In many katydids, the male delivers his sperm to the female in a large spermatop

Question

In many katydids, the male delivers his sperm to the female in a large spermatophore that contains nutrients the female eats. The female uses these nutrients in the production of eggs. In one study of this behavior, researchers used caged populations of an Australian katydid (24 males and 24 females per cage) under low-food (control) and high-food (extra) conditions. The graphs below show the results from four sets of replicate cages. Dependent variables were: * calling males-number of males calling at any given time; * matings/female - number of times each female mated . % reject by N fraction of the time a female appora ched a male for mating and was rejected; . % reject by F fraction of the time a female apporached a male bu then rejected him before copulating; % with F-F comp the male fraction of matings in which one or more females were seen fighting over . Based on the graphs, when were the females choosy and the males competitive? When were the males choosy and the females competitive? Why? Explain your answer in terms of sexual selection theory. (6 pts) Calling males Matings/female % Reject by M 60 50 % Reject by F % with F-F comp 30 1 1.2 60 20 6 0.8 40 30 4 20 0.4 20 0 0 0 Control Extra Control Extra Control Extra Control Extra Control Extra Food level

Explanation / Answer

Depending on the graph, itseems that under control condition the percentage of calling males were less when compared to percentage of % with F-F comp, which was high. So, based on this we can say that under low food conditions the males were choosy and females were competitive because males used up their less energy towards females. whereas in case of % reject by F, females were choosy and males were competitive. Because of high food availability where females were less attracted as before copulating they have rejected males and also they tendency for multiple matings (matings / female).

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