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By Kati Moore, MEM ‘16
Nicholas School Student Blogger and Communications Assistant
DURHAM, N.C. – In the Kuruman River Reserve in the Kalahari Desert of South Africa, groups of meerkats have become accustomed to the presence of researchers who study their behavior and track their movements.
Duke doctoral student Kendra Smyth has spent much of her time in this reserve studying how meerkats’ social position in their matriarchal clans affects their health. An immunologist by training, Smyth looks at how hormone levels in meerkat mothers affect their offspring’s immune system functioning later in life.
Smyth is a fourth year doctoral student in Duke’s University Program in Ecology.
In meerkat society, she explains, females rule. Each group of meerkats, which can include anywhere from three to forty individuals, has a dominant female who has a monopoly on reproduction. Subordinate females help raise the matriarch’s offspring, producing milk to feed the babies and later teaching them how to hunt and avoid scorpion stings.
If any subordinate females become pregnant, the dominant female may exile them from the group or kill the offspring after they are born. However, if a subordinate female times her pregnancy just right, giving birth [just after] the dominant female does, she may be able to successfully reproduce.
Dominant females are very aggressive, partly due to their high levels of androgens, a hormone typically studied in males. In 2015, Smyth published a paper in Behavioral Ecology showing that dominant females also have more parasites – a proxy for measuring the immune system – than do other group members, indicating that their immune systems are weaker.
As part of her dissertation research, she followed up that study by working with her doctoral advisor, Christine Drea of Duke’s Department of Evolutionary Anthropology, to block androgens in dominant females.
Smyth then compared the immune responses of their offspring to those of normal dominant and subordinate females. She found that the offspring that were exposed to less androgen in the womb had stronger immune systems, indicating that there is a trade-off between being more aggressive and having a better immune response.
Smyth recently received a Doctoral Dissertation Improvement Grant from the National Science Foundation to follow the offspring from the three groups of females as they go off on their own to form their own family groups.
“This is an understudied transition, but it is a critical time in an animal’s life,” she says.
When females mature, the dominant female in the group may let them stay to assist in raising her pups, she adds, “but because the likelihood of a subordinate female achieving dominant status in her natal group is low, it may be in her best interest to move on and find another spot to set up.”
Because meerkats are social animals, leaving the group is very stressful. As they travel through new territories, they may be exposed to new predators or novel diseases or parasites, leaving Smyth and other researchers to wonder if exiled meerkats that are better able to withstand disease and cope with stress are more successful at forming their own groups.
Until recently, the researchers studying the meerkats at the Kuruman River Reserve were not even sure that meerkats survived after setting off on their own. By placing GPS tracking collars on the animals, however, researchers can now track meerkats as they set up their own family groups.
“We just bring our computer close to a meerkat wearing a collar, and we can download all of her movement data. It’s a really neat system,” Smyth says.
Developing a better understanding of meerkat movements may have conservation implications for other mammals that disperse in similar patterns, she notes. “Meerkats aren’t endangered, but they’re potentially a great model for animals that are.”
Smyth received her master’s degree in animal science with a focus on immunology from University of Maryland at College Park.