for each neonate, and released them into semi-natural enclosures connected to corridors in order to measure dispersal. Offspring from exposed mothers grew longer tails, selected lower temperatures and dispersed thrice more than offspring from unexposed mothers. Because both tail autotomy and altered thermoregulatory behaviour are common antipredator tactics in lizards, these results suggest that mothers adjusted offspring phenotype to risky natal environments (tail length) or increased risk avoidance (dispersal). Although maternal effects can be passive consequences of maternal stress, our results strongly militate for them to be an adaptive antipredator response that may increase offspring survival prospects.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
•In Western Europe, conversion of heathlands to planted forest had a severe impact on biodiversity by inducing habitat closure.•Forest edges may offer important linear habitats for ectotherm ...persistence but they remain understudied.•We demonstrate that canopy cover along edge cross-section provide a simple and useful index of microhabitat thermal quality and suitability for heliothermic reptiles.•The amount of solar radiation reaching the ground is a driver of reptiles occurrence and abundance on forest edges.•Appropriate edges management provide a relevant land sharing strategy to conciliate reptile conservation and commercial forestry.
In Western Europe, natural habitats such as heathlands have been converted into many commercially managed forests, with severe impacts on biodiversity. In dense planted forests, forest edges are often the only suitable areas for ectothermic organisms highly dependent on open habitats for thermoregulation. Surprisingly, the influence of forest edges structure on the thermal quality of microhabitats and reptile species distribution remains poorly understood. In this study, we examined two reptile species and thermal quality of interior forest edges of a coniferous forest in Western France (Brittany). We focused on two hypotheses (i) the vegetation structure of the forest edges drives the thermal quality of the habitat and (ii) structural complexity of the forest edges influences the abundance of two heliothermic reptiles: the common adder (Vipera berus) and the common lizard (Zootoca vivipara). We first deployed temperature sensitive data loggers to quantify thermal conditions along 16 cross-sections of inner forest margins. For each section, 4 temperature loggers were placed at 1, 3, 5 and 7 m from the driveway and we examined the relation to vegetation structure and canopy cover. Second, we carried visual encounter surveys in 55 edges in order to measure the response of two reptiles to the structure of the forest margin along exploitation driveway. Our results show that high local canopy cover decreases microhabitat quality within interior forest edges. We also found that common lizard abundance was significantly influenced by the edge orientation and increased with global canopy openness and ground level vegetation. Adder abundance only increased significantly with the driveway width, suggesting the unmodelled effect of other biotic/abiotic variables. Our study shows that thermal quality of interior edges and driveway characteristics are relevant to support heathland reptile populations. We posit that maintain strips of favourable microhabitats should be an efficient land sharing strategy to combine forestry activities and biodiversity conservation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Age at reproduction can influence the survival and future reproduction of an individual as well as that of their offspring. Remarkably, it has been shown that grandmaternal age at reproduction can ...also affect the characteristics of grandoffspring in humans and in laboratory or semi‐captive animals. However, currently we do not know whether grandmaternal age effects exist in wild populations.
We gathered data on female age at reproduction, offspring and grandoffspring characteristics using a 16‐year long‐term survey of a natural population of the common lizard, Zootoca vivipara. The dataset contains 579 grandoffspring from 135 litters.
Body size at birth was not correlated with grandmaternal age at reproduction. However, grandoffspring body condition at birth, grandoffspring survival and reproductive performance of granddaughters were dependent on grandmaternal age. These relationships were independent of maternal age.
An age‐structured model showed that the global effect of grandmaternal age was nonlinear and was largely driven by its effect on grandoffspring survival. Fitness was higher for granddaughters produced by grandmothers of intermediate ages.
The study shows that age can shape life‐history traits for more than one generation, documenting the importance that grandmaternal age can have in wild populations.
A free Plain Language Summary can be found within the Supporting Information of this article.
A free Plain Language Summary can be found within the Supporting Information of this article.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Male lizards often display multiple pigment‐based and structural colour signals which may reflect various quality traits (e.g. performance, parasitism), with testosterone (T) often mediating these ...relationships. Furthermore, environmental conditions can explain colour signal variation by affecting processes such as signal efficacy, thermoregulation and camouflage. The relationships between colour signals, male quality traits and environmental factors have often been analysed in isolation, but simultaneous analyses are rare. Thus, the response of multiple colour signals to variation in all these factors in an integrative analysis remains to be investigated.
Here, we investigated how multiple colour signals relate to their information content, examined the role of T as a potential mediator of these relationships and how environmental factors explain colour signal variation.
We performed an integrative study to examine the covariation between three colour signals (melanin‐based black, carotenoid‐based yellow–orange and structural UV), physiological performance, parasitism, T levels and environmental factors (microclimate, forest cover) in male common lizards Zootoca vivipara from 13 populations.
We found that the three colour signals conveyed information on different aspects of male condition, supporting a multiple message hypothesis. T influenced only parasitism, suggesting that T does not directly mediate the relationships between colour signals and their information content. Moreover, colour signals became more saturated in forested habitats, suggesting an adaptation to degraded light conditions, and became generally brighter in mesic conditions, in contradiction with the thermal melanism hypothesis.
We show that distinct individual quality traits and environmental factors simultaneously explain variations of multiple colour signals with different production modes. Our study therefore highlights the complexity of colour signal evolution, involving various sets of selective pressures acting at the same time, but in different ways depending on colour production mechanism.
Résumé
Les lézards mâles arborent souvent plusieurs signaux colorés de nature pigmentaire et structurale qui reflètent de multiples traits de qualité (e.g. performance, parasitisme), et la testostérone (T) joue souvent un rôle de médiateur dans ces relations. En outre, les conditions environnementales peuvent également expliquer les variations des signaux colorés en influençant des aspects tels que l'efficacité des signaux, la thermorégulation ou le camouflage. Les relations entre signaux colorés, traits de qualité individuelle et facteurs environnementaux ont souvent été analysées séparément, mais rarement de manière simultanée. Ainsi, la réponse de ces multiples signaux colorés aux variations de tous ces facteurs reste à explorer dans le contexte d'une étude intégrative.
Ici, nous explorons la relation entre ces multiples signaux colorés et leur contenu informatif, nous examinons le rôle de T comme médiateur potentiel de ces relations et nous recherchons si les conditions environnementales expliquent la variation de ces signaux colorés.
Nous avons mené une étude intégrative afin d'examiner la covariation entre trois types de signaux colorés (noir produit par la mélanine, jaune‐orange produit par les caroténoïdes et UV produit par des éléments structuraux), la performance physiologique, le parasitisme, les niveaux de T et les conditions environnementales (e.g. microclimat, couverture forestière) chez des mâles du lézard vivipare (Zootoca vivipara) provenant de 13 populations.
Nos résultats indiquent que les trois signaux colorés transmettent des informations sur différents aspects de la condition des mâles, en accord avec l'hypothèse de « messages multiples ». T influence uniquement le parasitisme, suggérant que T n'agit pas en tant que médiateur des relations entre ces signaux colorés et leur contenu informatif. De plus, les signaux colorés sont plus saturés dans les habitats les plus forestiers, ce qui suggère une adaptation à des conditions lumineuses dégradées. Enfin, les signaux colorés sont plus intenses lorsque les conditions sont mésiques, en contradiction avec l'hypothèse du mélanisme thermal.
Nous démontrons que différents traits de qualité individuelle et facteurs environnementaux expliquent de manière simultanée les variations de multiples signaux colorés impliquant différents modes de production. Notre étude souligne ainsi la complexité de l'évolution des signaux colorés, qui implique plusieurs types de pressions de sélection agissant en même temps mais dans des directions différentes selon le mode de production.
Using the common lizard, Zootoca vivipara, this work shows that three different colour signals convey information on different aspects of male quality (performance, parasitism, body size), and at the same time covary with environmental factors such as forest cover, climate and ecogeography.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
According to animal signalling theory, social costs incurred by aggressive conspecifics are one mechanism maintaining signal honesty. Although our understanding of signal evolution has much ...improved for pigment-based colours, the mechanisms maintaining the honesty of structural colour signals, such as ultraviolet (UV), remain elusive. Here, we used the common lizard (Zootoca vivipara) to test whether the honesty of UV-reflecting signals displayed on male throats is under social control. To do so, we staged agonistic interactions between non-manipulated focal males and opponents of either larger or smaller body size. We manipulated the UV component of the male throat colour patch to create small cheaters with UV-enhanced throats, large cheaters with UV-reduced throats, and their respective controls. In support of a conventional signal hypothesis, focal males were aggressive towards large cheaters and became submissive when these large cheaters retaliated, and were less submissive against small cheaters. However, that focal males were not more aggressive towards small cheaters contradicts our initial predictions. We confirm that male UV reflectance and bite force were good predictors of contest outcomes in control conditions. Overall, we provide partial evidence suggesting that social costs enforce UV signal honesty in common lizards.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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