by Sander van Doorn.
This summer (29 August - 2 September 2000) Franjo Weissing organised a symposium and a PhD summer school on the Evolutionary Ecology of Sex. Both events took place at the Biological Centre in Haren (University of Groningen). The symposium was originally planned as a small-scale event, but the subject aroused a lot of scientific interest, reflected by the fact that it attracted an impressive number of 180 people. Among these were many of the leading figures of the field, as well as 70 PhD students who also attended the summer school. The scientific program aimed at bringing together empirical and theoretical biologists, and at reviewing the field from both points of view. It was this mix, together with the mix of young and veteran scientists, that catalysed fruitful interactions and made the symposium both scientifically and socially a great success. The three days of the symposium were filled with lecture sessions on particular topics in the field (evolution of sex, sex determination, sex allocation, sexual selection, sexual conflict and battle of the sexes), a poster session and several discussion sessions. Here I will discuss each of the lecture sessions briefly, focusing mainly on the theoretical contributions.