Behavioral plasticity in nest residency compensates for inbreeding depression in male prairie voles

Inbreeding negatively affects offspring production and survival in many species, but the fitness characteristics of adult inbred individuals are rarely evaluated. We examined the impact of inbreeding on the fitness of adult prairie voles (Microtus ochrogaster) under ecologically relevant conditions by releasing equal numbers of inbred and noninbred adults into 0.1 ha small mammal enclosures. The founding adult male and female prairie voles showed strong inbreeding depression that persisted into the third generation, despite the absence of additional inbreeding events. However, we found evidence that inbred males could ameliorate the negative inbreeding effects through a behavioral strategy: living at the nest with the mother of their offspring. Although they themselves produced fewer offspring, inbred males pursuing this reproductive strategy had offspring with increased reproductive success, resulting in equal numbers of grand-offspring produced by inbred and noninbred males. Our data demonstrate that a single generation of inbreeding can have lasting effects, but behavioral compensation for inbreeding effects is also possible.