Abstracts (first author)
Sex ratios favour an evolutionary transition in social behaviour and life-historyPDF
The evolution of eusociality, where some individuals refrain from reproduction to help others to reproduce, remains one of the biggest challenges for evolutionary theory. From a Darwinian perspective individuals are expected to maximize their own reproduction rather than help others reproduce. Different theoretical frameworks have been developed to explain why individuals would be selected to have reproductive altruism. In particular, kin selection theory has made salient the relevance of sex determination systems and sex ratios in the evolution of altruism. However, beyond changes in social behaviour, the transition between solitary and eusocial life involves also changes in life-history traits that have not been explain theoretically. Here we show that the coevolution of sex ratios and helping behaviour causes not only the evolution of eusociality, but also a transition between bivoltine and a univoltine life history. Our model shows that the haplodiploidy genetic systems can favour the evolution of eusociality, however this depends on the type of life history under which selection takes place. This is the first theoretical explanation for a life history transition during the evolution of eusociality. It points out to the importance of life-history conditions on the evolution of sex ratios and social behaviour.