Biology subjects

Bugnyar, T.

Publications and source records attributed to Bugnyar, T..

5 recordsLinked to original sources

bioRxiv2026

The BEAC, an epigenetic clock for birds

Epigenetic clocks are powerful tools for estimating both chronological and biological age, enabling the integration of age information into population monitoring, demographic modelling, and research on the ecophysiology and evolution of ageing. Most epigenetic clocks so far have been developed for mammals: here, we present the Bird Epigenetic Ageing Clock (BEAC) for estimating chronological age in avian species. BEAC was established based on genome-wide enzymatic methylation sequencing data of known-age king penguins (Aptenodytes patagonicus), and validated in nine other bird species. The BEAC collects age-informative signals into a bisulfite amplicon sequencing panel of 24 primer pairs, providing a highly accurate and cost-effective alternative to sequencing-intensive approaches. It achieved strong predictive performance in independent king penguin training (R{superscript 2}=0.88; MAE=1.7 years, n=78) and testing data (R{superscript 2}=0.79; MAE=2.3 years, n=41), with negligible batch effects, high longitudinal consistency, and resilience to reduced sample size or missing loci. Importantly, cross-species validation across 180 samples showed that BEAC reliably captures age-associated methylation signals in nine additional bird species across seven clades, demonstrating that a single set of loci can be predictive of ageing across multiple different bird species. BEAC offers a flexible, empirically validated tool and a transferable framework for developing epigenetic clocks in avian species, providing a highly valuable resource for eco-evolutionary studies of ageing in wild species.

molecular biology↗

bioRxiv2025

Common marmosets (Callithrix jacchus) do not differentiate between familiar and unfamiliar conspecifics based on pitch contour information

Previous studies suggest that vocal-learning species use variations of prosodic cues, such as changes in pitch, amplitude, or duration, in the conveying of meaning and emotions as well as individual recognition. Although it is known that the long-distance contact calls ("phee" calls) of common marmosets, a vocal non-learner, vary in prosodic information depending on individual characteristics, evidence of the species use of this information only recently started to emerge. In this study we tested 18 captive common marmosets (Callithrix jacchus) reactions to playbacks of familiar and unfamiliar individuals phee calls and extracted pitch-contour information. The playbacks consisted of i) natural phee calls from group members or unfamiliar conspecifics, or ii) synthesized pitch contours of familiar or unfamiliar phee calls following a natural or artificial syllable order as well as pure tones of similar frequency and duration. We found that although individuals seemed to show different reactions towards the natural calls of familiar and unfamiliar individuals, we did not find group level differences. Marmosets furthermore show significantly reduced interest in synthesized pitch contours compared to natural phee calls and did not differentiate between pitch contour playbacks and pure tone control stimuli, indicating that they did not categorize the pitch contours as conspecific calls. Our results suggest that extracted pitch contour information alone is not sufficient for marmosets to recognise conspecifics, however further studies are required to investigate the exact mechanism of individual recognition in marmosets.

animal behavior and cognition↗

bioRxiv2025

Associations between gut microbiota and personality traits: insights from a captive common marmoset (Callithrix jacchus) colony

Recent studies have suggested the link between inter-individual behavioural variation (i.e., animal personality) and gut microbiota. Non-human primates living under controlled conditions are valuable models to investigate diet-independent microbiome-host interactions. In this study, we investigated links between specific gut microbiota members and personality traits, as well as group membership, sex, age class, breeding status and relatedness of 26 captive common marmosets (Callithrix jacchus), maintained under the same diet and housing conditions. Personality was assessed using an established testing battery in repeated tests. Then, we collected a total of 225 fecal samples during the summers of 2017 and 2019 from five marmoset social groups for 16S rRNA gene amplicon sequencing. Within-individual microbiota variance was smaller than that between group members. Group members also exhibited more similar gut microbiota than individuals from different groups in each sampling year. Beta diversity of the gut microbiota was linked with personality traits, age class, sex, and breeding status, but not with genetic relatedness. We identified specific bacterial taxa associated with personality traits. In particular, members of the sulfite-reducing genera Desulfovibrio were enriched in more avoidant marmosets. Amplicon sequencing of the dissimilatory sulfite reductase gene dsrB confirmed this pattern, yet additionally revealed an unknown uncultured bacterium that was the predominant sulfite-reducing bacterium in the fecal samples and was linked to more explorative individuals. These findings highlight specific association patterns between selected microbial taxa and personality traits in captive common marmosets. ImportanceThis study provides valuable insights into the intricate relationship between gut microbiota and host personality traits, using captive common marmosets as a model. By controlling for diet and housing conditions, it probes key host factors such as personality, age, sex, and social group membership, offering a robust framework for understanding microbiome-host interactions. The discovery of specific microbial taxa associated with personality traits, particularly the enrichment of sulfite-reducing genera in more avoidant individuals, underscores the potential role of the gut microbiome in shaping or reflecting personality. These findings advance our understanding of microbiome-host dynamics and pave the way for future research on the mechanistic links between behavior and gut microbiota in other animal models and across broader ecological contexts.

microbiology↗

bioRxiv2023

Social attention across development in common ravens and carrion crows

Underlying social learning and other important aspects of successful adaptation to social life is social awareness, where individuals are required to pay attention and respond flexibly to others in their environment. We tested the influence of social context (alone, affiliate, non-affiliate, heterospecific) on behavioural interactions (manipulation, caching, head & body out of sight i.e. barrier use) with food and objects during development at fledging (1-2 months), juvenile (3-8 months) and sub-adult (14-18 months old) in 10 carrion crows (Corvus corone; C. cornix) and nine common ravens (C. corax). These species are closely related, generalist corvids and subjects were all hand-reared and housed in highly comparable conditions. Both species will routinely cache, i.e. hide food and other items for later recovery, and engage in cache-pilfering (stealing) strategies. They will interact and play with objects, potentially as part of developing social bonding and/or physical skills. We found that corvid behaviour was influenced by social context, with birds showing higher frequency of head & body out of sight behaviour while others were observing than when alone, suggesting they have an awareness of others presence and respond by using barriers when interacting with items. There were no differences based on observer identity, supporting an interpretation of item interaction and play potentially driving development of physical skills in this setting. There were developmental effects, including increased manipulation and use of barriers as juveniles as well as increased caching with age. Ravens generally cached more than crows. Objects were manipulated more frequently than food, while barriers were used more with food, indicating that food was more likely to be actively hidden while objects may promote open play. We discuss our findings in relation to other social and developmental influences on behaviour and the wider ramifications for identifying the drivers of play in animals.

animal behavior and cognition↗

bioRxiv2021

Individual repeatability, species differences, and the influence of socio-ecological factors on neophobia in 10 corvid species

Behavioural responses to novelty, including fear and subsequent avoidance of novel stimuli, behaviours referred to as neophobia, determine how animals interact with their environment. Neophobia aids in navigating risk and impacts on adaptability and survival. There is variation within and between individuals and species, however, lack of large-scale, comparative studies critically limits investigation of the socio-ecological drivers of neophobia. In this study, we tested responses to novel objects and food (alongside familiar food) versus a baseline (familiar food alone) in 10 corvid species (241 subjects) across 10 labs worldwide. There were species differences in the latency to touch familiar food in the novel object and food conditions relative to the baseline. Three of seven socio-ecological factors influenced object neophobia: 1) use of urban habitat (vs not), 2) territorial pair vs family group sociality and 3) large vs small flock size (whereas range, caching, hunting live animals, and genus did not); while only flock size influenced food neophobia. We found that, overall, individuals were temporally and contextually repeatable (i.e. consistent) in their novelty responses in all conditions, indicating neophobia is a stable behavioural trait. With this study, we have established a network of corvid researchers, demonstrating potential for further collaboration to explore the evolution of cognition in corvids and other bird species. These novel findings enable us, for the first time in corvids, to identify the socio-ecological correlates of neophobia and grant insight into specific elements that drive higher neophobic responses in this avian family group.

animal behavior and cognition↗