Consequences of Fatherhood in the Biparental California Mouse (Peromyscus californicus): Locomotor Performance, Metabolic Rate, and Organ Masses

AbstractAlthough effects of motherhood on mothers have been well documented in mammals, the effects of fatherhood on fathers are not well known. We evaluated effects of being a father on key metabolic and performance measures in the California mouse, Peromyscus californicus. California mice are genetically monogamous in the wild, and fathers show similar parental behavior to mothers, with the exception of lactation. To investigate the impact of fatherhood on fathers, focal males were paired with an intact female (breeding males), a tubally ligated female (nonbreeding males), or another male (virgins). Starting 3–5 d after the birth of each breeding pair’s first litter, males were tested for locomotor performance (maximum sprint speed, treadmill endurance), basal metabolic rate (BMR), and maximum oxygen consumption (V˙O2max⁡). At the end of the 11-d test period, mice were euthanized, hematocrit was determined, and organs were weighed. Speed, endurance, and V˙O2max⁡ were significantly repeatable between two...