The genetic drivers of parental care behaviours are examined in a study of two mouse species published in Nature this week. The work identifies 12 genomic regions that affect parental care in these mice and demonstrates a role for the hormone vasopressin in one aspect of parental care, nest building.
Parental behaviour in mammals varies considerably among individuals, between sexes and across species, and can consist of an array of behaviours in mice including retrieving, huddling, nursing and grooming pups, and nest building. However, the genetic and evolutionary mechanisms that drive such behaviours remain poorly understood.
Hopi Hoekstra and colleagues studied two closely related species of mice, the promiscuous deer mouse (Peromyscus maniculatus) and the monogamous old-field mouse (Peromyscus polionotus). They show that the two species have large, heritable differences in parental behaviour. The authors use quantitative genetics to identify 12 genomic regions implicated in parental care, 8 of which have sex-specific effects, suggesting that male and female parental care behaviours may evolve independently. Some of these genomic regions seem to have broad impacts on parental care, whereas others affect only specific behaviours, such as nest building. The authors show that genetic changes that increase the levels of the hormone vasopressin are associated with less nest building. They also artificially manipulate vasopressin-releasing neurons in the hypothalamus, which, they find, modifies levels of nest building performed by the mice. The findings thus provide insights into the neurobiology underlying complex social behaviours such as parental care.