Biology subjects

Kreider, J. J.

Publications and source records attributed to Kreider, J. J..

6 recordsLinked to original sources

bioRxiv2026

Caste-specific ageing emerges from the evolution of resource allocation in eusocial insects

Eusocial insects have extreme intraspecific lifespan variation, where queens are long-lived (up to 30 years) whereas workers only live for a few months or years at most. Several studies have invoked the disposable soma theory to explain the evolution of caste-specific ageing in eusocial insects, which proposes that senescence results from a resource allocation trade-off between maintenance vs. reproduction. An extension of this theory to eusocial insects is that caste-specific ageing could emerge from a resource allocation trade-off between castes. However, to date this idea has not been formalised in a theoretical model. Here, we present an individual-based model for the evolution of ageing in social insects. In our model, queens and workers die when their nutritional state becomes too low. The evolving trait in our model is the age-specific resource allocation of individual workers, who can allocate resources between themselves, other workers, and the queen. We find that lifespan differences between queens and workers emerge from the evolved resource allocation within colonies, which are within the range of empirically observed lifespans of queens and workers in monogynous eusocial insects. Caste-specific ageing evolves in our model because queens obtain large amounts of resources, which allows them to be long-lived and highly fertile, whereas workers evolve to give resources away to enhance the queens reproduction and thereby their own indirect fitness. We also observe that age polyethism emerges, where young workers nurse the brood and older workers forage. Overall, our model demonstrates that both caste-specific ageing and age-related worker division of labour emerge as a consequence of evolved within-colony resource allocation.

evolutionary biology↗

bioRxiv2025

Low temperature triggers sociality in a facultatively social bee

The evolutionary transition to eusociality in the solitary ancestors of social insects, like ants, termites, wasps, and bees, may have been initiated by an environmental induction of group living. Plasticity in social behaviour in response to the environment can be found in facultatively social insects. However, it is currently unknown which environmental cues trigger the individual decision of an insect to nest solitarily or socially. Such environmental cues could be identified by exposing individuals of a facultatively social insect to experimentally manipulated cues in a controlled environment. Here, we report such an experiment with the facultatively social allodapine bee Exoneura robusta, which we exposed to different temperature and predation treatments in climate chambers. We observed that low temperature triggered the bees to behave more socially. Furthermore, there was substantial variation in the tendency to be social among individual bees. Our study identifies a specific environmental cue that triggers a plastic response in sociality. Such plasticity could be crucial at the origin of group living and social breeding, facilitating the evolution of eusociality in insects.

evolutionary biology↗

bioRxiv2024

Maternal manipulation of offspring size can trigger the evolution of eusociality in promiscuous species

Eusocial organisms typically live in colonies with one reproductive queen supported by thousands of sterile workers. It is widely believed that monogamous mating is a precondition for the evolution of eusociality. Here, we present a theoretical model that simulates a realistic scenario for the evolution of eusociality. In the model, mothers can evolve control over resource allocation to offspring, affecting offspring body size. The offspring can evolve body-size-dependent dispersal, by which they disperse to breed or stay at the nest as helpers. We demonstrate that eusociality evolves, even if mothers are not strictly monogamous, if mothers can constrain their offsprings reproduction by manipulation. We also observe the evolution of social polymorphism with small individuals that help and larger individuals that disperse to breed. Our model unifies the traditional kin selection and maternal manipulation explanations for the evolution of eusociality and demonstrates that - contrary to current consensus belief - eusociality can evolve despite highly promiscuous mating.

evolutionary biology↗

bioRxiv2023

Coevolution of larval signalling and worker response can trigger developmental caste determination in social insects

Eusocial insects belong to distinct queen and worker castes, which, in turn, can be divided into several morphologically specialised castes of workers. Caste determination typically occurs by differential nutrition of developing larvae. We present a model for the coevolution of larval signalling and worker task allocation - both modelled by flexible smooth reaction norms - to investigate the evolution of caste determination mechanisms and worker polymorphism. In our model, larvae evolve to signal their nutritional state to workers. The workers evolve to allocate time to foraging for resources versus feeding the brood, conditional on the larval signals and their body size. Worker polymorphism evolves under accelerating foraging returns of increasing body size, which causes selection to favour large foraging and small nursing workers. Worker castes emerge because larvae evolve to amplify their signals after obtaining some food, which causes them to receive more food, while the other larvae remain unfed. This leads to symmetry-breaking among the larvae who either are well-nourished or malnourished; thus, emerging as small or large workers. Our model demonstrates the evolution of nutrition-dependent caste determination and worker polymorphism by a self-reinforcement mechanism that evolves from the interplay of larval signalling and worker response to the signals.

evolutionary biology↗

bioRxiv2022

Resource sharing leads to the emergence of division of labour

Division of labour occurs in a broad range of organisms. Yet, how division of labour can emerge in the absence of pre-existing interindividual differences is poorly understood. Using a simple but realistic model, we show that in a group of initially identical individuals, division of labour emerges spontaneously if returning foragers share part of their resources with other group members. In the absence of resource sharing, individuals follow an activity schedule of alternating between foraging and other tasks. If non-foraging individuals are fed by other individuals, their alternating activity schedule becomes interrupted, leading to task specialisation and the emergence of division of labour. Furthermore, nutritional differences between individuals reinforce division of labour. Such differences can be caused by increased metabolic rates during foraging or by dominance interactions during resource sharing. Our model proposes a plausible mechanism for the self-organised emergence of division of labour in animal groups of initially identical individuals. This mechanism could also play a role for the emergence of division of labour during the major evolutionary transitions to eusociality and multicellularity.

evolutionary biology↗

bioRxiv2022

The evolution of ageing in cooperative breeders

Cooperatively breeding animals live longer than their solitary counterparts. The traditional explanation for this is that cooperative breeding evolves more readily in long-lived species. Here, we reverse this argument and show that long lifespans are an evolutionary consequence of cooperative breeding. Natural selection favours a delayed onset of senescence in cooperative breeders, relative to solitary breeders, because cooperative breeders have a delayed age of first reproduction due to reproductive queueing. Especially long lifespans evolve in cooperative breeders with age-dependent reproductive queueing. Finally, we show that lower genetic relatedness among group members leads to the evolution of longer lifespans. This is because selection against higher mortality is weaker when mortality reduces competition between relatives. Our results link the evolutionary theory of ageing with kin selection theory, demonstrating that the evolution of ageing in cooperative breeders is driven by the timing of reproduction and kin structure within breeding territories.

evolutionary biology↗