Abstract
The authors examined the effects of the father on the development of offspring in Mongolian gerbil (Meriones unguiculatus). In the “father-absent” group (11 litters : n=42), the male parent was removed on the day, the pups were born. They were then reared only by the mother until weaning at 30 days of age. In the “father-present” group (11 litters : n=55), the pups were reared by both parents. More of the pups in the “father-present” group survived the nursing period than in the “father-absent” group. The body weight of the male pups in the “father-present” group (n=20) was heavier than in the “father-absent” group (n=27) after 13 days from birth, and the difference between the groups remained after weaning. In an open-field test of male subjects at 60 days, the subjects of the “father-present” group (n=20) tended to reduce their activity level later in the test period, more than the “father-absent” group (n=27) did. Additionally, in aggression tests at 90 days, the males (n=17) reared by both parents often displayed submissive posture when they were pinned down by an intruder male, while none of the absence group (n=18) did. These results were discussed in relation to the adaptive functions of male parents in this species.
