Evolution of sex differences in cooperation can be explained by trade-offs with dispersal.

Explaining the evolution of sex differences in cooperation remains a major challenge. Comparative studies highlight that offspring of the more philopatric sex tend to be more cooperative within their family groups than those of the more dispersive sex but we do not understand why. The leading "Philopatry hypothesis" proposes that the more philopatric sex cooperates more because their higher likelihood of natal breeding increases the direct fitness benefits of natal cooperation.

When wax wanes: competitors for beeswax stabilize rather than jeopardize the honeyguide-human mutualism.

Many mutualisms are exploited by third-party species, which benefit without providing anything in return. Exploitation can either destabilize or promote mutualisms, via mechanisms that are highly dependent on the ecological context. Here we study a remarkable bird-human mutualism, in which wax-eating greater honeyguides () guide humans () to wild bees' nests, in an exchange of knowledge about the location of nests for access to the wax combs inside.

Safeguarding human-wildlife cooperation.

Human-wildlife cooperation occurs when humans and free-living wild animals actively coordinate their behavior to achieve a mutually beneficial outcome. These interactions provide important benefits to both the human and wildlife communities involved, have wider impacts on the local ecosystem, and represent a unique intersection of human and animal cultures. The remaining active forms are human-honeyguide and human-dolphin cooperation, but these are at risk of joining several inactive forms (including human-wolf and human-orca cooperation).

Exploitative leaders incite intergroup warfare in a social mammal.

Collective conflicts among humans are widespread, although often highly destructive. A classic explanation for the prevalence of such warfare in some human societies is leadership by self-serving individuals that reap the benefits of conflict while other members of society pay the costs. Here, we show that leadership of this kind can also explain the evolution of collective violence in certain animal societies.

The development of individual differences in cooperative behaviour: maternal glucocorticoid hormones alter helping behaviour of offspring in wild meerkats.

The phenotype of parents can have long-lasting effects on the development of offspring as well as on their behaviour, physiology and morphology as adults. In some cases, these changes may increase offspring fitness but, in others, they can elevate parental fitness at a cost to the fitness of their offspring. We show that in Kalahari meerkats ( Suricata suricatta), the circulating glucocorticoid (GC) hormones of pregnant females affect the growth and cooperative behaviour of their offspring.

Rank-Related Contrasts in Longevity Arise from Extra-Group Excursions Not Delayed Senescence in a Cooperative Mammal.

In many cooperatively breeding animal societies, breeders outlive non-breeding subordinates, despite investing heavily in reproduction [1-3]. In eusocial insects, the extended lifespans of breeders arise from specialized slowed aging profiles [1], prompting suggestions that reproduction and dominance similarly defer aging in cooperatively breeding vertebrates, too [4-6]. Although lacking the permanent castes of eusocial insects, breeders of vertebrate societies could delay aging via phenotypic plasticity (similar rank-related changes occur in growth, neuroendocrinology, and behavior [7-10]), and such plastic deferment of aging may reveal novel targets for preventing aging-related diseases [11].

Effects of early-life competition and maternal nutrition on telomere lengths in wild meerkats.

Early-life adversity can affect health, survival and fitness later in life, and recent evidence suggests that telomere attrition may link early conditions with their delayed consequences. Here, we investigate the link between early-life competition and telomere length in wild meerkats. Our results show that, when multiple females breed concurrently, increases in the number of pups in the group are associated with shorter telomeres in pups.

Oxidative stress and life histories: unresolved issues and current needs.

Life-history theory concerns the trade-offs that mold the patterns of investment by animals between reproduction, growth, and survival. It is widely recognized that physiology plays a role in the mediation of life-history trade-offs, but the details remain obscure. As life-history theory concerns aspects of investment in the soma that influence survival, understanding the physiological basis of life histories is related, but not identical, to understanding the process of aging.

The oxidative costs of reproduction are group-size dependent in a wild cooperative breeder.

Life-history theory assumes that reproduction entails a cost, and research on cooperatively breeding societies suggests that the cooperative sharing of workloads can reduce this cost. However, the physiological mechanisms that underpin both the costs of reproduction and the benefits of cooperation remain poorly understood. It has been hypothesized that reproductive costs may arise in part from oxidative stress, as reproductive investment may elevate exposure to reactive oxygen species, compromising survival and future reproduction and accelerating senescence.

Immune response in a wild bird is predicted by oxidative status, but does not cause oxidative stress.

The immune system provides vital protection against pathogens, but extensive evidence suggests that mounting immune responses can entail survival and fecundity costs. The physiological mechanisms that underpin these costs remain poorly understood, despite their potentially important role in shaping life-histories. Recent studies involving laboratory models highlight the possibility that oxidative stress could mediate these costs, as immune-activation can increase the production of reactive oxygen species leading to oxidative stress.