Paternal Care in Biparental Rodents: Intra- and Inter-individual Variation

Abstract

Parental care by fathers, although rare among mmmals, can be essential for the survival and normal development of offspring in biparental species. A growing body of research on biparental rodents has identified several developmental and experiential influences on paternal responsiveness. Some of these factors, such as pubertal maturation, interactions with pups, and cues from a pregnant mate, contribute to pronounced changes in paternal responsiveness across the course of the lifetime in individual males. Others, particularly intrauterine position during gestation and parental care received during postnatal development, can have long-term effects on paternal behavior and contribute to stable differences among individuals within a species. Focusing on five well-studied, biparental rodent species, we review the developmental and experiential factors that have been shown to influence paternal responsiveness, and consider their roles in generating both intra- and inter-individual variation. We also review hormones and neuropeptides that have been shown to modulate paternal care and discuss their potential contributions to behavioral differences within and between males. Finally, we discuss the possibility that vasopressinergic and possibly oxytocinergic signaling within the brain, modulated by gonadal steroid hormones, may represent the "final common pathway" mediating effects of developmental and experiential variables on intra- and inter-individual variation in paternal care.

Fig. 1

Experiential effects on allopaternal and paternal responsiveness acting at different life stages in biparental rodents, as well as hormones and neuropeptides that have been implicated correlationally and/or experimentally. Bold text and thick arrows indicate cues or experiences routinely encountered during reproduction. Italicized text and dashed arrows indicate early-life influences that may differ across animals and contribute to stable inter-individual differences in (allo)paternal responsiveness. Non-italicized text and thin arrows indicate factors that might contribute to either intra- or inter-individual differences over a variable time span. T: testosterone; E: estrogen; AVP: vasopressin; OT: oxytocin; and Cort: corticosterone.