Sex differences in parental response to offspring begging are associated with pair bond strength across birds

What is it about?

One of the most contentious evolutionary conflicts is how much food parents feed their young. Offspring want their parents to feed more, while parents may want to do the minimum to keep their offspring alive. Offspring can beg to ask for more food—but how much begging is rewarded can depend on who is listening. While both parents benefit from feeding offspring, each would benefit from their partner shouldering more of the burden of care, leading to sexual conflict. In other words, mom prefer dad does more work, while dad prefers the opposite. Whether parent-offspring communication (begging) is influenced by sexual conflicts is not understood. To determine if the sexes differ in their response to begging, we looked at data from 31 bird species. We found that mating system impacts how much parents listen to their young. In species with long term stable bonds and/or low promiscuity, and thus lower sexual and paternal-offspring conflict, fathers respond more to begging than mothers do. The opposite holds for species that change partners between breeding bouts and/or have high promiscuity: females respond more to begging, perhaps compensating for males’ lower responsiveness. These results suggest that sex differences in parent-offspring communication can emerge from sexual conflict.

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