A testosterone-mediated trade-off between parental and sexual effort in male mongolian gerbils (Meriones unguiculatus).

Effects of testosterone (T) on parental behavior of male Mongolian gerbils (Meriones unguiculatus) were examined. After undergoing gonadectomy, castrated males were implanted with empty capsules or capsules containing T; sham-operated males were implanted with empty Silastic capsules. Subsequently, each male was paired with a pregnant female, and after delivery, families were observed 15 min/day for 20 days. Gonadectomized males without T spent more time in contact with, huddling over, and licking pups than did either sham-operated males or gonadectomized males with T. When given a choice between nest sites and displaced pups, females and males with low T preferred pups, whereas intact males and castrated males with T preferred nest sites. The findings are consistent with E. D. Ketterson and V. Nolan's (1994) hypothesis implicating T in mediating trade-offs between parental and sexual effort.