Biology subjects

Pavez-Fox, M. A.

Publications and source records attributed to Pavez-Fox, M. A..

5 recordsLinked to original sources

bioRxiv2024

Social ageing can protect against infectious disease in a group-living primate

The benefits of social living are well established, but sociality also comes with costs, including infectious disease risk. This cost-benefit ratio of sociality is expected to change across individuals lifespans, which may drive changes in social behaviour with age. To explore this idea, we combine data from a group-living primate for which social ageing has been described with epidemiological models to show that having lower social connectedness when older can protect against the costs of a hypothetical, directly transmitted endemic pathogen. Assuming no age differences in epidemiological characteristics (susceptibility to, severity, and duration of infection), older individuals suffered lower infection costs, which was explained largely because they were less connected in their social networks than younger individuals. This benefit of social ageing depended on epidemiological characteristics and was greatest when infection severity increased with age. When infection duration increased with age, social ageing was beneficial only when pathogen transmissibility was low. Older individuals benefited most from having a lower frequency of interactions (strength) and network embeddedness (closeness) and benefited less from having fewer social partners (degree). Our study provides a first examination of the epidemiology of social ageing, demonstrating the potential for pathogens to influence evolutionary dynamics of social ageing in natural populations.

animal behavior and cognition↗

bioRxiv2024

The impact of kinship composition on social structure

The relatedness between group members is a potential driver of variation in social structure. Relatedness predicts biases in partner choice and formation of strong relationships among group members. As such, groups that differ in their percentage of non-kin dyads, i.e., in their kinship composition, should therefore differ in the structure of their social networks. Yet the relationship between kinship composition and social structure remains unclear. Here, we used long-term social and pedigree data from a population of rhesus macaques to investigate the relationship between kinship composition and the connectivity, cohesion, potential for transmission and social differentiation of the social networks of adult female macaques. We found no evidence that the social structure of groups composed of greater proportion of unrelated females differ from that of groups with a lower proportion of non-kin. To investigate this unexpected finding, we built agent-based models parameterised with the empirical data to further explore (1) the expected relationship between kinship composition and social structure and (2) why we did not find such a relationship in the empirical data. Agent-based models showed that kinship composition can influence social structure in populations similar to the one studied, but that this effect may only be detectable with a sample size even larger than ours (19 group-years) and with greater variance in kinship composition (proportion of non-kin varied between 0.830-0.922 in the empirical data). The relationship between kinship composition and social structure might be more apparent when comparing data from species that differ strongly in their social organisation, translating into marked differences in kinship composition. This further emphasises the importance of reporting existing and future kinship composition data to deepen our understanding of the evolution of sociality and highlights the potential of agent-based models to better understand empirical results.

animal behavior and cognition↗

bioRxiv2023

The biology of aging in a social world: insights from free-ranging rhesus macaques

Social adversity can increase the age-associated risk of disease and death, yet the biological mechanisms that link social adversities to aging remain poorly understood. Long-term naturalistic studies of nonhuman animals are crucial for integrating observations of social behavior throughout an individuals life with detailed anatomical, physiological, and molecular measurements. Here, we synthesize the body of research from one such naturalistic study system, Cayo Santiago Island, which is home to the worlds longest continuously monitored free-ranging population of rhesus macaques. We review recent studies of age-related variation in morphology, gene regulation, microbiome composition, and immune function. We also discuss ecological and social modifiers of age-markers in this population. In particular, we summarize how a major natural disaster, Hurricane Maria, affected rhesus macaque physiology and social structure and highlight the context-dependent and domain-specific nature of aging modifiers. Finally, we conclude by providing directions for future study, on Cayo Santiago and elsewhere, that will further our understanding of aging across different domains and how social adversity modifies aging processes.

immunology↗

bioRxiv2022

Reduced injury risk links sociality to survival in a group-living primate

Affiliative social relationships and high social status predict longer lifespans in many mammal species, including humans. Yet, the mechanisms by which these components of sociality influence survival are still largely unknown. Using 10 years of data and over 1000 recorded injuries from a free-ranging population of rhesus macaques (Macaca mulatta), we investigated two possible mechanisms that could underpin the relationship between sociality and survival: sociality (1) reduces injury risk; and/or (2) increases the probability of survival after an injury. We found that sociality can affect an individuals survival by influencing their risk of injury, but had no effect on the probability of injured individuals dying. Individuals with more affiliative partners experienced fewer injuries compared to less socially integrated. Social status was also associated with lower risk of injury, particularly for older high-ranking individuals. These results represent the first demonstration of a link between social integration and fatal injury risk in a group-living species, and are the first to link social status, injury risk and survival outside of humans. Collectively, our results offer insights into a mechanism that can mediate the well-known benefits of sociality on an individuals fitness.

evolutionary biology↗

bioRxiv2021

Sociodemographic effects on immune cell composition in a free-ranging non-human primate.

Increasing age is associated with dysregulated immune function and increased inflammation- patterns that are also observed in individuals exposed to chronic social adversity. Yet we still know little about how social adversity impacts the immune system and how it might promote age-related diseases. Here, we investigated how immune cell diversity varied with age, sex and social adversity (operationalized as low social status) in free-ranging rhesus macaques. We found age-related signatures of immunosenescence, including lower proportions of CD20+ B cells, CD20+/CD3+ ratio, and CD4+/CD8+ T cell ratio - all signs of diminished antibody production. Age was associated with higher proportions of CD3+/CD8+ Cytotoxic T cells, CD16+/CD3-Natural Killer cells, CD3+/CD4+/CD25+ and CD3+/CD8+/CD25+ T regulatory cells, and CD14+/CD16+/HLA-DR+ intermediate monocytes, and lower levels of CD14+/CD16-/HLA-DR+ classical monocytes, indicating greater amounts of inflammation and immune dysregulation. We also found an effect of exposure to social adversity (i.e., low social status) that was sex-dependent. High-status males, relative to females, had higher CD20+/CD3+ ratios and CD16+/CD3 Natural Killer cell proportions, and lower proportions of CD8+ Cytotoxic T cells. Further, low status females had higher proportions of cytotoxic T cells than high status females, while the opposite was observed in males. High status males had higher CD20+/CD3+ ratios than low status males. Together, our study identifies immune cell types that differ by age in a human-relevant primate model animal, and demonstrates a novel link between sex-dependent immunity and social adversity.

immunology↗