Male-Mediated Maturation in Wild Geladas

Area of Science:

• Primate reproductive ecology
• Behavioral endocrinology
• Mammalian reproductive strategies

Background:

• Female maturation timing in wild mammals is influenced by ecological and social factors.
• Novel male presence can accelerate maturation, while related males can inhibit it.
• Male-mediated maturation has not been systematically documented in wild primate populations.

Purpose of the Study:

• To provide the first evidence of male-mediated maturation in a wild primate, the gelada.
• To investigate the effects of male takeovers on female maturation timing.
• To explore the potential neuroendocrine mechanisms underlying these changes.

Main Methods:

• Observational study of a wild gelada population.
• Analysis of female maturation timing relative to male takeovers.
• Measurement of fecal estrogens to assess hormonal changes.

Main Results:

• Young females were three times more likely to mature following a male takeover.
• Maturation timing varied, including accelerated (Vandenbergh effect) and delayed (inbreeding avoidance) patterns.
• Male takeovers induced estrogen surges in immature females, regardless of maturation status.

Conclusions:

• Specific males are associated with the onset of maturation in wild geladas.
• Male takeovers can trigger both accelerated and delayed maturation through hormonal changes.
• Neuroendocrine processes likely govern diverse male-mediated maturation effects.