How Being Related Affects Teamwork in Male Lions

Compared to other big cats that prefer solitary lives, lions are very social and live in groups. Being part of a pride means having to cooperate, but sharing isn’t always easy—especially among male members.

In nature, males typically have to compete for everything from food to mates so the rules of cooperation can be hard to figure out.

Researchers from the Wildlife Institute of India and the University of Minnesota explored the way male lions work together. The results were published in the journal Scientific Reports.

For their work, the researchers studied the rare Asian lions that live in the Gir Forest of India. The lions live together as a single population.

Male lions typically team up into groups of two or more in order to gather resources as a group. These groups are called coalitions. Coalitions compete with other coalitions for resources like territories, food, and mates.

“Our previous research shows that males that cooperate and form coalitions fare better in reproductive fitness by being able to hold territories for longer than single males,” study lead author Stotra Chakrabarti, who was a postdoctoral research associate in the University of Minnesota’s College of Food, Agricultural and Natural Resource Sciences (CFANS) during the research, tells Treehugger.

“Coalition males, by working as a team, hold territories for durations almost double than that of single males, because teamwork helps such coalitions to defend their territories from intruding males as well as gain new territories by fighting off the residents.”

Holding territories for longer periods of time allows them to mate more often than single males which means they have more offspring.

Males in coalitions also cooperate while hunting prey which, Chakrabarti points out, is particularly relevant for the Asiatic lions in Gir because the males and females hunt in their same-sex groups.

“Coalitions/males hunt on their own. unlike in Serengeti/Ngorongoro where females do the bulk of hunting and males scavenge from such kills,” he says.

Family Matters

Researchers wanted to find out if cooperation was more likely to happen between related lions. In addition to monitoring lions, they collected blood, tissue, and hair samples to see if the male lions were connected.

Genetic analysis was difficult because the lions had experienced two population bottlenecks. These are events that cause extreme drops in a group’s population. They can be caused by habitat destruction, environmental disasters, hunting to the point of near-extinction, or other drastic occurrences. When something like this happens, the animals that remain have a very low level of genetic diversity because there are so few animals left.

But researchers were able to use records of mothers, offspring, and siblings to create a baseline panel. Then they compared male coalition partners to those records in order to understand how they were related to each other.

The researchers observed 23 male lions who belonged to 10 coalitions. They found those who were part of large coalitions of more than two members were typically brothers and cousins. But more than 70% of those that traveled in pairs were unrelated.

“Cooperation typically involves only related males when the coalition size is large. This is because in such large coalitions, the partners at lower ranks hardly get any chances to breed. Forgoing breeding opportunities is a huge evolutionary cost, unless by doing so one is helping a related partner,” Chakrabarti explains.

“Thus, subordinate partners can bear no-breeding costs only when they lose such opportunities to their brothers or cousins.”

Pros and Cons of Group Size

Sharing and cooperation is harder in larger groups because the resources have to be divided among a larger number of lions. Lower-ranking animals often don’t get the chance to mate in those situations.

“Forgoing mating opportunities is generally a severe evolutionary cost, unless in doing so you help related individuals,” Joseph Bump, co-author and associate professor in the Department of Fisheries, Wildlife, and Conservation Biology at CFANS, said in a statement. “As a consequence, this evidence supports a conclusion that large male lion coalitions are feasible only when all partners are brothers and/or cousins.”

Although these larger groups are more successful overall, lions fare better individually in smaller coalitions. That’s measured by the number of offspring they sire.

Researchers also found that related males were no more likely to have each other’s backs when fighting rivals than unrelated males.

Bump said, “This shows that kin support is not the only reason why males cooperate with each other, but kin support makes the cooperation even more beneficial.”