When a good insect father pairs with a bad female, he risks being exploited by her for childcare and bears the ultimate cost by dying young, said a study carried out with burying beetles.
The study also shows that bad parenting creates bad parents-to-be, while well-cared larvae turned into high quality parents, said the study published in the journal eLife.
“Parents obviously play a huge role in determining the characteristics of their offspring,” says Rebecca Kilner from the Department of Zoology at the University of Cambridge. “The aim of our study was to investigate non-genetic ways.”
This is important because non-genetic inheritance could speed up the rate at which animal behaviour evolves. Whether examining mothers or fathers, the research team found that individuals that received no care as larvae were less effective at raising a large brood as parents, and died younger.
In contrast, high quality care not only produces a larger brood, but individual offspring with a higher mass. “We found that parental care provides a mechanism for non-genetic inheritance. Good quality parents produce offspring that become good parents themselves, while offspring that receive poor parenting then become low quality parents,” she says.
However, the team also found that offspring pay a cost for receiving high quality care, because it makes them vulnerable to exploitation if they pair up with a lower quality partner. This may explain why animals often choose a mate that is willing to put in a similar amount of effort as them as a parent. In this way, they are less vulnerable to exploitation.
The burying beetle, Nicrophorus vespilloides, uses the carcass of a small vertebrate such as a mouse as an edible nest for its young. As its name suggests, a breeding pair buries the carcass and preserves it with an antibacterial secretion. The mother lays eggs nearby in the soil, and the larvae crawl to the carcass when they hatch. Although the larvae can feed themselves, they also beg both parents for partly-digested food from the carcass.
In the current study, when males were paired with females that had received no post-hatching care as larvae, they had significantly shorter lives than those whose partners had received more care.
The most likely explanation is that males with low quality partners put more effort into parental duties to compensate for the shortcomings of their mate, and paid the price by dying younger.