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Identifying evolutionary and developmental mechanisms underlying consistent between‐individual differences in behaviour is the main goal in ‘animal personality studies’. Here, we explored whether activity and risk‐taking varied consistently between individuals and correlated to various – potentially fitness linked – male traits in Carpetan rock lizards (Iberolacerta cyreni). Lizards showed significant consistency within both behaviours, implying the presence of activity and risk‐taking personalities. However, there were no correlation between activity and risk‐taking, neither on the between‐ nor on the within‐individual levels, implying the absence of a behavioural syndrome. We found a strong link between the intensity of blood parasite (Haemogregarinidae) infection and risk‐taking: lizards with higher infection intensity took more risk. While we cannot distinguish cause from causative in the parasite intensity – risk‐taking correlation – our results are in line with the asset protection hypothesis predicting that individuals with lower future reproductive value should focus on the current reproductive event and take higher risk.

Behaviour is one of the most plastic quantitative traits in animals (West-Eberhard, 2003). 47However, between-individual behavioural variation in the same context and situation became 48 accepted as a valid and biologically important phenomenon lately (Gosling, 2001; Sih et al. 49 2004a Sih et al. 49 , 2004bSmith and Blumstein, 2008;Stamps, 2007;Wilson, 1998). Individual 2014). Behavioural consistency could be seen as a disadvantageous trait, since it constraints 54 plasticity and thus limits the individual behavioural repertoire, which might be maladaptive in 55 variable environments and certain contexts (Bell, 2005(Bell, , 2007 Dzieweczynski and Hebert, 56 2013; Sih et al. 2012Sih et al. , 2004a. Thus, for instance, an individual aggressive towards conspecific 57 competitors remains aggressive in other contexts (e.g. towards predators / during mating) 58 when this behaviour is likely to decrease fitness (e.g. Berning et al. 2012). Hence, one of the 59 most important aims of current evolutionary behavioural ecology is to understand the ultimate 60 and proximate mechanisms that resulted in the emergence of behavioural consistency. 62Estimating individual quality or 'true' fitness is notoriously hard, and thus linking animal 63 personality to individual quality is not straightforward in most possible models. Further, 64 individual quality could mean different things to different researchers, and even proxies of 65 quality might depend on the conceptual framework of the study (Wilson and Nussey, 2010; 66 Bergeron et al. 2011). One possible solution for non-model species is to focus on ecologically 67 4 relevant traits with proven, or at least highly probable, link to fitness. Establishing the 68 relationships between them and personality would be relevant for understanding how 69 behavioural consistency emerges in nature. 71European green lizard (Lacerta viridis) is an excellent candidate for such a study. Males have 72 ultraviolet-blue nuptial throat colouration that is a multiple honest signal and has important 73 roles in both intra-and intersexual selection (Bajer et al. 2010(Bajer et al. , 2011(Bajer et al. , 2012 Molnár et al. 74 2012 Molnár et al. 74 , 2013 Vaclav et al. 2007). Other morphological traits have also been shown to be 75 important determinants of lizards' fitness, like the number and symmetry of femoral pores 76 (Lopez et al 2002) or the size of head (Gvozdik and Van Damme, 2003;Roughgarden, 1974; 77 Vitt, 2000). One can also include traits that are known to be strongly connected to fitness in 78 almost any species, like body size or body condition (Peters 1983;Roff 1992;Stearns 1992 Bajer et al. 2012Bajer et al. , 2011Bajer et al. , 2010 Molnár et al. 2013 Molnár et al. , 2012: (1) 154 brightness: the total reflectance from 320 and 700 nm; (2) UV chroma (relative UV intensity): 155 the percent of reflectance measured in the UV range compared to total reflectance (R 320-156 400 /R 320-700 ); and (3) blue chroma (relative blue intensity): the perc...

Most studies on animal personality evaluate individual mean behaviour to describe individual behavioural strategy, while often neglecting behavioural variability on the within-individual level. However, within-individual behavioural plasticity (variation induced by environment) and within-individual residual variation (regulatory behavioural precision) are recognized as biologically valid components of individual behaviour, but the evolutionary ecology of these components is still less understood. Here, we tested whether behaviour of common pill bugs (Armadillidium vulgare) differs on the among-and within-individual level and whether it is affected by various individual specific state-related traits (sex, size and Wolbachia infection). To this aim, we assayed risk-taking in familiar vs. unfamiliar environments 30 times along 38 days and applied double modelling statistical technique to handle the complex hierarchical structure for both individual-specific trait means and variances. We found that there are significant among-individual differences not only in mean risk-taking behaviour but also in environment-and time-induced behavioural plasticity and residual variation. Wolbachia-infected individuals took less risk than healthy conspecifics; in addition, individuals became more risk-averse with time. Residual variation decreased with time, and individuals expressed higher residual variation in the unfamiliar environment. Further, sensitization was stronger in females and in larger individuals in general. Our results suggest that among-individual variation, behavioural plasticity and residual variation are all (i) biologically relevant components of an individual's behavioural strategy and (ii) responsive to changes in environment or labile state variables. We propose pill bugs as promising models for personality research due to the relative ease of getting repeated behavioural measurements.

Behavioral innovation is a key process for successful colonization of new habitat types. However, it is costly due to the necessary cognitive and neural demands and typically connected to ecological generalism. Therefore, loss of behavioral innovativeness is predicted following colonization of new, simple, and invariable environments. We tested this prediction by studying foraging innovativeness in the freshwater isopodAsellus aquaticus. We sampled its populations along the route of colonizing a thermokarstic water‐filled cave (simple, stable habitat with only bacterial mats as food) from surface habitats (variable environment, wide variety of food). The studied cave population separated from the surface populations at least 60,000 years ago. Animals were tested both with familiar and novel food types (cave food: bacterial mats; surface food: decaying leaves). Irrespective of food type, cave individuals were more likely to feed than surface individuals. Further, animals from all populations fed longer on leaves than on bacteria, even though leaves were novel for the cave animals. Our results support that caveA. aquaticusdid not lose the ability to use the ancestral (surface) food type after adapting to a simple, stable, and highly specialized habitat.

Understanding the background mechanisms affecting the emergence and maintenance of consistent between-individual variation within population in single (animal personality) or across multiple (behavioural syndrome) behaviours has key importance. State-dependence theory suggests that behaviour is ‘anchored’ to individual state (e.g. body condition, gender, age) and behavioural consistency emerges through behavioural-state feedbacks. A number of relevant state variables are labile (e.g. body condition, physiological performance) and expected to be affected by short-term environmental change. Yet, whether short-term environmental shifts affect behavioural consistency during adulthood remains questionable. Here, by employing a full-factorial laboratory experiment, we explored if quantity of food (low vs. high) and time available for thermoregulation (3h vs. 10h per day) had an effect on activity and risk-taking of reproductive adult male European green lizards (Lacerta viridis). We focussed on different components of behavioural variation: (i) strength of behavioural consistency (repeatability for animal personality; between-individual correlation for behavioural syndrome), (ii) behavioural type (individual mean behaviour) and (iii) behavioural predictability (within-individual behavioural variation). Activity was repeatable in all treatments. Risk-taking was repeatable only in the low basking treatments. We found significant between-individual correlation only in the low food × long basking time group. The treatments did not affect behavioural type, but affected behavioural predictability. Activity predictability was higher in the short basking treatment, where it also decreased with size (≈ age). Risk-taking predictability in the short basking treatment increased with size under food limitation, but decreased when food supply was high. We conclude that short-term environmental change can alter various components of behavioural consistency. The effect could be detected in the presence/absence patterns of animal personality and behavioural syndrome and the level of individual behavioural predictability, but not in behavioural type.

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Mechanisms affecting consistent interindividual behavioral variation (i.e., animal personality) are of wide scientific interest. In poikilotherms, ambient temperature is one of the most important environmental factors with a direct link to a variety of fitness‐related traits. Recent empirical evidence suggests that individual differences in boldness are linked to behavioral thermoregulation strategy in heliothermic species, as individuals are regularly exposed to predators during basking. Here, we tested for links between behavioral thermoregulation strategy, boldness, and individual state in adult males of the high‐mountain Carpetan rock lizard (Iberolacerta cyreni). Principal component analysis revealed the following latent links in our data: (i) a positive relationship of activity with relative limb length and color brightness (PC1, 23% variation explained), (ii) a negative relationship of thermoregulatory precision with parasite load and risk‐taking (PC2, 20.98% variation explained), and (iii) a negative relationship between preferred body temperature and relative limb length (PC3, 19.23% variation explained). We conclude that differences in boldness and behavioral thermoregulatory strategy could be explained by both stable and labile state variables. The moderate link between behavioral thermoregulatory strategy and risk‐taking personality in our system is plausibly the result of differences in reproductive state of individuals or variation in ecological conditions during the breeding season.