Biology subjects

Versace, E.

Publications and source records attributed to Versace, E..

At least 19 recordsLinked to original sources

bioRxiv2026

Programming of Embryonic Blood Brain Barrier and Neurovascular Transcriptome by an Anticipatory Acoustic Signal of Heat in the Zebra Finch

AbstractOrganisms have evolved mechanisms to adjust to rapid environmental change. A dramatic example is the Australian zebra finch, where incubating parents produce an acoustic signal ("heat call") during extreme heat, triggering adaptive phenotypic plasticity in their offspring growth, thermoregulation, and reproductive success. To elucidate for the first time the molecular mechanisms underlying heat call-induced programming, we hypothesized a prenatal shift in hypothalamic gene expression, given the hypothalamuss central role in neuroendocrine signaling controlling metabolism and growth. In addition, we tested whether prenatal heat-call exposure induces local changes in the brain, to protect this highly heat-sensitive organ from upcoming heat challenges. We exposed zebra finch embryos to chronic playback of parental heat calls or control calls, then isolated the hypothalamus for RNA sequencing to identify differentially expressed genes and gene regulatory networks. Heat-call exposure elicited modest neuroendocrine gene expression changes, but robust downregulation of genes tied to muscle contraction and cytoskeletal dynamics, with evidence of isoform usage shifts. These changes were prominently localized to hypothalamic neurovascular endothelial, mural, and ependymal cell populations, forming the blood-brain barrier (BBB). Because embryos experienced heat-associated sound, but not heat itself, and changes matched the loosening of the BBB to avoid breakages, these transcriptomic shifts likely represent an anticipatory response to enhance subsequent brain resilience to heat. Our study provides the first genome-wide characterization of embryonic hypothalamic gene expression in a songbird and reveals that prenatal acoustic cues can developmentally program neurovascular systems, expanding current understanding of developmental plasticity under climate change.

developmental biology↗

bioRxiv2025

Sex, not familiarity, shapes social interactions in adult tortoises (Testudo hermanni)

Social cohesion varies across species. Solitary animals minimise social contact to reduce costs such as resource competition, aggression, and disease transmission. Solitary Testudo hatchlings can rely on familiarity to avoid unfamiliar conspecifics. It remains unclear whether this strategy is used in adult captive tortoises and whether sex differences exist. To address these questions, we experimentally investigated a colony of captive Testudo hermanni tortoises (a vulnerable species), housed in outdoor enclosures. After a group familiarisation phase, we tested adult tortoises in a novel arena with either a familiar or an unfamiliar same-sex individual (not encountered for at least 3 months). Contrary to our expectations, familiarity had no significant effect on social cohesion measures such as inter-individual distance or facing orientation, showing that in adult captive tortoises familiarity had limited effect on social cohesion. In contrast, we found striking sex differences: males approached conspecifics quickly and remained in close proximity throughout the test, frequently displaying aggression; females initially explored the partner but then distanced themselves, with minimal aggression, similarly to what Testudo hatchlings have been observed to do with unfamiliar individuals. These results show that in adult captive tortoises adult social interactions and social cohesion are influenced by sex. This study provides insight into social cohesion and interaction strategies in tortoises, relevant for captive settings and conservation planning.

animal behavior and cognition↗

bioRxiv2025

Duration discrimination in the bumblebee Bombus terrestris

The ability to process temporal information is crucial for animal activities like foraging, mating, and predator avoidance. While circadian rhythms have been extensively studied, there is limited knowledge regarding how insects process durations in the range of seconds and sub-seconds. This study aimed to assess bumblebees (Bombus terrestris) ability to differentiate the durations of flashing lights, and use this information in a free-foraging task. Bees were trained to associate either the long or short-duration stimulus with a sugar reward versus an unpalatable solution until reaching a criterion, and then tested without sucrose solution with the same stimuli. In Experiment 1, we tested the ability to discriminate between a long stimulus (2.5 or 5 seconds) vs a short stimulus (0.5 or 1 second). The bees learned to discriminate between the two stimuli. To check whether bees solve the task without using the absolute difference in proximal stimulation as a cue, we ran a second experiment. In Experiment 2, the flashing stimuli were presented for the same total amount of time in a cycle. Bees could discriminate between durations even when the overall amount of stimulation in each presentation cycle was the same. This shows general learning abilities in bumblebees, that can discriminate seconds/subseconds intervals in visual flashing stimuli. This reveals an insects ability to use non-naturalistic stimuli and temporal cues in free foraging.

animal behavior and cognition↗

bioRxiv2025

Crossmodal pitch-luminance association in tortoises

If you think that high-pitched sounds match bright colours more than dark ones, you are not alone. Spontaneous associations between different sensory modalities --crossmodal associations-- are widely observed in humans. More recently, crossmodal associations have been reported in chimpanzees, monkeys, dogs, chickens, and tortoises, indicating a general cognitive strategy that reflects natural correlations in the environment or similarities in the architecture of the nervous system. Alternatively, or complementarily, crossmodal associations may arise from learning of species-specific occurrences. Recent research on primates has tentatively linked human pitch-luminance associations to the evolution of language. While humans and chimpanzees spontaneously match a high-pitched sound with a white shape and a low-pitched sound with a black shape, baboons and chickens do not exhibit any preferential association. Identifying spontaneous pitch-luminance associations in species that do not rely on vocal communication, such as the solitary Hermanns tortoises, would support the idea of a language-independent phenomenon. To test this idea, we studied tortoises for pitch-luminance associations in a spontaneous food-searching task. After hearing a high-pitched (700 Hz) vs low-pitched (450 Hz) sound, animals could choose to search for food behind either a light- or dark-coloured wall. When hearing the high-pitched sound, tortoises chose the white stimulus, whereas when hearing the low-pitched sound, they chose the black stimulus, similarly to what humans and chimpanzees do. These results demonstrate crossmodal pitch-luminance associations in tortoises. While showing this commonality in the perceptual organization of phylogenetically distant species, we shift the question on whether pitch-luminance associations reflect homology or convergent evolution.

animal behavior and cognition↗

bioRxiv2024

Noxious stimulation induces self-protective behaviour in bumblebees

Self-grooming directed towards a noxiously-stimulated body part is one indicator that an animal may feel pain. In insects, the lack of evidence for such behaviour has been widely argued to reflect the absence of pain experiences. Here, we tested whether bumblebees (Bombus terrestris) selectively groom one of their antennae that was touched with a noxiously-heated (65 {square}C) probe. In the first two minutes after being touched with the noxiously-heated probe, bees groomed their touched antenna a) more than their untouched antenna, b) more than bees that were touched on the antenna with an unheated probe, and c) more than control (untouched) bees groomed either of their antennae. Our results clearly show that bumblebees can direct grooming towards a site of noxious stimulation. Our findings thus refute arguments that claim that insects do not feel pain because of their lack of displaying this behaviour.

animal behavior and cognition↗

bioRxiv2023

Spontaneous biases enhance generalisation in the neonate brain

The ability to use sparse evidence to produce adaptive responses in new contexts and to new stimuli (inductive generalisation) is central to biological and artificial intelligence. Young and inexperienced animals require very little evidence to generalise, raising the question of whether the neonate brain is evolutionarily prepared (predisposed) for generalisation. To understand the principles of spontaneous generalisation, we exposed neonate chicks to an artificial social partner of a specific colour, and measured generalisation by comparing responses to novel and familiar stimuli along either the red-yellow or the blue-green colour continuum. Generalisation responses were inconsistent with an unbiased model, showing biases such as asymmetrical generalisation gradients, faster learning for particular colours (red and blue over yellow and green), preferences for unfamiliar stimuli and different time courses in learning. Moreover, the chicks generalisation behaviour was consistent with a Bayesian theoretical model that explicitly incorporates predispositions as initial preferences and treats the learning process as an update of spontaneous preferences. These results show that neonate animals are evolutionarily prepared for generalisation, via biases that do not depend on experience, reinforcement or supervision. Biases that facilitate generalisation are tuned to distinctive features that are unusual in the natural environment, such as the red and blue colours. Predispositions facilitate or hinder learning in the inexperienced brain, determining how experience is used to update the likelihood of predictive models. Neonate animals use spontaneous biases to solve the problem of induction.

neuroscience↗

bioRxiv2023

Assessing preferences for adult vs juvenile features in young animals: newly-hatched chicks spontaneously approach red and large stimuli

Young precocial birds benefit from staying close to both their mother and siblings, while prioritising adults, which provide better care. Which features of the stimuli are used by young birds to prioritise attachment to adults over siblings is unknown. We started to address this question in newly hatched domestic chicks (Gallus gallus), focusing on their spontaneous preferences for visual stimuli that systematically vary between adult and juvenile chickens: size (larger in adults than in juveniles) and colour (darker and redder in adults than in juveniles). Overall, chicks at their first visual experience, that had never seen a conspecific beforehand, were most attracted to the red and large stimuli (two adult features) and interacted with red stimuli more than with yellow stimuli. When tested with red large vs. small objects (Exp. 1), chicks preferred the large shape. When tested with yellow large and small objects (Exp. 2), chicks did not show a preference. These results suggest that the combination of size and colour form the predisposition that helps chicks to spontaneously discriminate between adult and juvenile features from the first stages of life, in the absence of previous experience.

animal behavior and cognition↗

bioRxiv2023

Pitch-size crossmodal correspondence in tortoises (Testudo hermanni)

Humans spontaneously match information coming from different senses, what we call crossmodal associations. For instance, high pitch sounds are preferentially associated with small objects, and low pitch sounds with larger ones. While previous studies reported crossmodal associations in mammalian species, evidence for other taxa is scarce, hindering an evolutionary understanding of this phenomenon. Here we provide evidence of pitch-size correspondence in a reptile, the tortoise Testudo hermanni. Tortoises showed a spontaneous preference to associate a small disc (i.e., visual information about size) to a high pitch sound (i.e., auditory information), and a larger disc to a low pitch sound. These results suggest that crossmodal associations may be an evolutionary ancient phenomenon, potentially an organising principle of the vertebrate brain.

animal behavior and cognition↗

bioRxiv2022

First-sight recognition of touched objects shows that chicks can solve the Molyneux's problem

If a congenitally blind person learns to distinguish between a cube and a sphere by touch, would they immediately recognise these objects by sight if their vision is restored? This question, posed by Molyneux in 1688, has puzzled philosophers and scientists. We overcame ethical and practical difficulties in the study of cross-modal recognition by using inexperienced chicks. We hatched chicks in darkness, exposed them to tactile smooth vs. bumpy stimuli in darkness and then tested them in a visual recognition task. At first sight, chicks previously exposed to smooth stimuli approached the smooth stimulus significantly more than those exposed to the bumpy stimuli. This shows that cross-modal recognition does not require multimodal experience. At least in precocial species, supra-modal brain areas already function at birth.

neuroscience↗

bioRxiv2022

Newborn chicks prefer stimuli that move against gravity

At the beginning of life, inexperienced animals use evolutionary-given preferences (predispositions) to decide what stimuli attend and approach. Stimuli that contain cues of animacy, such as face-like stimuli, biological motion and changes in speed, are particularly attractive across vertebrate taxa. A strong cue of animacy is upward movement against terrestrial gravity, because only animate objects consistently move upward. To test whether upward movement is spontaneously considered attractive already at birth, we tested the early preferences of dark-hatched chicks (Gallus gallus) for upward vs downward moving visual stimuli. We found that, without any previous visual experience, chicks consistently exhibited a preference to approach upward moving stimuli, that move against gravity. A control experiment showed that these preferences are not driven by avoidance of downward stimuli. These results show that newborn animals are spontaneously attracted by upward movement, indicating that movement against gravity can be used as a cue of animacy to orient early approach responses in the absence of previous visual experience.

animal behavior and cognition↗

bioRxiv2022

Motivational trade-offs in bumblebees

Mammals can supress their nociceptive responses to prioritise other important responses via endogenous modulation from the brain. It is well established that insects display nociception, but not whether the insect brain can modulate nociceptive processing. To address this question, we investigated whether bumblebees (Bombus terrestris) attraction to higher sucrose solution concentrations reduces their avoidance of noxious heat. Bees were given the choice between either unheated or noxiously-heated (55{degrees}C) feeders with different sucrose concentrations. The feeders were associated with colour stimuli to act as conditioned cues. Bees fed more from higher sucrose concentration heated feeders than lower sucrose concentration unheated feeders. Further, bees "testing out" of feeders (landing but not feeding) reduced as the experiment progressed, demonstrating that conditioned colour cues informed the bees behaviour. Therefore, bees trade off competing conditioned motivational stimuli to modulate nocifensive behaviour, suggesting a form of pain perception.

animal behavior and cognition↗

bioRxiv2021

Pre- and post-mating reproductive isolation evolve independently during rapid adaptation to high temperature

BackgroundEcological speciation and mutation-order speciation are two different mechanisms of adaptation-driven speciation. Both mechanisms predict different patterns of reproductive isolation for replicate populations adapting to the same environment. With ecological speciation, barriers to gene flow emerge between populations from different environments, but not among replicate populations from the same environment. Mutation-order speciation predicts reproductive isolation among populations adapted to the same environment. ResultsWe demonstrate that both speciation processes occurred within about 100 generations when replicate Drosophila simulans populations adapted to a novel, hot environment. Gene expression analysis identified the underlying molecular mechanisms. Premating ecological speciation is the byproduct of an altered lipid metabolism, which also changed the cuticular hydrocarbon (CHC) composition in hot-evolved flies. Postmating reproductive isolation supports mutation-order speciation most likely driven by co-evolution of reproduction-associated genes. ConclusionAdaptation processes can rapidly induce incipient speciation and different speciation mechanisms affect pre- and postmating reproductive isolation. We propose that the definition of mutation-order speciation should be expanded to account for polygenic processes from standing genetic variation.

evolutionary biology↗

bioRxiv2021

Light-induced asymmetries in the embryonic retina are mediated by the vascular system and extracellular matrix

Left-right asymmetries in the nervous system (lateralisation) influence a broad range of behaviours, from social responses to navigation and language. The role and pathways of endogenous and environmental mechanisms in the ontogeny of lateralisation remains to be established. The domestic chick is a model of both endogenous and experience-induced lateralisation driven by light exposure. Following the endogenous rightward rotation of the embryo, the asymmetrical position in the egg results in a greater exposure of the right eye to environmental light. To identify the genetic pathways activated by asymmetric light stimulation, and their time course, we exposed embryos to different light regimes: darkness, 6 hours of light and 24 hours of light. We used RNA-seq to compare gene expression in the right and left retinas and telencephalon. As expected, no differential expression between left and right was present in darkness. We detected differential gene expression in right vs left retina after 6 hours of light exposure. This difference disappeared before 24 hours of light exposure, suggesting that light-induced activation is a self-terminating phenomenon. This transient effect of light exposure was associated with a downregulation of the sensitive-period mediator gene DIO2 (iodothyronine deiodinase 2) in the right retina. No differences between genes expressed in the right vs. left telencephalon were detected. Gene networks associated with lateralisation were connected to vascularisation, cell motility, and the extracellular matrix. Interestingly, we know that the extracellular matrix- including the differentially expressed PDGFRB (platelet-derived growth factor receptor {beta}) gene - is involved in both sensitive periods and in the endogenous chiral mechanism of primary cilia, that drives lateralisation. Our data show a similarity between endogenous and experience-driven lateralisation, identifying functional gene networks that affect lateralisation in a specific time window.

neuroscience↗

bioRxiv2021

Visual Field Analysis: a reliable method to score left- and right eye-use using automated tracking

Brain and behavioural asymmetries have been documented in various taxa. Many of these asymmetries involve preferential left- and right-eye use. However, measuring eye use through manual frame-by-frame analyses from video recordings is laborious and may lead to biases. Recent progress in technology allowed the development of accurate tracking techniques for measuring animal behaviour. Amongst these techniques, DeepLabCut, a python-based tracking toolbox using transfer learning with deep neural networks, offers the possibility to track different body parts with unprecedented accuracy. Exploiting the potentialities of DeepLabCut, we developed Visual Field Analysis, an additional open-source application for extracting eye-use data. To our knowledge, this is the first application that can automatically quantify left-right preferences in eye use. Here we test the performance of our application in measuring preferential eye-use in young domestic chicks. The comparison with manual scoring methods revealed a perfect correlation in the measures of eye-use obtained by Visual Field Analysis. With our application, eye-use can be analysed reliably, objectively and at a fine scale in different experimental paradigms.

animal behavior and cognition↗

bioRxiv2021

Recognition of familiar objects in tortoise hatchlings (Testudo spp.)

Tortoises do not show parental care and live solitary except for the context of reproduction. Despite their limited need to interact with conspecifics, we previously observed that young tortoises, at their first experiences with conspecifics, can discriminate between familiar and unfamiliar conspecifics after just one encounter with another tortoise. Tortoise hatchlings ignored familiar conspecifics, while they first explored and then actively avoided unfamiliar conspecifics. It remains to be established whether the different reactions to unfamiliar and familiar individuals in tortoise hatchlings are reactions to novelty, or whether they are specific to the interactions with living animals. To test this, we familiarized one-month-old tortoise hatchlings with an object (a brown cone vs. a blue sphere) and then tested them in a novel arena once with the familiar object and once with an unfamiliar one. To measure the reactions toward familiar and unfamiliar objects, we measured the distance between the tortoise and the object throughout the test. Differently from what happened with unfamiliar and familiar conspecifics, we found no difference in behavior toward familiar and unfamiliar objects. This shows that the different reactions toward familiar and unfamiliar conspecifics previously observed are specific for social interactions and are not a mere reaction to the novelty effect. The behavioral responses displayed by young tortoises for unfamiliar conspecifics, but not for unfamiliar objects, show the relevance of social behavior from the beginning of life, even for solitary species.

animal behavior and cognition↗

bioRxiv2021

Young domestic chicks spontaneously represent the absence of objects

Absence is a notion that is usually captured by language-related concepts like zero or negation. Whether non-linguistic creatures encode similar thoughts is an open question, as everyday behavior marked by absence (of food, of social partners) can be explained solely by expecting presence somewhere else. We investigated 8-day-old chicks looking behavior in response to events violating expectations about the presence or absence of an object. We found different behavioral responses to violations of presence and absence, suggesting distinct underlying mechanisms. Importantly, chicks displayed an avian signature of novelty detection to violations of absence, namely a sex-dependent left-eye-bias. Follow-up experiments excluded accounts that would explain this bias by perceptual mismatch or by representing the object at different locations. These results suggest that the ability to spontaneously form thoughts about the absence of objects likely belongs to the initial cognitive repertoire of vertebrate species.

animal behavior and cognition↗

bioRxiv2020

Resurgence of a perinatal attraction for animate objects via thyroid hormone T3

For inexperienced brains, some stimuli are more attractive than others. Human neonates and newly-hatched chicks preferentially orient towards face-like stimuli, biological motion, and objects changing speed. In chicks, this enhances exposure to social partners, and subsequent attachment trough filial imprinting. Early preferences are not steady. The preference for stimuli changing speed fades away after three days in chicks. To understand the physiological mechanisms underlying these transient responses, we tested whether the early preferences for objects changing speed can be promoted by thyroid hormone 3,5,3-triiodothyronine (T3). This hormone determines the start of imprintings sensitive period. We found that the preference for objects changing speed can be re-established in female chicks treated with T3. Moreover, day-one chicks treated with an inhibitor of endogenous T3 did not show any preference. These results suggest that the time windows of early predispositions and of high plasticity are controlled by the same molecular mechanisms.

animal behavior and cognition↗

bioRxiv2020

Young chicks quickly lose their spontaneous preference to aggregate with females

It is not clear when and how animals start to discriminate between male and female conspecifics and how this distinction drives their social behaviour. A recent study on pheasants found that one-week-old chicks (Phasianus colchicus) preferentially aggregated with same-sex peers and this trend became more pronounced through development, suggesting that sexual segregation increases during ontogeny. However, it remains unclear whether this ability depends on experience or develops spontaneously. Using a similar experimental protocol, we investigated whether sex discrimination is present at birth in domestic chickens (Gallus gallus) by testing the aggregation preferences of young chicks with clutch mates. We measured the amount of time spent close to male and female conspecifics in visually inexperienced chicks. Soon after hatching, both males and females preferentially aggregated with females. To clarify whether the experience with conspecifics modifies the initial preference for females we used an imprinting procedure. We exposed chicks to conspecifics of the same sex, different sex or both sexes for three days and then tested their preferences to aggregate with males or females. No sex preference was observed after three days of imprinting exposure. The disappearance of the initial sex preference shows that, although chicks can discriminate between conspecifics of different sex, sex segregation does not influence aggregation in the first week of life. We suggest that the absence of sexual assortment in the first week of age can enhance the social cohesion of the flock.

animal behavior and cognition↗