Combining Behavior and Genetics to Investigate Resident Male Reproduction in Blue Monkeys

In one-male groups, one resident male monopolizes access to group-living females at all times. Increased access to females is presumed to give single resident males a reproductive advantage, however, genetic evidence from blue monkeys indicates that the resident male often loses a large portion of group reproduction to outside males. In this study, we evaluated the impact of female reproductive synchony, intruder pressure, and length of resident tenure on resident male paternity success. Our results indicated that the number of simultaneously conceptive females and tenure length were negatively correlated with the probability that the resident male sired an infant. When many conceptive females were present, the resident male was unable to guard all at the same time and was more likely to lose paternity to extra-group males. Additionally, if females choose mates to increase the genetic diversity of their offspring, they may avoid reproducing with long-tenured males and residents would experience a reduction in paternity success over their tenure.