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Behavioural syndromes. Diagram illustrating the between-individual correlations (rind) among traits. For chronotypes-personality correlations, the estimates were obtained from the LMMs for each laboratory-based behavioural trait (exploration, activity, boldness, aggressiveness), considering only the effects of chronotypes (activity onset and rest onset). For personality correlations, the estimates were obtained from the MGLMMs. In both cases, the value represents the rind with their corresponding confidence intervals shown in square brackets. Significant correlations are depicted by thicker lines and values in black, while non-significant correlations are shown with thinner lines and values in grey.
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Chronotypes, the individual differences in daily activity timing, have profound associations with numerous physiological processes. Despite this, the covariance between chronotypes and other aspects of an individual's behaviour has been infrequently explored in non-human animals. This study delves into individual's variation across four axes of per...
Citations
... An effective approach to gather knowledge on the matter involves observation of the targeted species within corresponding native habitats, in order to gain insights regarding natural behavior dynamics and responses to environmental stimuli Martorell-Barceló et al., 2023). By studying how fish larvae interact with their surroundings and other organisms can lead to a comprehensive understanding of their unique requirements for optimal growth and development (Ribeiro et al., 2022). ...
... This interindividual variability has relevant ecological implications for the fitness of the species, both in natural settings and when the population is exploited by fisheries (Martorell-Barceló et al. 2018). Furthermore, behavioural studies in the laboratory , 2023 demonstrated the adaptability of this species to captive conditions, enabling testing of individuals under controlled environmental cues. ...
Most organisms synchronize to an approximately 24-hour (circadian) rhythm. This study introduces a novel deep learning-powered video tracking method to assess the stability, fragmentation, robustness and synchronization of activity rhythms in Xyrichtys novacula. Experimental X. novacula were distributed into three groups and monitored for synchronization to a 14/10 hours of light/dark to assess acclimation to laboratory conditions. Group GP7 acclimated for 1 week and was tested from days 7 to 14, GP14 acclimated for 14 days and was tested from days 14 to 21 and GP21 acclimated for 21 days and was tested from days 21 to 28. Telemetry data from individuals in the wild depicted their natural behavior. Wild fish displayed a robust and minimally fragmented rhythm, entrained to the natural photoperiod. Under laboratory conditions, differences in activity levels were observed between light and dark phases. However, no differences were observed in activity rhythm metrics among laboratory groups related to acclimation period. Notably, longer acclimation (GP14 and GP21) led to a larger proportion of individuals displaying rhythm synchronization with the imposed photoperiod. Our work introduces a novel approach for monitoring biological rhythms in laboratory conditions, employing a specifically engineered video tracking system based on deep learning, adaptable for other species.
... In contrast, starting activity early may not be necessary to more aggressive individuals. Therefore, we predict a positive correlation between chronotype and aggression, as has been reported in pearly razor fish, Xyrichtys novacula (Martorell-Barcel o et al., 2023). ...
Individual variation in the timing of activities is increasingly being reported for a wide variety of species, often measured as the timing of activity onset in the morning. However, so far, the adaptive significance of consistent variation in temporal phenotypes (i.e. the chronotype) remains largely elusive. Potentially, differences in timing of activities may arise as a result of competition among individuals for resources. Less aggressive individuals may try to avoid competition by becoming active earlier during the day when other individuals are still inactive, leading to a positive correlation between chronotype and aggressive personality type (i.e. a behavioural syndrome). To investigate this, we assessed the chronotype of female great tits, Parus major, by measuring emergence time from the nestbox in the morning and experimentally tested their levels of same-sex aggression through simulated territorial intrusion tests. Contradicting our initial hypothesis, consistently more aggressive females became active earlier during the day compared to less aggressive females, which could be caused by shared underlying mechanisms, like pleiotropic effects of sex hormones or gene pleiotropy, which potentially impose constraints on the independent evolution of both traits. Surprisingly, on the within-individual level we found an opposing correlation between emergence time and aggression. Our findings highlight the need for further investigations into the interplay between chronotype and aggression that take the underlying mechanisms into account in order to understand the adaptive significance of this trait association.
Domestication is a process in which animals are bred in captivity under controlled resource availability. Compared with wild-type phenotypes, animals with domesticated phenotypes exhibit reduced stress sensitivity and cognitive abilities. The pigmentation of domesticated phenotype animals is a morphological change, one of those that is considered a “domestication syndrome”. In fish, the impact of pigmentation on behaviour and physiology has rarely been examined. We compared the performance of two phenotypes of the common carp Cyprinus carpio: a wild-coloured phenotype and an orange-coloured phenotype of koi carp. The fish were exposed to short-term stress conditions, after which blood samples were collected to obtain biochemical indices. The maze and field experiments were used to observe individuals' movement activity, exploratory behaviour, and ability to find food in the experimental maze. The fish were equipped with radio tags for the field experiment. In the riverine environment, movement activity and preferred temperatures during light/dark cycles were observed. Presuming that the orange-coloured carp exhibit reduced cognitive ability, we hypothesized that they would exhibit i) reduced exploratory behaviour and ii) lower stress sensitivity than wild-coloured carp. Our results revealed mostly nocturnal activity in koi carp. The koi carp needed more time to explore the maze, as expected, but contrary to our assumption they showed greater stress levels accompanied by greater movement activity. This behaviour was similar for different maze setting. The wild-coloured carp were active during both day and night and exhibited greater left-sided lateralization and cognitive skills, allowing them to find food faster. For the wild-coloured phenotype, body temperature was significantly correlated with all the other observed variables. Our results suggest potentially lower welfare of the koi carp in mixed aquaculture, e.g., a lower ability to use feeding resources than the wild-coloured carp.
