Biology subjects

Triki, Z.

Publications and source records attributed to Triki, Z..

11 recordsLinked to original sources

bioRxiv2026

Big-team science reveals that patterns of inhibitory control variation in teleost fishes differ from those in mammals and birds

Understanding the evolution of cognition is fundamental to understanding the origins and nature of our own cognitive abilities, with cross-species comparisons providing a cornerstone of this endeavor. Yet, comparative cognition so far has largely focused on endothermic vertebrates, particularly mammals and birds, while ectotherms--representing a substantial proportion of vertebrate diversity--remain relatively understudied. Moreover, variation in experimental methods makes existing data difficult to compare across species. Big-team science offers a way to overcome these limitations by enabling standardized cognitive testing across broad taxonomic scales. Here, we apply this approach to fishes, using inhibitory control as a proof of concept for standardized comparative testing in 444 individuals across 22 teleost species spanning 19 genera. We demonstrate that standardized cognitive testing across such diversity is feasible, while also revealing substantial heterogeneity in the sample. Performance varied markedly among species, but, strikingly, showed only a weak phylogenetic signal, contrasting with patterns previously reported in mammals and birds. In addition, we detected great within-species variation, including differences across research groups, suggesting that performance may reflect not only species-level evolutionary history but also ontogenetic experience and the capacity to adjust decision rules to local conditions. Together, our findings highlight the importance of both evolutionary and environmental sources of cognitive variation and demonstrate that extending standardized comparative approaches beyond traditionally studied endotherms can reveal a more dynamic and complex picture of cognitive evolution across the vertebrate lineage.

animal behavior and cognition↗

bioRxiv2025

Endothelial Function: A Novel Marker to Evaluate the Prognosis of Heart Failure with Reduced Ejection Fraction

BackgroundEndothelial function, a key determinant of prognosis in heart failure with reduced ejection fraction (HFrEF), is still frequently under-assessed in clinical practice. The present study aimed to assess endothelial function in patients with HFrEF and investigate its association with echography and hemodynamics over a 3-month medical treatment. Additionally, this study aimed to investigate the association between changes in endothelial function and the incidence of cardiovascular rehospitalizations or deaths. MethodsThis prospective longitudinal study included 120 patients with HFrEF. Hemodynamic parameters were assessed using impedance cardiography. Endothelial function was evaluated using digital thermal monitoring to calculate the Endothelial Quality Index (EQI) at baseline and after 3 months. Patients were followed for 12 months. ResultsThe mean age was 61.9 {+/-} 10.2 years, with a sex ratio of 5:1. 42.5% of patients tend to experience endothelial dysfunction at baseline. After 3 months of optimized therapy, EQI improved significantly (p<0.001), correlating with improved echography and hemodynamic parameters. Over 12 months, there were 5 deaths (4.16%) and 44 heart failure rehospitalizations (36.6%), predominantly among those with severe endothelial dysfunction (p=0.008). Improved EQI was associated with reduced mortality (AUC = 0.82) and rehospitalization risk (AUC = 0.837). A {Delta}EQI [≥] 0.2 predicted better prognosis (HR: 0.157, 95% CI: 0.054-0.454, p=0.001). ConclusionPatients with HFrEF exhibited endothelial dysfunction. The improvement in endothelial function after an optimized treatment is associated with an enhancement in echography and hemodynamic parameters. Additionally, endothelial function was a strong prognostic marker.

physiology↗

bioRxiv2024

Brain virtual histology of a lizard species (Podarcis bocagei) using X-ray micro-tomography and deep-learning segmentation

Lately, there has been an emphasis on the importance of studying inter-individual variation in animal behaviour and cognition and understanding its underlying mechanisms. What was once considered mere noise around population mean can be explained by individual characteristics such as brain morphology and functionality. However, logistical limitations can be faced when studying the brain, especially for research involving wild animals, such as dealing with small sample sizes and time-consuming methods. Here, we combined an efficient and accurate method using X-ray micro-tomography and deep-learning (DL) segmentation to estimate the volume of six main brain areas of wild lizards, Podarcis bocagei: olfactory bulbs, telencephalon, diencephalon, midbrain, cerebellum and brain stem. Through quantitative comparison, we show that a sufficient deep-learning neural network can be trained with as few as five data sets. From this, we applied the trained deep-learning algorithm to obtain volume data of the six brain regions from 29 brains of Podarcis bocagei. We provide a detailed protocol for our methods, including sample preparation, X-ray tomography, and 3D volumetric segmentation. Our work is open-access and freely available, with the potential to benefit researchers in various fields, such as animal physiology, biomedical studies, and computer sciences.

zoology↗

bioRxiv2024

Oxytocin and shared intentionality drive variation in cooperation in children

While humans cooperate with unrelated individuals to an extent that far outstrips any other species, we also display extreme variation in decisions about whether to cooperate or not. A diversity of cognitive, affective, social, and physiological mechanisms interact to shape these decisions. For example, group membership, shared intentionality talk (i.e. talk about shared goals), and natural initial oxytocin levels affect cooperation in adults in an optimal foraging paradigm that is loosely modelled on the iterated prisoners dilemma. In this egg hunt, shared intentionality talk was key to achieve cooperation, and it occurred more between participants who shared the same group membership and had higher initial oxytocin levels. Such complex interactions raise the question of the age at which humans develop the necessary mechanisms to cooperate effectively in the egg hunt game. Here, we tested children in secondary school aged between 10 and 14 years. We found that, as for adults, shared intentionality talk was crucial for successful cooperation. Furthermore, initial oxytocin levels affected cooperation through shared intentionality talk. In contrast, group membership did not affect behaviour. Finally, pre- and post-experiment oxytocin levels showed various interactions with group membership and gender. Thus, childrens performance was relatively similar to adults while showing some differences with respect to underlying mechanisms. Our study is a rare contribution to further our understanding of the role of oxytocin in early adolescent social behaviour.

developmental biology↗

bioRxiv2024

Coral reef fish resilience and recovery following major environmental disturbances caused by cyclones and coral bleaching: A case study at Lizard Island

Coral reef fish communities can be affected by natural disturbances such as cyclones and coral bleaching. It is not yet understood how long it takes these communities to recover from such extreme events, particularly when they occur repeatedly. To investigate this, we conducted fish surveys repeatedly between 2011 and 2022 at Lizard Island on the Great Barrier Reef in Australia. We focused on two reef sites, Mermaid Cove and Northern Horseshoe, both of which were damaged by a large-scale coral bleaching event in 2016 and 2017, as well as two cyclones that occurred in 2014 and 2015 (the cyclones hit Mermaid Cove but not Northern Horseshoe). Between 2016 and 2017, both reef sites saw a decrease in the total fish abundance of about 68 % and across most functional groups (carnivores, corallivores, herbivores, and omnivores). Despite the two sites showing different decline and recovery patterns, they both showed an improvement in fish abundance and across the majority of functional groups at both sites by 2022. The recovery reached similar numbers as those documented in the fish census data collected before the disturbances occurred. Our findings provide a case study highlighting how fish community resilience can vary on small local scales, with potential recovery if conditions are favourable over several years.

zoology↗

bioRxiv2023

Social complexity affects cognitive abilities but not brain structure in a Poecilid fish

Complex cognitive performance is suggested to be the out-turn of complex social life, allowing individuals to achieve higher fitness through sophisticated "Machiavellian" strategies. Although there is ample support for this concept, especially when comparing species, most of the evidence is correlative. Here we provide an experimental investigation of how group size and composition may affect brain and cognitive development in the guppy (Poecilia reticulata). For six months, we reared sexually mature female guppies in one of three different social treatments: (i) three female guppies; (ii) three female guppies mixed with three female splash tetras (Copella arnoldi), a species that co-occurs with the guppy in the wild; and (iii) six female guppies. We then tested the guppies performance in inhibitory control, associative learning and reversal learning tasks to evaluate their self-control, operant conditioning and cognitive flexibility capabilities. Afterwards, we estimated their brain size and the size of major brain regions using X-ray imaging technology. We found that individuals in larger groups of six individuals, in both same and mixed species treatments, outperformed individuals from the smaller groups of three guppies in reversal learning, with no apparent differences in the inhibitory control and associative learning tasks. This is rare evidence of how living in larger social groups improves cognitive flexibility, supporting that social pressures play an important role in shaping individual cognitive development. Interestingly, social manipulation had no apparent effect on brain morphology, but relatively larger telencephalons were associated with better individual performance in reversal learning. This suggests alternative mechanisms beyond brain region size enabled greater cognitive flexibility in individuals from larger groups.

animal behavior and cognition↗

bioRxiv2023

Serotonin blocker Ketanserin reduces coral reef fish Ctenochaetus striatus aggressive behaviour during between-species social interactions

A multitude of species engages in social interactions not only with their conspecifics but also with other species. Such interspecific interactions can be either positive, like helping, or negative, like aggressive behaviour. However, the physiological mechanisms of these behaviours remain unclear. Here, we manipulated the serotonin system, a well-known neurohormone for regulating intraspecific aggressive behaviour, to investigate its role in interspecific aggression. We tested whether serotonin blockade affects the aggressive behaviour of a coral reef fish species (Ctenochaetus striatus) that engages in mutualistic interactions with another species, the cleaner fish (Labroides dimidiatus). Although this mutualistic cleaning relationship may appear positive, cleaner fish do not always cooperate and remove ectoparasites from the other coral reef fish ("clients") but tend to cheat and bite the clients protective layer of mucus. Client fish thus often apply control mechanisms, like chasing, to deter their cleaner fish partners from cheating. Our findings show that blocking serotonin receptors 5-HT2A and 5-HT2C with ketanserin reduced the client fishs aggressive behaviour towards cleaner fish, but in the context where the latter did not cheat. These results are evidence of the involvement of serotonin in regulating aggressive behaviour at the between-species social interactions level. Yet, the direction of effect we found here is the opposite of previous findings using a similar experimental set-up and ecological context but with a different client fish species (Scolopsis bilineatus). Together, it suggests that serotonins role in aggressive behaviour is complex, and at least in this mutualistic ecological context, the function is species-dependent. This warrants, to some extent, careful interpretations from single-species studies looking into the physiological mechanisms of social behaviour.

animal behavior and cognition↗

bioRxiv2022

Field and experimental data together with computational models reveal how cleaner fish adjust decisions in a biological market

While it is generally straightforward to quantify individual performance in cognitive experiments, identifying the underlying cognitive processes remains a major challenge. Often, different mechanistic underpinnings yield similar performances, and Lloyd Morgans cannon warrants acceptance of the simpler explanation. Alternatively, when the different mechanisms interact with environmental conditions, variation in performance across environments might allow to statistically infer the mechanism responsible. We illustrate this point by fitting computational models to experimental data on performance by wild-caught cleaner fish Labroides dimidiatus in an ephemeral reward task, as well as cleaner and client fish densities from the locations of capture. Using Bayesian statistics to fit the model parameters to performance data revealed that cleaner fish most likely estimate future consequences of an action, while it appears unlikely that the removal of the ephemeral reward acts as psychological punishment (negative reinforcement). Incorporating future consequences also yields performances that can be considered the result of locally optimal decision-rules, in contrast to the negative reinforcement mechanism. We argue that the combination of computational models with data is a powerful tool to infer the mechanistic underpinnings of cognitive performance. Author summaryPerformance in behavioural experiments is often used to assess the cognitive abilities of animals. However, animals can get to the same outcome in alternative ways. Thus, the outcome of the experiments does not tell us how animals achieve their performance. In order to overcome this limitation, we used a set of computational models, which provide predictions on how alternative cognitive mechanisms perform in the face of varying environmental conditions, and compare their predictions to performance data from individuals that experienced different conditions throughout their life. Our study system is the cleaner fish Labroides dimidiatus, a coral reef fish that feeds off ectoparasites and dead tissue from the skin of other reef fishes. Cleaner fish often have to choose among alternative clients seeking their cleaning service, and the optimal choice is often hard to achieve. Our performance experiments mimic the natural choices the cleaner fish make. The combination of experiments and computational models points to cleaner fish abilities to account for the future effect of their choices by estimating the long term expected value of those choices. Estimating long term value is a mechanism involved in human foresight.

animal behavior and cognition↗

bioRxiv2021

Artificial mosaic brain evolution of relative telencephalon size improves cognitive performance in the guppy (Poecilia reticulata)

The telencephalon is a brain region believed to have played an essential role during cognitive evolution in vertebrates. However, till now, all the evidence on the evolutionary association between telencephalon size and cognition stem from comparative studies. To experimentally investigate the potential evolutionary association between cognitive abilities and telencephalon size, we used male guppies artificially selected for large and small telencephalon relative to the rest of the brain. In a detour task, we tested a functionally important aspect of executive cognitive ability; inhibitory control abilities. We found that males with larger telencephalon outperformed males with smaller telencephalon. They showed faster improvement in performance during detour training and were more successful in reaching the food reward without touching the transparent barrier. Together, our findings provide the first experimental evidence showing that evolutionary enlargements of relative telencephalon size confer cognitive benefits, supporting an important role for mosaic brain evolution during cognitive evolution.

ecology↗

bioRxiv2021

A farewell to EQ: A new brain size measure for comparative primate cognition

Both absolute and relative brain size vary greatly among and within the major vertebrate lineages. Scientists have long debated how larger brains in primates and hominins translate into greater cognitive performance, and in particular how to control for the relationship between the non-cognitive functions of the brain and body size. One solution to this problem is to establish the slope of cognitive equivalence, that is the line connecting organisms with an identical bauplan but different body sizes. Here, we suggest that intraspecific slopes provide the best available estimate of this measure. This approach was abandoned because slopes were too low by an unknown margin due to estimation error. We control for the error problem by focusing on highly dimorphic primate species with large sample sizes and fitting a line through the mean values for adult females and males. We obtain the best estimate for the slope of ca 0.27, a value much lower than those constructed using all mammal species, and close to the value expected based on the genetic correlation between brain size and body size. We also find that the estimate of cognitive brain size based on cognitive equivalence fits empirical cognitive studies better than the encephalization quotient (EQ), which should therefore be avoided in future studies on primates, and presumably mammals and birds in general. The use of residuals from the line of cognitive equivalence may change conclusions concerning the cognitive abilities of extant and extinct primate species, including hominins.

animal behavior and cognition↗

bioRxiv2021

Relative brain size and cognitive equivalence in fishes

There are two well-established facts about vertebrate brains: brains are physiologically costly organs, and both absolute and relative brain size varies greatly between and within the major vertebrate clades. While the costs are relatively clear, scientists struggle to establish how larger brains translate into higher cognitive performance. Part of the challenge is that intuitively larger brains are needed to control larger bodies without any changes in cognitive performance. Therefore, body size needs to be controlled to establish the slope of cognitive equivalence between animals of different sizes. Potentially, intraspecific slopes provide the best available estimate of how an increase in body size translates into an increase in brain size without changes in cognitive performance. Here, we provide the first evaluation of this hypothesis for fishes. First, a dataset of 51 species that included only samples of [≥] ten wild-caught individuals yielded a mean brain-body slope of 0.46 (albeit with a large range of 0.26 to 0.79). This mean slope is similar to the encephalisation quotients for ectotherm higher taxa, i.e. teleost fishes, amphibians and reptiles ([~] 0.5). However, the slope is much higher than what has been found in endotherm vertebrate species ([~] 0.3). Second, we provide slope estimates for brain-body sizes and for cognition-body sizes in wild-caught cleaner fish Labroides dimidiatus as a case study. Brain-body slopes from two datasets gave the values of 0.58 (MRI scans data) and 0.47 (dissection data). Furthermore, we have cognitive performance data from 69 individuals tested in four different cognitive tasks that estimated learning, numerical, and inhibitory control abilities. In all four tasks, the cognitive performance did not correlate significantly with body size. These results suggest that the brain-body slopes represent estimates of intraspecific cognitive equivalence for this species. While subject to further studies on various species, our results suggest that endo- and ectotherm brain organisations and resulting cognitive performances are fundamentally different.

animal behavior and cognition↗