Abstracts (first author)
Haplodiploidy and the evolution of eusociality: worker revolution
Hamilton suggested that haplodiploidy predisposes species to the evolution of eusociality. This is because haplodiploidy increases the genetic similarity of sisters above that of mother and daughter, which could potentially favour an individual to give up her own future reproductive success in order to devote her life to sib-rearing. Trivers and Hare noted that, in order for this to work, helpers need to direct their altruism preferentially towards sisters rather than brothers. Building upon this idea, they proposed two biological scenarios whereby haplodiploidy could promote eusociality: (a) workers biasing the sex allocation of the queen’s brood towards females; and (b) workers replacing the queen’s sons with their own sons. However, biased sex allocation and worker reproduction can have multiple consequences for both the genetic structure of colonies and the reproductive values of males and females. Here we determine the net effect of all these consequences, for the two scenarios whereby the workers seize control of reproduction. We find that: (1) worker control of sex allocation may promote helping, but this effect is likely to be weak and short-lived; and (2) worker reproduction tends to inhibit rather than promote helping.