In many species males put a lot of effort into caring for offspring that are not their own. At first glance this makes no sense at all because natural selection should design males to only care for offspring that carry their genes. However, males are much more astute than we might think and maximise their care according to how likely it is that females are unfaithful whilst judging whether caring will reduce the number of offspring they can have in the future.
“These are complex calculations that males are making and it has been difficult to measure things correctly, but looking across species has helped us work out what is going on”, says Charlie Cornwallis, researcher at the Department of Biology, Lund University, Sweden.
The researchers conducted a meta-analysis of 62 studies across 48 different species including insects, fish, birds and mammals. Although parental care is highly variable across these species, the researchers were able to explain why sticking around to care is the better choice for some males that have been usurped: Males tend to be more accepting of offspring fathered by other males in species where the risk of cuckoldry is generally low or caring does not harm their reproductive success.
“This to me shows the strength of natural selection, with its footprints clear in species as different as burying beetles, which care for young over a few weeks by regurgitating dead mice, to humans that spend years providing for their children”, Cornwallis says.
The study opens up an interesting path to more research in the area. Now that the researchers know what factors are important they can design studies to further test their findings and predict what males will do in species that have not yet been studied.
“Our study includes data from all species looked at so far and so provides a future guide to the types of species and experimental cues that are best to examine when conducting more detailed studies of paternal care”, Cornwallis says.
The study, Why do Cuckolded Males Provide Paternal Care?, has been published in PLOS Biology. http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001520