Final answer:
The option that has not been proposed to explain sexual selection by mate choice is e. Scramble competition. Sexual selection hypotheses include direct benefits, antagonistic coevolution, indirect benefits, and sensory bias. Scramble competition describes intrasexual competition, not mate choice.
Step-by-step explanation:
The student's question asks which of the provided options has not been proposed to explain sexual selection by mate choice. The correct answer is e. Scramble competition. Sexual selection is a special case of natural selection that affects an individual's ability to mate and thus produce offspring. It can occur as either intrasexual selection, involving competition among the same gender (such as male-male competition), or intersexual selection, involving one gender choosing mates from the other (such as female choice based on male traits).
The hypotheses explaining mate choice in sexual selection include:
- a. Direct benefits: choosing mates which provide resources or other immediate advantages to the choosing sex.
- b. Antagonistic coevolution: where the sexes have conflicting optimal fitness strategies.
- c. Indirect benefits: choosing mates with traits that will lead to greater reproductive success for the offspring.
- d. Sensory bias: a preference for certain traits that correspond to preexisting sensory biases.
However, e. Scramble competition is not a hypothesis related to mate choice but rather refers to a type of intrasexual competition where individuals compete with each other over access to mates, often in a free-for-all manner.