High early lactational synchrony within baboon groups predicts increased female-female competition and infant...

Area of Science:

• Behavioral Ecology
• Primatology
• Evolutionary Biology

Background:

• Social group composition influences individual fitness through interactions.
• Synchronized reproduction, particularly among females with infants, can intensify competition.
• This competition may negatively impact infant survival.

Purpose of the Study:

• To investigate the impact of early lactational synchrony on female-baboon agonistic interactions.
• To examine the relationship between early lactational synchrony and infant survival in wild baboons.
• To understand how social dynamics shape reproductive phenology in a nonseasonal breeder.

Main Methods:

• Analysis of decades of data on wild baboons (Papio sp.) in Amboseli, Kenya.
• Quantification of 'early lactational synchrony' as the proportion of females with infants <90 days old.
• Statistical examination of the correlation between synchrony, agonistic interactions, and infant mortality.

Main Results:

• Increased early lactational synchrony correlated with a higher frequency of female-female agonistic interactions.
• Females in postpartum amenorrhea received more agonistic interactions during high synchrony periods.
• High early lactational synchrony was a strong predictor of increased infant mortality.

Conclusions:

• Social dynamics, including competition among reproductive females and harassment from nonreproductive females, significantly affect reproductive outcomes.
• These findings suggest that social competition may select against synchronous reproduction in baboons.
• Early lactational synchrony has profound fitness consequences for both mothers and infants.