Infidelity in Nature: A Lion’s Story

By Devin Zingsheim

Lion by Devin ZingsheimWhen people think of mating, especially in the case of humans, they often think of one man marrying and mating with a single female. While this provides a nice image of mating, it is not always true. In the case of humans, both males and females may stray from this image and mate with other individuals. For example, a female in a relationship may become attracted to and mate with someone she finds exciting, like a rebel. These exciting individuals are the outsiders because they exist outside the female’s main relationship. But this is only in the human species – Could this observation hold true in another species, like lions?

As most people know, lions live in groups of animals, called prides. Prides often consist of between one and three dominant males and several females. Females of one pride typically do not co-mingle with members of other prides. This fact means that typically in a pride, the dominant males do all the mating and father all of the cubs born into their pride. However, as with humans, could there also be exceptions in lions?

Martha Lyke of Northeastern Illinois University, Jean Dubach of the Wildlife Genetics Lab at Loyola University Medical Center, and Michael Briggs of the African Predator Conservation Research Organization investigated breeding behavior in lions. These researchers noticed that field observations recorded females of prides residing in the Etosha National Park in Namibia interacting with outsider males. Outsider males can be from other prides or they can be rebels without a pride. This is unique because past studies focusing on lions of the Serengeti revealed that females seldom interact with other prides. These observations led the researchers to three main hypotheses. First, they thought that this mingling with outside males could lead to mating and eventually births. They also thought that females might mate with more than one male, potentially leading to cub siblings with different fathers. Lastly they thought prides with fewer males would be at greater risk for these illegitimate births because the male is not around enough to drive the outsider males away.

To find the answers to the three questions the researchers had, they set up a study in Etosha National Park. This national park has a program in which every lion that resides in the park is branded for monitoring. At the beginning of the study, the researchers took observations of every lion spotted and its interactions with other lions. Lions that were observed spending a lot of time with one another in a territory were considered a pride. This then allowed the researchers to identify when and if females interacted with outsider males. After identifying prides, the researchers gathered blood and tissue samples for analysis. DNA analysis indicated the parents of any cubs within the prides.

Observations led to the identification of 11 prides containing 102 lions. Prides on average contained 10 individuals and had a roughly 2:1 adult female to male sex ratio. Surprisingly, only 55% of the 164 DNA samples collected came from the 11 identified prides and a whopping 41% of cubs sampled were illegitimate and had outsider males as their fathers. Interestingly, the researchers found that these cubs fathered by non-pride males came from only five of the prides, four of which had an unusually high female to male sex ratio. Additionally, the researchers also found four cases where litters of cubs had different fathers!

These results provide a lot of new and interesting insights into the sexual behavior of lions. Evidence was found to support all three of the researchers’ hypothesis. They found that females do give birth to young whose fathers are not part of the pride and that mixed paternity does occur in this population. They also found that prides with fewer males did have cubs born to males from outside the pride. This might be due to the fact that there are fewer pride males around to protect and drive away outside males. Additionally, with fewer males around, females may want to seek out other males to ensure they get to reproduce. This study has found evidence that there may be a lot more to sexual behavior in lions than meets the eyes. It has shown that, like human females, lionesses may be tempted to run off and mate with that exciting rebel outsider male.

Works cited
Lyke, M., Dubach, J., & Briggs, M. (2013). A molecular analysis of African lion (Panthera leo) mating structure and extra-group paternity in Etosha National Park Molecular Ecology, 22 (10), 2787-2796 DOI: 10.1111/mec.12279

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