Final Activity Report Summary - HONEYBEE POLYANDRY (Polyandry and mate choice in the honeybee)
The evolution of multiple-mating by females (polyandry) represents a fundamental problem in behavioural ecology. While costs are generally assumed to be large, clear benefits have remained elusive. Our limited understanding is in spite of polyandry having substantial implications for the conflict of interests between the sexes, sexual selection and speciation. The problem is acute in the social insects because their particular biology means that many hypothesised benefits are unlikely to apply to them and the behaviour is most probably associated with greater direct and evolutionary costs than in non-social animals.
Yet, accurate data on the costs of polyandry in social insects are almost completely lacking, little is known about the mechanisms underlying the decision to engage in polyandry or whether females can express mate choice, and one of the best supported hypotheses for polyandry in non-social animals, that it reduces the fitness costs of genetically incompatible matings, has never been investigated in social insects.
The project used the honeybee as the model organism to address these key knowledge gaps. Honeybees are one of the few social insects in which the costs of polyandry can be accurately quantified. Using a novel set-up to control mating flights, almost 2 000 flights were observed during over 5 000 hours of observation. The costs of mating were quantified and were found to be very low. This was the case in two distinctly different geographical locations indicating that the result is robust and widely applicable. The mating frequency of queens was also related to environmental conditions at the time of flight and the role of the enigmatic mating plug deposited by honeybee males when they mate was established.
In addition, the question of whether or not females are able to express either pre- or post-copulatory mate choice was examined along with the fitness implications of a lack of choice. In addition to providing insight into the evolution of polyandry, the results also suggest ways in which the success of queen production may be improved, thus informing best practice in the beekeeping industry.
Yet, accurate data on the costs of polyandry in social insects are almost completely lacking, little is known about the mechanisms underlying the decision to engage in polyandry or whether females can express mate choice, and one of the best supported hypotheses for polyandry in non-social animals, that it reduces the fitness costs of genetically incompatible matings, has never been investigated in social insects.
The project used the honeybee as the model organism to address these key knowledge gaps. Honeybees are one of the few social insects in which the costs of polyandry can be accurately quantified. Using a novel set-up to control mating flights, almost 2 000 flights were observed during over 5 000 hours of observation. The costs of mating were quantified and were found to be very low. This was the case in two distinctly different geographical locations indicating that the result is robust and widely applicable. The mating frequency of queens was also related to environmental conditions at the time of flight and the role of the enigmatic mating plug deposited by honeybee males when they mate was established.
In addition, the question of whether or not females are able to express either pre- or post-copulatory mate choice was examined along with the fitness implications of a lack of choice. In addition to providing insight into the evolution of polyandry, the results also suggest ways in which the success of queen production may be improved, thus informing best practice in the beekeeping industry.