Biology subjects

Papageorgiou, D.

Publications and source records attributed to Papageorgiou, D..

9 recordsLinked to original sources

bioRxiv2025

Space use fidelity of non-territorial vulturine guineafowl groups is shaped by both environmental and social processes

Animals often use consistent areas. Some are territorial, restricting their space use within territorial boundaries, whereas others at not territorial animals but still restrict their space use despite not being constrained by surrounding conspecifics. Staying within a familiar area can provide a range of benefits, such as using previous knowledge (i.e. memory) to efficiently exploit resources or because they can consistently return to key locations (such as a nest or sleeping site). In group-living animals, consistent space use could reduce the complexity of decision-making time (e.g. by choosing among known foraging sites), facilitating group cohesion. However, to date, little research has explicitly asked what factors determine whether groups use consistent areas. Here we used repeated movements by groups of vulturine guineafowl (Acryllium vulturinum)--leaving and returning back to the same areas in response to seasonal conditions--to examine and disentangle social processes from spatial and ecological factors that might shape the distribution of animals over space. Specifically, we quantified (i) how groups distribute themselves over the landscape, (ii) if their space use is consistent across seasons with similar environmental conditions, (iii) how different social and spatial factors shape the consistency of space use by groups over time, and (iv) how social and spatial factors affect home range overlap between groups. We found that groups were highly consistent in their space use over time and that home ranges were distinct across groups. Fidelity to the core home range area was higher when group composition was more stable, while overall home range fidelity was higher when groups recently experienced milder ecological conditions. Overlap in core areas and the overall home ranges among groups were greater among groups that shared roosts and groups that were fused in the previous season. Home range overlap was also lowest during long intermediate seasons (i.e. a sampling period that immediately follows intermediate season conditions, as opposed to sampling periods that followed dry or wet conditions), suggesting that extended intermediate conditions allow groups to increasingly partition their overall space use. These results provide insights into how the movement decisions by groups, the distribution of animals, and group-level space use emerge, and the role of social and ecological conditions as potential precursors to territoriality.

ecology↗

bioRxiv2025

Group size influences behavioral plasticity in responses to thermoregulation-foraging trade-offs by a socially cohesive bird

Behavioral plasticity, such as changes in habitat use and activity, can be a critical modulator of thermal pressures on endotherms. However, shifts in behaviors can meet diversified costs such as missed feeding opportunities. Individual decision-making should therefore capture the trade-off between the costs and the benefits of thermoregulation. In the case of social species, the decision process could also be facilitated or slowed down by the modulation of costs arising through the social environment. In this study, we tested how vulturine guineafowl (Acryllium vulturinum) change their use of open areas (where they predominately forage) according to heat using GPS data from 105 birds collected every 5 minutes for 6 months. Because animals vary in their sensitivity to risk according to group size--e.g. due to the dilution effect--we compared the responses of individuals depending on the size of the group they belong to. We also analyzed if behavioral responses translate into less precise thermoregulation by recording the body temperature of a subset of birds in two groups. We foundd that birds avoid heat by selectively using open areas and moving to cover, as well as reducing activity when temperature increases, birds use open areas less and move less. Individuals from intermediate-sized groups seemed to be able to use open areas during warmer conditions compared to individuals from small and large groups (10% higher probability of use). However, active birds in the open did not present hyperthermia, suggesting that behavioral changes are efficient or that individuals have other efficient strategies such as physiological cooling. Together, these results indicated that responses to high temperatures are complex, as they included not only a range of environmental constraints but that responses can also vary according to social context.

ecology↗

bioRxiv2022

Cooperative breeding in a plural breeder: the vulturine guineafowl (Acryllium vulturinum)

Cooperative breeding is widely reported across the animal kingdom. In birds, it is hypothesised to be most common in altricial species (where chicks are dependent on parental care in the nest after hatching), with few described cases in precocial species (where chicks are more independent immediately after hatching). However, cooperative breeding may also be more difficult to detect in precocial species and therefore has been overlooked. In this study, we investigate whether vulturine guineafowl (Acryllium vulturinum)--which have precocial young--breed cooperatively and, if so, how care is distributed among group members. Using data collected from colour-banded individuals in one social group of vulturine guineafowl over three different breeding seasons, we found that multiple females can attempt to reproduce in the same breeding season. Broods had close adult associates, and most of these associates exhibited four distinct cooperative breeding behaviours: babysitting, within-group chick guarding, covering the chicks under the wings and calling the chicks to food. Further, we found that offspring care is significantly male-biased, that non-mother individuals provided most of the care each brood received, that breeding females differed in how much help they received, and that carers pay a foraging cost when providing care. Our results confirm that vulturine guineafowl are cooperative breeders, which they combine with an unusual plural-breeding social system. Our study also adds to growing evidence that cooperative breeding may be more widespread among species with precocial young than previously thought, thereby providing a counterpoint to the altriciality-cooperative breeding hypothesis.

animal behavior and cognition↗

bioRxiv2022

Beyond the dyad: uncovering higher-order structure within cohesive animal groups

Revealing the consequences of social structure in animal societies is largely determined by our ability to accurately estimate functionally relevant patterns of social contact among individuals. Of particular relevance are social contacts that drive and maintain the cohesion of moving animal groups. To date, studies have predominantly built up social structure from dyadic connections, which while effective in open societies--where groups are ephemeral--may not be sufficient to characterise the fine-grained structure within more cohesive animal groups. This is because associations or interactions can involve more than two individuals participating together, which current approaches cannot distinguish from independent sets of dyadic connections. Here we apply higher-order temporal network approaches to high-resolution GPS data from every group member in two cohesive groups of vulturine guineafowl (Acryllium vulturinum). By quantifying moment-by-moment association dynamics, we reveal clear sex-biased contributions to the group cohesion. Specifically, males form the cohesive core of the group as they participate in temporally consistent sub-groups and tend to occupy forward positions when in movement. Females instead remain peripheral and are more likely to leave sub-groups, while also occupying rear positions in moving sub-groups. These results reveal how the cohesion among males, which were previously found to be more likely to lead group movements, allows them to more often form a majority, confirming that self-organisation within the group can drive leadership patterns independently of dominance. Our study thus demonstrates that sub-group association dynamics derived from high-resolution GPS data can provide insights in how the fine-scale spatial and social organisation of cohesive groups, and their temporal dynamics, can explain key processes like leadership.

animal behavior and cognition↗

bioRxiv2022

A guide to using GPS-based tracking to study animal societies

GPS-based tracking is widely used for studying wild social animals. Much like traditional observational methods, using GPS devices requires making a number of decisions about sampling that can affect the robustness of a studys conclusions. For example, sampling fewer individuals per group across more distinct social groups may not be sufficient to infer group- or subgroup-level behaviours, while sampling more individuals per group across fewer groups limits the ability to draw conclusions about populations. Here, we provide quantitative recommendations when designing GPS-based tracking studies of animal societies. We focus on the trade-offs between three fundamental axes of sampling effort: 1) sampling coverage--the number and allocation of GPS devices among individuals in one or more social groups; 2) sampling duration--the total amount of time over which devices collect data; 3) sampling frequency--the temporal resolution at which GPS devices record data. We first test GPS tags under field conditions to quantify how these aspects of sampling design can affect both GPS accuracy (error in absolute positional estimates) and GPS precision (error in the estimate relative position of two individuals), demonstrating that GPS error can have profound effects when inferring distances between individuals. We then use data from whole-group tracked vulturine guineafowl (Acryllium vulturinum) to demonstrate how the trade-off between sampling frequency and sampling duration can impact inferences of social interactions and to quantify how sampling coverage can affect common measures of social behaviour in animal groups, identifying which types of measures are more or less robust to lower coverage of individuals. Finally, we use data-informed simulations to extend insights across groups of different sizes and cohesiveness. Based on our results, we are able to offer a range of recommendations on GPS sampling strategies to address research questions across social organizational scales and social systems--from group movement to social network structure and collective decision-making. Our study provides practical advice for empiricists to navigate their decision-making processes when designing GPS-based field studies of animal social behaviours, and highlights the importance of identifying the optimal deployment decisions for drawing informative and robust conclusions.

animal behavior and cognition↗

bioRxiv2022

The Layer 7 Cortical Interface: A Scalable and Minimally Invasive Brain-Computer Interface Platform

Progress toward the development of brain-computer interfaces has signaled the potential to restore, replace, and augment lost or impaired neurological function in a variety of disease states. Existing approaches to developing high-bandwidth brain-computer interfaces rely on invasive surgical procedures or brain-penetrating electrodes, which limit addressable applications of the technology and the number of eligible patients. Here we describe a novel approach to constructing a neural interface, comprising conformable thin-film electrode arrays and a minimally invasive surgical delivery system that together facilitate bidirectional communication with large portions of the cortical surface (enabling both recording and stimulation). We demonstrate the feasibility and safety of delivering reversible implants containing over 2,000 microelectrodes to multiple functional regions in both hemispheres of the brain simultaneously, without requiring a craniotomy or damaging the cortical surface, at an effective insertion rate faster than 40 ms per channel. We further evaluate the performance of this system immediately following implantation for high-density neural recording and visualizing cortical surface activity at spatial and temporal resolutions and extents not previously possible in multiple preclinical large animal studies as well as in a five-patient pilot clinical study involving both anesthetized and awake neurosurgical patients. We characterize the spatial scales at which sensorimotor activity and speech are represented at the cortical surface, demonstrate accurate neural decoding of somatosensory, visual, and volitional walking activity, and achieve precise neuromodulation through cortical stimulation at sub-millimeter scales. The resulting system generates 90 Gb/h of electrophysiologic data, and demonstrates the highly scalable nature of micro-electrocorticography and its utility for next-generation brain-computer interfaces that may expand the patient population that could benefit from neural interface technology.

neuroscience↗

bioRxiv2021

DEAD-box RNA Helicases Act as Nucleotide Exchange Factors for Casein Kinase 2

DDX RNA helicases promote RNA processing but DDX3X is also known to activate casein kinase 1 {varepsilon} (CK1{varepsilon}). Here we show that not only is protein kinase stimulation a latent property of other DDX proteins towards CK1{varepsilon}, but that this extends to casein kinase 2 (CK22) as well. CK22 enzymatic activity is stimulated by a variety of DDX proteins and we identify DDX1/24/41/54 as physiological activators required for full kinase activity in vitro and in Xenopus embryos. Mutational analysis of DDX3X reveals that CK1 and CK2 kinase stimulation engages its RNA binding-but not catalytic motifs. Mathematical modelling of enzyme kinetics and stopped-flow spectroscopy converge that DDX proteins function as nucleotide exchange factor towards CK22 that reduce unproductive reaction intermediates and substrate inhibition. Our study reveals protein kinase stimulation by nucleotide exchange as a new principle in kinase regulation and an evolved function of DDX proteins.

biochemistry↗

bioRxiv2021

Costs dictate strategic investment in dominance interactions

Dominance is important for access to resources. As dominance interactions are costly, individuals should be strategic in who they interact with. One hypothesis is that individuals should direct costly interactions towards those closest in rank, as they have most to gain--in terms of attaining or maintaining dominance--from winning such interactions. Here, we show that male vulturine guineafowl (Acryllium vulturinum), a gregarious species with steep dominance hierarchies, strategically express higher-cost aggressive interactions towards males occupying ranks immediately below themselves in their groups hierarchy. In contrast, lower-cost aggressive interactions are expressed towards group members further down the hierarchy. By directly evaluating differences in the strategic use of higher- and lower-cost aggressive interactions towards competitors, we show that individuals disproportionately use highest-cost interactions--such as chases--towards males found one to three ranks below themselves. Our results support the hypothesis that the costs associated with different interaction types can determine their expression in social groups with steep dominance hierarchies.

animal behavior and cognition↗

bioRxiv2020

Social network architecture and the tempo of cumulative cultural evolution

The ability to build upon previous knowledge--cumulative cultural evolution--is a hallmark of human societies. While cumulative cultural evolution depends on the interaction between social systems, cognition and the environment, there is increasing evidence that cumulative cultural evolution is facilitated by larger and more structured societies. However, such effects may be interlinked with patterns of social wiring, thus the relative importance of social network architecture as an additional factor shaping cumulative cultural evolution remains unclear. By simulating innovation and diffusion of cultural traits in populations with stereotyped social structures, we disentangle the relative contributions of network architecture from those of population size and connectivity. We demonstrate that while more structured networks, such as those found in multilevel societies, can promote the recombination of cultural traits into high-value products, they also hinder spread and make products more likely to go extinct. We find that transmission mechanisms are therefore critical in determining the outcomes of cumulative cultural evolution. Our results highlight the complex interaction between population size, structure and transmission mechanisms, with important implications for future research.

evolutionary biology↗