Being the dominant member of a group comes at a cost – new research from Duke University highlights the strains that meerkat matriarchs experience while trying to maintain the dynamics of their societies.

To maintain their position as the dominant matriarch, the female meerkat in charge must keep close watch on her meerkat group – scolding and punishing those who step out of line. Staying dominant means she is able to secure most of the breeding opportunities, producing more offspring and therefore achieving a greater genetic fitness. This is stressful for the matriarch, but not only is she stressed out, she’s also under attack from more parasites than the rest of her group too.

Kendra Smyth, from Duke University, studied meerkat societies in the Kuruman River Reserve in the Kalahari Desert of South Africa for two years. During this time she was able to sample the parasites of over 80 sexually mature meerkats, from 18 different social groups.

How does a researcher go about this? By collecting poo, of course. The parasites that Smyth analysed were internal parasites of the gut, and she was able to count the eggs of intestinal worms that the meerkats were hosting.

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It’s well documented that dominant individuals often have compromised immune systems. This can be due to a variety of reasons. The amount of stress that a dominant animal is under could take energy and resources away from maintaining the immune response to parasites. Or, the amount of contact that the dominant animal has with the rest of the group could increase the probability of contracting those parasites in the first place.

Either way, it’s another example of the game of costs and benefits in the animal kingdom. It’s beneficial for female meerkats to become dominant and secure more mating opportunities, but this comes at the cost of increased parasite load. Smyth’s results appear online this month in the Behavioural Ecology journal.

But why should we care about the amount of parasites a meerkat has anyway? “Parasites are a proxy for measuring the immune system,” said Smyth, who is a fourth-year grad student.

And wild-living meerkats can be a kind of proxy for humans. “Most of what we know about the immune system comes from laboratory mice living in unrealistic conditions,” Smyth said. “They’re housed singly in clean cages and they’re parasite-free. I’m not convinced that that’s how the immune system works when you put them in the natural world.”

“For any kind of species living in groups, like humans, it’s important to understand the dynamics of the spread of disease and which individuals might be susceptible,” she said.

reference
Smyth, K. N., & Drea, C. M. (2015). Patterns of parasitism in the cooperatively breeding meerkat: a cost of dominance for females. Behavioral Ecology, arv132.