Question

Spotted hyenas are an unusual species. They are extremely socialand have very complex social behavior. The females are extremelyaggressive and are dominant to the far less aggressive males.Female genitalia is extremely masculinized with no external vaginaand a hypertrophied clitoris that resembles a penis in size, shape,and the ability to become erect. They mate and give birth throughthis organ, which causes as many as 18% to die during their firstbirthing and 60% of the survivors to lose their firstbornyoung.

This is a female.
Note the pseudo-penis.

This is a female.
Note the pseudo-penis.

Several hypotheses have been floated as to why such a thingwould evolve. For each of these hypotheses, lay out thefollowing:

• What sort of evolutionary process produced the masculinizedgenitalia?
• What evidence would you need to support/refute thathypothesis?

Hypotheses:

• Mimicry: Females are using these masculine genitalia to mimicthe submission rituals of the males.

• Anti-Infanticide: Females are aggressive as a countermeasure tomale infanticide (males killing infants). The aggressiveness iscaused by increased androgens (male sex hormones like testosterone)in the females, which in turn causes masculinized genitalia.

• Competition: Dominant females produce more cubs and her cubshave a strong advantage in access to meat. The aggressiveness iscaused by increased androgens (male sex hormones like testosterone)in the females, which in turn causes masculinized genitalia.