In captivity, reptiles often experience unnatural incubation and rearing conditions due to limited nest site choices, which can negatively impact individual development and welfare. Incubation temperature and humidity are especially critical for reptile development, influencing factors such as sex, growth and morphology. However, the conditions experienced after hatching, such as social housing, are far less often considered. Here, I studied the effects of both the incubation environment (temperature and humidity) and social rearing compared to isolation rearing on the development of captive-bred tokay geckos (Gekko gecko). I find that incubation temperature, but not humidity are associated with phenotypic sex, hatchling size and incubation duration. Furthermore, females selected nest sites with higher temperature and lower humidity. After hatching, rearing group size did not affect snout vent length, growth or body condition. My findings indicate an association between incubation temperature and phenotypic sex despite the presence of sex chromosomes in this species. Therefore, care should be taken when raising tokay geckos in captivity to provide nest-site options and ensure optimal development of all offspring.

Reptiles are increasingly popular as exotic pets and can suffer high mortality risks in captivity, yet research into their welfare remains limited. Commonly occurring practices such as frequent handling, changes in housing and diet could induce stress and increase parasite loads with potentially severe negative welfare outcomes. Therefore, it is crucial to understand how routine procedures may influence parasite infections. In this study, we exposed captive bred tokay geckos (Gekko gecko) to two stressors common in the reptile trade, cohabitation with a novel conspecific and a change in diet. We tested the effect of a diet and housing change on oxyurid egg shedding intensity in isolation as well as the combined effect of both treatments. We found that a change in diet or housing alone had no effect on fecal parasite load while both a change in diet and housing combined did increase parasite load. However, we did not notice a visible change in the lizards’ body condition, food and water uptake or defecation within the short study period. Our study shows that common changes in housing and husbandry can increase parasite load in tokay geckos. Further studies are needed to determine which other procedures (e.g., confinement, transport, novel environments) affect health and when combined could severely impact reptile health.

Spatial memory is a fundamental cognitive process that allows animals to navigate and interact with their environment effectively. While extensively studied in mammals and birds, the mechanisms underlying spatial cognition in reptiles remain less understood. In this study, we investigated spatial learning and the influence of behavioural lateralization in the common wall lizard (Podarcis muralis). We examined whether lizards could develop short-term spatial memory and whether lateralization affected their navigation in a complex maze. Experimental lizards received 3 days of training without reinforcement, while control lizards had no prior experience. We found that trained lizards learnt to navigate the maze rapidly, reaching a goal shelter faster and more reliably than controls. Additionally, strongly lateralized individuals took longer to reach the goal during training, but this did not impair escape performance once the route had been learned. Our study reports novel evidence on the role of lateralization during spatial exploration in lizards. Lateralization is hypothesized to enhance information processing, but our data suggest no benefit or cost of lateralization after a route was learnt. Our study contributes to a broader understanding of cognitive evolution across vertebrates and emphasizes the importance of reptiles as models for comparative cognition research.

Pair bonding is a key social behavior but remains understudied in reptiles despite a growing body of evidence suggesting that some species exhibit complex sociality. The lack of evidence regarding the expression of pair association in social lizard species hampers our understanding of its effects on captive welfare. As a first step towards a better understanding of pair-related social behavior in lizards, we investigated if physical closeness, a measure often used to qualify pair bonding in mammals and birds, can be used to assess pair association strength in 25 captive tokay geckos (Gekko gecko). We analyzed how physical closeness is related to measures of spatial behavior collected through scan sampling across two sampling years. Physical closeness was not related to movement but to hiding and basking behavior, albeit not consistently across years (e.g., negative in one year and positive in the other). We also show that although, on average, our measure of pair association strength did not change across the experimental period, individuals that were paired with new individuals in 2024 exhibited a change (increase or decrease). It is unknown if differences occur in the wild and if they confer different fitness outcomes. However, our results have implications for captive welfare, and we propose to monitor socially housed individuals closely to avoid unnecessary socially induced stress.

The ability to adapt behaviour flexibly to the current situation, also referred to as 'behavioural flexibility', is crucial for survival and reproductive success. The early social environment is an important driver of variation in cognitive abilities including behavioural flexibility. However, few studies have investigated this relationship across contexts. Likewise, few studies have investigated the development of modular versus general cognition (i.e. inconsistent versus consistent performance across social and nonsocial contexts) in social species. Here, (1) we investigated the influence of the early social environment (rearing group size) on behavioural flexibility in adult helpers of a cooperatively breeding cichlid fish (Neolamprologus pulcher) and (2) we assessed the presence of general or modular cognition irrespective of early experience by using three nonsocial flexibility tests (innovation test, reversal learning, set shifting) and two social flexibility tests (hierarchy test, integration test). Overall, early social experience only influenced social but not nonsocial flexibility. Helpers raised in large social groups were less flexible in the hierarchy test but tended to be accepted more often when integrated with an unfamiliar breeding pair, compared to fish raised in small groups. The early social environment did not affect nonsocial flexibility, although fish were able to adjust behaviour flexibly in both social and nonsocial contexts. For all fish, performances were not correlated across tests, implying the existence of domain-specific cognition. Nevertheless, results of a principal component analysis suggest an association between performances in social and nonsocial contexts, which may hint at domain-general cognition, albeit with the caveat that not all tests were associated with the same principal component. Future research should develop approaches that can clearly distinguish between general and modular cognition, and that compare species with different environmental predictability. (c) 2024 The Authors. Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. This is an open access article under the CC BY license (http://creativecommons.org/licenses/ by/4.0/).

How cognition evolved remains a debated “hot-topic” in the field of animal cognition. Current hypotheses link variation in sociality, ecology, and more generally, environmental challenges to differences in cognitive development, both between as well as within species. Research supporting the Social Intelligence Hypothesis, which states that cognition evolved to deal with social challenges, is largely focused on highly social mammal and bird species, limiting our ability to evaluate the general applicability of the hypothesis. Unfortunately, developmental studies which can reveal the causal link between early life experiences and cognitive development are scare. The aim of this study was to test the effect of the early post-natal social environment on the development of neophobia, exploration, food motivation, habituation and associative learning in a social lizard, the tokay gecko (Gekko gecko). We did not find evidence that the early social rearing environment influenced object neophobia. However, our results show that the early social environment influenced the time taken to enter a novel space and the variation in associative learning. We discuss our findings in the light of the Social Intelligence Hypothesis taking into account the facultative sociality nature of our study system. Our study provides new insight into how cognitive benefits associated with group living might have promoted the evolution of more complex social structures in animals.

Animals need to recognize different individuals, both con- and heterospecifics, to make appropriate decisions. In the wild, responses to familiar individuals may vary depending on the context, which can be beneficial. However, differing responses towards human experimenters can influence experimental outcomes. Such effects might be particularly overlooked in reptiles which are frequently viewed as cognitively less advanced. We tested Tokay geckos’ (Gekko gecko) ability to distinguish between familiar and unfamiliar handlers in two situations: in a novel situation (exerting physical constraint) and a routine situation (feeding from forceps as during regular husbandry). Geckos showed sex-specific differences towards familiar and unfamiliar handlers in a routine situation, but not in a novel situation, in which they showed individual repeatability. Our results further advance our understanding of reptile cognition revealing important insights into context specific responses in relation to handler identity with implications for experimental animal studies that are rarely considered.

The drivers of differences in cognitive ability, within as well as across species, remain a debated "hot-topic" in animal cognition. Current hypotheses link variation in sociality, ecology, and more generally, environmental challenges to differences in cognition. Research supporting the social intelligence hypothesis, which states that cognition evolved to deal with the challenges of interacting with conspecifics, is largely focused on highly social mammal and bird species, limiting our ability to evaluate the general applicability of the hypothesis. Furthermore, it is unclear whether the social environment facilitates cognitive development or if selection acts against individuals with low cognitive abilities in social groups. Unfortunately, developmental studies which can reveal the causal link between early life experiences and cognitive development are scarce. Therefore, we aimed to test the effect of the early post-natal social environment on the development of behavior and cognition in a social lizard, the tokay gecko (Gekko gecko). Our results show that the early social environment influenced the development of boldness and the variation in space neophobia and associative learning. We discuss our findings in the light of the social intelligence hypothesis, taking into account the facultative social nature of our study system.

Publishing preprints is quickly becoming commonplace in ecology and evolutionary biology. Preprints can facilitate the rapid sharing of scientific knowledge establishing precedence and enabling feedback from the research community before peer review. Yet, significant barriers to preprint use exist, including language barriers, a lack of understanding about the benefits of preprints and a lack of diversity in the types of research outputs accepted (e.g. reports). Community-driven preprint initiatives can allow a research community to come together to break down these barriers to improve equity and coverage of global knowledge. Here, we explore the first preprints uploaded to EcoEvoRxiv (n = 1216), a community-driven preprint server for ecologists and evolutionary biologists, to characterize preprint use in ecology, evolution and conservation. Our perspective piece highlights some of the unique initiatives that EcoEvoRxiv has taken to break down barriers to scientific publishing by exploring the composition of articles, how gender and career stage influence preprint use, whether preprints are associated with greater open science practices (e.g. code and data sharing) and tracking preprint publication outcomes. Our analysis identifies areas that we still need to improve upon but highlights how community-driven initiatives, such as EcoEvoRxiv, can play a crucial role in shaping publishing practices in biology.

The Social Intelligence Hypothesis suggests that cognition might be key to enable animals to live in social groups. Especially social cognition is important as it allows animals to respond appropriately to conspecifics and ensure group cohesion. Social cognition is extensively studied in mammals and birds but to gain a broad understanding of the benefits of social cognitive processes in social interactions we need a broader phylogenetic approach. In this opinion paper, I suggest Squamates (lizards, snakes, and worm lizards) as promising models due to their diverse but facultative sociality and reliance on semiochemical communication in social contexts. Squamates possess a highly developed vomeronasal system to detect semiochemicals for social recognition and discrimination. Similar to the well-studied rodents, squamates detect a wide range of information within chemical cues but research on the associated decision-making processes, individual differences and development of these abilities is still scarce. Comparative approaches leveraging Squamates' semiochemical communication and sociobiological diversity could provide important new insights into the evolution of social cognition. Future research should further focus on individual abilities, their link to environmental and social demands, and consequences for fitness, advancing our understanding of adaptive social cognitive skills across taxa.

Spatial memory is fundamental cognitive process that allows animals to navigate and interact with their environment effectively. While extensively studied in mammals and birds, the mechanisms underlying spatial cognition in reptiles remain less understood. In this study, we investigated spatial learning and the potential influence of behavioural lateralisation in the common wall lizard (Podarcis muralis). Using a T-maze, we examined whether lizards could develop short-term spatial memory and whether lateralisation affected their navigation. Experimental lizards received three days of training in the maze without reinforcement, while control lizards had no prior experience. We found that trained lizards rapidly learnt to navigate, reaching a goal shelter faster and more reliably than controls. Additionally, only seven out of twenty individuals exhibited lateralised turning behaviour. Nevertheless, strongly lateralised individuals took longer to reach the goal during training, but this did not necessarily impair performance once the route had been learned. These findings align with research in other taxa, where lateralised individuals often show context-dependent differences in performance, sometimes outperforming non-lateralised individuals under stress. This study contributes to a broader understanding of cognitive evolution across vertebrates and emphasizes the importance of reptiles as models for comparative cognition research.

Reptiles are increasingly popular as exotic pets and suffer high mortality especially in the first year in captivity, yet research into their welfare remains limited. Reptiles are often infected by parasites. One common taxon is Oxyuroidea superfamily, which has a direct life cycle that promotes easy transmission in enclosed environments. Due to limited ecological knowledge, inappropriate husbandry practices are common in reptiles causing stress and increased parasite loads leading to severe health issues. Therefore, it is crucial to understand how routine captive procedures may influence parasite infections. In this study, we exposed captive bred tokay geckos ( Gekko gecko) to two stressors common in the reptile trade, cohabitation with a novel conspecific and a change in diet. We tested their effect on fecal oxyurid output compared to a control group as well as their combined effect. We found that a single stressor had no effect on fecal parasite load while both combined did significantly increase parasite load. However, we did not find a detectable change in the lizards’ general condition. Our study shows that seemingly minor changes in housing and husbandry can exert stress and increase parasite load in tokay geckos. Further studies are needed to determine which other procedures (e.g. confinement, transport, novel environments) affect health and when combined could lead to more severe changes in health in reptiles. Summary Many reptiles are infected with parasites that can lead to health issues. Routine husbandry procedures such as new conspecifics and diet are stressful and lead to a higher parasite load in geckos. ### Competing Interest Statement The authors have declared no competing interest. Ghent University, https://ror.org/00cv9y106, 01M00221 University of Bern, https://ror.org/02k7v4d05, NA

Animals need to distinguish among different con- and heterospecific individuals to be able to adjust behaviour appropriately. Behavioural responses towards familiar individuals might vary based on context in which they are encountered. However, such context dependent responses, while beneficial in the wild, can impact experimental results, increase error, decrease reproducibility and threaten scientific advancement. Consequently, it is essential to understand how and when experimenters influence animal behaviour. Here, we tested captive Tokay geckos (Gecko gecko) ability to discriminate familiar and unfamiliar handlers across two situations (novel and routine). In the novel situation, we induced tonic immobility through physical constraint, a protocol the animals had never experienced before. In the routine situation, we fed lizards live prey with tweezers (as during regular husbandry). Geckos behaved differently towards familiar and unfamiliar handlers in a routine situation but not in an novel situation. Nevertheless, we found high individual repeatability in tonic immobility (R = 0.41-0.56). Our study, therefore, has implications for animal behaviour, cognition and welfare, while revealing important insights into context specific responses in relation to handler identity, factors that are rarely considered in experimental animal studies but that can significantly impact results.

Here, we explore the first preprints uploaded to EcoEvoRxiv to characterise preprint practices in ecology and evolution. We aim to understand: 1) in what countries authors who use EcoEvoRxiv are located; 2) the taxonomic diversity of study systems across preprints; 3) whether preprint server use depends on career stage and gender; 4) the extent to which authors make use of preprint servers for reports and community-driven peer review; 5) the extent to which data and code are shared in preprints; and 6) how many preprints remain unpublished, and for those that are published, how long it took for them to become published. In the process, we also provide a summary of what makes EcoEvoRxiv distinct from other preprint servers to help further clarify the benefits of using community-driven preprint servers to disseminate research findings.

Animals employ quantitative abilities to gauge crucial aspects of their environment, such as food or predator density in a given area or the number of eggs in a nest. These quantitative skills hold ecological implications and can impact an animal's fitness. However, our comprehension of how these abilities intersect with environmental challenges remains limited. We tested for spontaneous quantity discrimination in the sleepy lizard (Tiliqua rugosa), a long-lived species known for forming life-long pair bonds in which pairs come together for the breeding season. We subjected lizards to a Y-maze experiment presenting both discrete (comparisons involving two vs. four, two vs. six, two vs. eight, four vs. six, four vs. eight, and six vs. eight pieces) and equivalent continuous combinations (single pieces differing in size) of pumpkin pieces. Our findings revealed that sleepy lizards exhibited spontaneous quantity discrimination, favoring the larger quantity in three discrete comparisons (eight vs. two, two vs. six, four vs. six) and two continuous comparisons (eight vs. two, eight vs. four). However, low accuracy may be attributable to difficulty in visual acuity exacerbated by difficulty discriminating quantities at small ratios. Furthermore, we found no evidence for a speed-accuracy trade-off in their decision-making process. Our results suggest that sleepy lizards likely employ multiple cues to estimate quantity accurately. Considering these results in the context of previous studies on various lizard species, it becomes apparent that lizards, as a group, offer a valuable model for unraveling the evolution of cognition, given their diverse ecology and sociobiology.

Urbanization occurs at a global scale, imposing dramatic and abrupt environmental changes that lead to biodiversity loss. Yet, some animal species can handle these changes, and thrive in such artificial environments. One possible explanation is that urban individuals are equipped with better cognitive abilities, but most studies have focused on birds and mammals and yielded varied results. Reptiles have received much less attention, despite some lizard species being common city dwellers. The Italian wall lizard, Podarcis siculus, and the common wall lizard, Podarcis muralis, are two successful lizards in anthropogenic habitats that thrive in urban locations. To test for differences in a cognitive skill between urban and semi-natural environments, we investigated inhibitory control through a detour task in syntopic populations of the two species, across 249 lizards that were tested in partially artificial field settings. Sophisticated inhibitory control is considered essential for higher degrees of cognitive flexibility and other higher-level cognitive abilities. In this task, we confronted lizards with a transparent barrier, separating them from a desired shelter area that they could only reach by controlling their impulse to go straight and instead detour the barrier. We found no differences between lizards in urban and semi-natural environments, nor between species, but females overall performed better than males. Moreover, 48% of the lizards in our study did not perform a correct trial in any of the 5 trials, hinting at the difficulty of the task for these species. This study is among the first to address lizard cognition, through their inhibitory control, as a potential explanation for success in cities and highlights one should be careful with assuming that urban animals generally have enhanced cognitive performance, as it might be taxa, task, or condition dependent.

Due to often insufficient information reptiles suffer welfare issues and increased mortality in captivity. In particular, the impact of the social environment remains poorly understood, despite evidence suggesting its’ importance for welfare in a wide range social animals. The current study investigated how pair housing changes enclosure use, basking and hiding behaviour in tokay geckos (Gekko gecko). While the captive conditions and husbandry procedures employed in this study align with existing literature recommendations, they have not been previously evaluated for their suitability for this particular species. The results show that, when socially deprived, lizards were more likely to move and hide before feeding. Furthermore, males were more likely to be found at the front than females during pair housing but not during single housing. Finally, contrary to single housing, enclosure temperature had no effect on the probability to move and hide behind a shelter during pair housing. Consistently, lizards were more likely to bask after feeding across housing conditions, and females were more likely to bask before their first clutch. Together, pair housing decreases movement and hiding in relation to human presence (feeding), which might indicate that pair housing improves tokay gecko welfare and suggest that the presence of a conspecific should be considered to improve welfare policies in social reptiles. This study serves as a baseline for future research into how enclosure furnishings, husbandry techniques, and enrichment practices impact the welfare of tokay geckos which will be crucial for refining our understanding of and improving on the welfare of reptiles in captivity.

Social animals need to keep track of other individuals in their group to be able to adjust their behaviour accordingly and facilitate group cohesion. This recognition ability varies across species and is influenced by cognitive capacities such as learning and memory. In reptiles, particularly Squamates (lizards, snakes, and worm lizards), chemical communication is pivotal for territoriality, reproduction, and other social interactions. However, the cognitive processes underlying these social interactions remain understudied. In our study, we examined the ability of male and female Tokay geckos (Gekko gecko) to chemically differentiate familiar and unfamiliar mating partners. Our findings suggest that both sexes can make this distinction, with males responding more to the odour of a familiar mate, and females responding more to unfamiliar mates. The lizards maintained their discriminatory abilities for two to three weeks but not up to six weeks after separation. This research highlights the efficacy of using odours as social stimuli for investigating social cognition in lizards, a promising avenue to better understand social cognition in these animals.