Variation in male courtship effort due to female identity. The two vertically attached symbols represent courtship efforts by the two males that courted the same stimulus female. The larger of these two males is indicated with a larger symbol and the smaller male with a smaller symbol. The two females within each experimental unit (i.e. the two females that were courted by the same two males) are identified by a shared combination of symbol colour and type.
Lehtonen et al. BMC Evolutionary Biology 2011 11:233 doi:10.1186/1471-2148-11-233