Sunday Times 2
And the award for the best dad goes to…the owl monkey
Study found all the male and female owl monkeys that cared for the young were the infants’ biological parents, suggesting the species never cheated
True monogamy is rare in the animal kingdom – even in species that appear to mate for life, tests have revealed cheating is common place.
However, a new study by University of Pennsylvania has found Azara’s owl monkeys, buck this trend because they are ‘unusually faithful.’
The investigation of 35 offspring born to 17 owl monkey pairs turned up no evidence of cheating, and the male and female monkeys that cared for the young were the infants’ true biological parents.
Researchers paired behavioural field observations with genetic tests to see whether the 'social' mothers and fathers of infant monkeys were the biological parents. By examining 14 different regions of the genome, the analysis strongly suggested owl monkeys were completely faithful (CC BY-SA 2.0 'Owl monkey family' by mikemaehr4)
An additional analysis of 15 pair-living mammals found a strong connection between a species’ faithfulness and how much of a role the males took in caring for their young.
‘Our study is the first of any primate species, and only the fourth for a pair-living mammal, to show genetic monogamy, or real faithfulness, between partners,’ said study author Eduardo Fernandez-Duque, an associate professor in Penn Arts and Sciences’ Department of Anthropology.
‘Paternal care in owl monkeys now makes sense. The males are making a huge investment in their own offspring.’
As part of the Owl Monkey Project, the Penn evolutionary anthropologists have been studying a population of primates in Argentina’s Chaco region for 18 years.
Previous research found male and female owl monkeys form strong pair-bonds and that males contribute significantly to raising young by carrying them on their bodies, playing with them and feeding them solid foods.
Although the species was known to be socially monogamous, no one had tested whether the species was genetically monogamous – in other words, whether there were any cases of females reproducing with a male other than her mate, a behaviour known as ‘extra-pair paternity’.
To test this, the researchers paired behavioural field observations with genetic tests to see whether the ‘social’ mothers and fathers of infant monkeys were the biological parents.
They collected samples from 128 individual monkeys living in 29 groups or as solitary ‘floaters.’ This set included genetic samples from 35 infants born to 17 reproducing pairs.
By examining 14 different regions of the genome, the analysis strongly suggested that owl monkeys were completely faithful. Researchers found no evidence of extra-pair paternity.
‘In the 18 years of the Owl Monkey Project, we never witnessed a little sneaky copulation with a neighbour, or that one partner dashed off for some time,’ Fernandez-Duque said.
‘So in that sense we were not very much surprised by our results. But true genetic monogamy is very rare. We would not have been surprised if there had been at least one non-pair infant, but there were none.’
Indeed, no other robust study of primates has demonstrated genetic monogamy. It has been shown in only four other mammal species, including coyotes and the California mouse.
Because the researchers were interested in how genetic monogamy has evolved and the conditions under which it occurs, they went on to perform an analysis of 15 mammal species that have been shown to live in socially monogamous pairs and for which paternity studies have been conducted.
In addition to the owl monkeys, this group included birds, rodents and canines.
The results of this broader investigation found that species in which males contribute significantly to infant care were more likely to be genetically monogamous.
They also found an association between the strength of the bond between mates – the percentage of time the male and female spent together – and low levels of extra-pair paternity, but this connection was not as strong.
Though their results underline the presence of a connection between intense male care for young and faithfulness, the researchers say they cannot, yet, tell which condition gives rise to the other.
‘Male care is surely not the only factor explaining genetic monogamy,’ co-author Maren Huck added. ‘Some of the species that show male care have, due for example to their foraging habits, much more opportunities for seeking extra-pair copulations than owl monkeys.’
The team also noted that being a good dad can also be a mating strategy in and of itself; females might be attracted to males that appear to be good dads.
These findings in the owl monkey and other species can begin to help explain the evolution of pair-bonds in another primate species: human beings.
‘Pair bonding, love if you want, is prevalent in all human societies, whereas fathering is much more variable,’ Fernandez-Duque continued.
‘The owl monkey story is suggesting that, under very specific ecological settings, this preference for each other leads to the pair spending a lot of time in close proximity, thus facilitating paternal care and increasing paternity certainty. Genetic monogamy is the result.’
The study will be published in Proceedings of the Royal Society B: Biological Sciences.
© Daily Mail, London
| MONOGAMY IN OWL MONKEYS
Researchers paired behavioural field observations with genetic tests to see whether the ‘social’ mothers and fathers of infant monkeys were the biological parents. They collected samples from 128 individual owl monkeys living in 29 groups, or as solitary ‘floaters.’ This set included genetic samples from 35 infants born to 17 reproducing pairs. By examining 14 different regions of the genome, the research team’s analysis strongly suggested that owl monkeys were completely faithful. |