Behaviour 2019
Determinants of male reproductive success in a social rodent with strong post-copulatory selection
Riley C. Jellicoe, Jane M. Waterman. University of Manitoba , Winnipeg, Manitoba, Canada

Male Cape ground squirrels (Xerus inauris) are long-lived compared to many rodents, suggesting they have a slow life-history, and that males invest in long-term survival over short-term reproduction. Males have two alternative reproductive tactics. At maturity, they either remain with their family group (natal) or disperse into all-male groups (band). We hypothesized that age and body condition will positively influence reproductive success and that reproductive success between tactics will differ. We used trapping and genetic data to determine reproductive success, body condition and tactic for each male (n = 369). We found that older males and those in better body condition were more likely to sire offspring, supporting our major hypothesis. Body condition and age were positively correlated as older males were more likely to be in good condition compared to younger males and this difference was more dramatic in natal males vs band males. Natal males were also younger than band males when they first successfully reproduced. Our results suggest that tactic, age and body condition are important determinants of fitness in males, which may lead to selection for a slower life-history.