In many katydids, the male delivers his sperm to the female in a large spermatophore that...

In many katydids, the male delivers his sperm to the female in a large spermatophore that contains nutrients the female eats (for a photo, see Gwynne 1981).The female uses these nutrients in the production of eggs. Darryl Gwynne and L. W. Simmons (1990) studied the behavior of caged populations of an Australian katydid under low-food (control) and high-food (extra) conditions. Some of their results are graphed in Figure. (The graph shows the results from four sets of replicate cages; calling males = number of males calling at any given time; matings>female = number of times each female mated; % reject by M = fraction of the time a female approached a male for mating and was rejected; % reject by F = fraction of the time a female approached a male but then rejected him before copulating; % with F–F comp = fraction of matings in which one or more females were seen fighting over the male.) Based on the graphs, when were the females choosy and the males competitive? When were the males choosy and the females competitive? Why?

Figure Behavior of male and female katydids under control versus extra-food conditions Data from Gwynne and Simmons (1990).