Thomas M Houslay

1 Introduction Aging is associated with increased vulnerability to infection, elevated prevalence of chronic disease, impaired wound healing, and reduced vaccination efficiency (López-Otín et al. 2013; Baechle et al. 2023). These age-related complications are driven by immune dysfunction, which is characterized by chronic inflammation and inadequate immune responses (Baechle et al. 2023).

Abstract The vertebrate stress response comprises a suite of behavioural and physiological traits that must be functionally integrated to ensure organisms cope adaptively with acute stressors. Natural selection should favour functional integration, leading to a prediction of genetic integration of these traits.

Many animals that live in social groups of stable composition compete intensely with their neighbours for territory, resources and mates. While much of the competition between groups is indirect (e.g. via scent marking behaviour or vocal exchanges), some species directly engage in physical aggression between groups.