As a young PhD student, just about to write my first paper, I gave a talk at a meeting in London about my first finished research project. Because I had to rush back to the airport to catch my flight, I could not join the meeting’s participants for a drink and a chat in the local pub. The next day though, I received an email from one of the organisers of the meeting, telling me that a colleague was just about to submit a manuscript on the topic I had talked about. ‘Contact the author’, he suggested. And I did. I instantly received the manuscript, and after having read the abstract, my heart sank. This could have been my paper! It explained why bumblebees produce what appears to be an excess of males, a question I thought I had found the answer to.
Bumblebees are social insects; colonies contain a single queen, mated to one male, and up to a few hundred workers who are all female. Colonies are around for a single season and towards the end of summer instead of new workers, males and new queens are produced. The males will mate with queens from other colonies, and those mated queens are the only individuals that overwinter, starting new colonies in spring. According to theory, bumblebee colonies should put more energy into raising new queens than males. This is because of the peculiar way sex is determined in the Hymenoptera, the class of insects that bumblebees are part of. Males only carry half of the genetic material females carry, leading to asymmetrical relatedness within colonies. Thus, all else being equal, the average worker in a colony would benefit from investing more in sisters that are raised as new queens, than in brothers.
The theory on which the predictions are based seemed to hold in many other instances, so what was different about bumblebees? I had collected data on the ratio of males to queens that colonies produced and when these colonies started to produce sexual individuals instead of workers. Analysing my data I realised there were two types of colonies: those that quickly started to produce sexual individuals, and others that took much longer. The former invested much more in male production, whereas the latter mainly produced new queens. Hence, it appeared colonies adopted different strategies, and I hypothesised that both strategies could be equally successful, provided a population contains both. This was exactly the point of Andrew Bourke’s paper.
After my initial shock and disappointment, as now I would not be the first to explain the overproduction of males, I realised that the firm theoretical framework provided in Bourke’s paper could strengthen my own work. The experience also had a personal influence on me, as I realised that established scientists were happy to share their unpublished work with mere PhD students and even provide comments, as Andrew did. I am a better scientist and mentor thanks to such positive interactions early on in my career.