January 11, 2013 12:03 pm
Mice fathers like to mess around. Fatherhood doesn’t come naturally to these polygamous males, who would prefer to be out on the prowl for a new mate rather than tending to mouse pups in the nest. Female mice, however, have tricks for encouraging the often-absentee father of their offspring to care and get involved in child-tending, The Scientist reports.
When mother mice need help, research published in Nature Communications showed, they use a mix of ultrasonic vocalizations and odor cues to convince males to pitch in. In the lab, normally male mice kept in cages with their offspring tend to ignore the babies for the first 3 to 5 days, but eventually break down and start showing signs of parental care.
To figure out whether it’s the pups or the mothers who inspire males to care, researchers separated fathers from their families, either alone or with their female counterpart, for 3, 5 and 10 minutes in a connected but barred chamber. When co-housed with females, the males took up their fatherhood duties when the door lifted and they were reunited with their pups. But when kept alone, the males ignored the pups and, like a bachelors returning to their pads, actually showed preference for returning to the empty, now accessible chamber,.
The mother, the researchers suspected, must be playing a role in influencing male behavior. They conducted experiments placing mothers in sound proof/smell proof boxes, and in boxes with open lids. In the former case, males ignored their offspring. In the latter, they took up baby tending in the absence of their mate.
The researchers captured the mother’s ultrasound vocalizations during her period of captivity, and when they played the recordings back to father, 60 percent retrieved their pups, compared to zero in the control group. Mothers also release maternal pheromones when they’re separated from their pups, the researchers found, which inspired 55 percent of the males to comply with their wishes. When those influential smells and sounds combined, 67 percent of the males responded. Deaf and anosmic (smell-blind) males were immune to the female’s persuasions.
“It seems as if the mother communicates her fear about the loss of her children to the father to make him attentive and motivated to be a good father and carry the children back in case he finds them by accident,” the researchers told The Scientist.
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