Final answer:
Simmons et al found that sperm-depleted male fruit flies preferred to mate with larger, more fecund females after mating. This behavior increased their chances of producing offspring and supported Baker's assumptions about human sperm competition morphs.
Step-by-step explanation:
Simmons et al conducted a study on fruit flies (Drosophila melanogaster) to investigate the assumptions made by Baker regarding human sperm competition morphs. They found that after mating, sperm-depleted male fruit flies preferred to mate with larger, more fecund females rather than smaller females. This change in behavior was advantageous for the sperm-depleted males as it increased their chances of producing offspring. The study suggests that genes influencing the behavior of sperm-depleted males to choose larger females were selected, supporting Baker's assumptions about human sperm competition morphs.