Autor(es)

Ferreira, Helena Mendes ; Alves, Denise Araujo ; Cool, Lloyd ; Oi, Cintia Akemi ; Oliveira, Ricardo Caliari ; Wenseleers, Tom

• Tipo de documento: Artigo Científico
• Fonte: EVOLUTION LETTERS; v. 8, n. 3, p. 10-pg., 2024-01-11.

Resumo

In the field of social evolution, inclusive fitness theory has been successful in making a wide range of qualitative predictions on expected patterns of cooperation and conflict. Nevertheless, outside of sex ratio theory, inclusive fitness models that make accurate quantitative predictions remain relatively rare. Past models dealing with caste fate conflict in insect societies, for example, successfully predicted that if female larvae can control their own caste fate, an excess should opt to selfishly develop as queens. Available models, however, were unable to accurately predict levels of queen production observed in Melipona bees-a genus of stingless bees where caste is self-determined-as empirically observed levels of queen production are approximately two times lower than the theoretically predicted ones. Here, we show that this discrepancy can be resolved by explicitly deriving the colony-level cost of queen overproduction from a dynamic model of colony growth, requiring the incorporation of parameters of colony growth and demography, such as the per-capita rate at which new brood cells are built and provisioned, the percentage of the queen's eggs that are female, costs linked with worker reproduction and worker mortality. Our revised model predicts queen overproduction to more severely impact colony productivity, resulting in an evolutionarily stable strategy that is approximately half that of the original model, and is shown to accurately predict actual levels of queen overproduction observed in different Melipona species. Altogether, this shows how inclusive fitness models can provide accurate quantitative predictions, provided that costs and benefits are modeled in sufficient detail and are measured precisely. In a fascinating new study, scientists from the Laboratory of Socio-ecology and Social Evolution at the University of Leuven delve into conflicts linked with the choice to become either a queen or a worker in bee societies. Focusing on stingless bees and honeybees, they explore how the ability to control one's own caste fate can result in many choosing to become queens. In particular, the authors show that in Melipona stingless bees, where caste is self-determined, about 10% of all females selfishly opt to become queens, while in related species where caste is nutritionally determined, queens are found to be produced at a rate that aligns with colony needs. The researchers further develop a theoretical model that accurately predicts levels of queen production in these Melipona bees, showing that an evolutionary equilibrium is reached when the individual benefit of becoming a queen balances with the collective cost that would occur if too many became queens and too few workers would be produced. This work provides a compelling example of the power of evolutionary theory in making accurate predictions in the field of social evolution, and offers new insights into how conflicts between individual and collective interests play out in animal societies. Bee societies have a strict reproductive division of labor between reproductively active queens and mostly sterile workers. In honeybees and also in most tropical stingless bees, who gets to become a queen is decided by nutrition: only larvae that receive enough high-quality food can make it into a queen. In one particular group of Melipona stingless bees, however, developing larvae themselves have been found to have the power to determine their own caste fate. Under such circumstances, the question becomes what processes prevent most from selfishly opting to become queens. The present article uses an inclusive fitness model to show that the proportion that develops as a queen (ca. 10%) is such that the individual reproductive benefit of developing as a queen exactly balances with the collective, indirect fitness costs caused by decreased swarm and male production. This is the first time that such an accurate match between theoretically predicted and empirically observed levels of queen production is obtained, which was possible thanks to the use of a dynamic model that determined how overproducing queens would reduce the success of the colony as a whole. Model predictions were further validated by comparison with other bee species where caste is nutritionally determined, and where queens were shown to be produced in line with colony needs, at a rate that was two orders of magnitude lower than in Melipona. Overall, this analysis demonstrates the power of inclusive fitness theory in being able to make accurate quantitative predictions in the field of social evolution and shows how conflicts between individual and collective interests play out in animal societies. (AU)

• Processo FAPESP: 05/58093-8 - Estratégias reprodutivas em Melipona, com ênfase em pequenas populações de Melipona scutellaris (Apidae, Meliponini)
• Beneficiário: Denise de Araujo Alves
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto