Meeting Abstract
The prairie vole (Microtus ochrogaster) is a socially monogamous rodent, in which individuals form long-term pairbonds that are characterized by exclusive home ranges. Males monopolize one female, guarding her to secure intra-pair fertilizations (IPFs) and ensure paternity. However, males are opportunistic and seek additional matings with females, leaving their partner unguarded. Based on semi-natural field studies, some have suggested that the success associated with a male’s decision to seek more mates over guarding his partner is impacted by the amount of other males leaving their nests to seek extra-pair fertilizations (EPFs). The amount of EPF-seeking males impacts both the likelihood of encountering an unguarded paired female and of being cuckolded (losing IPFs). It remains unclear under which conditions it is optimal to stay and guard or seek EPFs. Using field data to generate parameters, we used optimal performance modeling to ask when is it most reproductively advantageous for a male to seek EPFs despite the risk of losing IPFs. We found that at high levels of EPF-seeking in the population, the rate of EPFs for a subject begins to slowly outpace the rate of cuckolding. This result suggests that mate searching becomes the optimal tactic for the subject once the population of EPF-seeking males reaches approximately 60%. We also found that the ratio of EPFs to IPFs for the subject dramatically changes as EPF-seeking percentages in the population increase, though total fertilizations remain constant. Our results show the dynamic nature of reproductive decision-making in the prairie vole model, and demonstrate that alternative reproductive decisions yield subtle differences despite appearing as balanced strategies.
