Why is it that some species seem to be particularly attentive parents while others leave their young to fend for themselves? For years, scientists have believed one of the major drivers is experience — an animal raised by an attentive parent, the argument goes, is likely to be an attentive parent itself.
A Harvard study is challenging that idea, and breaking new ground by uncovering links between the activity of specific genes and parenting differences across species.
Led by Professor of Organismic and Evolutionary Biology and Molecular and Cellular Biology Hopi Hoekstra and postdoctoral researcher Andrés Bendesky, the study found not only that different genes may influence behaviors in males and females, but also that the gene for the hormone vasopressin appears to be closely tied to nest-building behavior in parenting mice. The research is described in an April 19 paper published in Nature.
“This is one of the first cases in which a gene has been implicated in parental care in a mammal,” Hoekstra said. “In fact, it’s one of the few genes that has been implicated in the evolution of behavior in general … but what I think is particularly exciting about this is the idea that, while in many systems we know that parenting behavior can be affected by your environment, we now have evidence that genetics can play an important role as well.”
“We know there is variation between species in how much parental behavior they provide for their young,” Bendesky said. “It’s not that one is better or worse, they’re just different strategies … but before our study we had no idea how these parental behaviors evolved, whether there was one gene that mediates all of the differences in behavior, or if it was 10 or 20.”
The idea for the study grew out of differences in mating systems researchers had observed between two sister mouse species — Peromyscus maniculatus, also known as the deer mouse, and P. polionotus, the oldfield mouse.
“Like many rodents, the deer mouse is what we refer to as promiscuous, meaning both males and females mate with multiple individuals,” Hoekstra said. “Often when you genotype a litter, you will find pups from multiple fathers.”
The oldfield mouse, by comparison, is monogamous, so all the pups in a litter are sired by one father.
“It’s been widely documented that these mice have different mating systems,” Hoekstra said. “When Andrés joined the lab, he was interested in asking the question: Do those differences translate into differences in parental care?”
Bendesky first created a behavioral assay that tracked the behavior of males and females of each species and measured how often they engaged in parental behavior such as building nests and licking and huddling their pups.
In general, the data showed that females of both species were…