UTA biologist: Do chunky monkeys woo more mates?

Biologist investigates causes of seasonal weight gain in male squirrel monkeys

Monday, May 02, 2022 • Linsey Retcofsky : Contact

A Brazilian squirrel monkey sits on a branch, high among jungle trees. " _languageinserted="true
Photo courtesy of Claire Meuter of Cal Lutheran.

An evolutionary biologist at The University of Texas at Arlington is studying seasonal weight gain in male squirrel monkeys to determine its relationship to the species’ potential to sire offspring.

The National Science Foundation has awarded JC Buckner, assistant professor of biology, a four-year grant to study the Brazilian primates’ genetic traits and how they impact sexual selection.

During their brief mating season, male squirrel monkeys gain weight. Researchers think it is likely that the individuals who add the most pounds have the most reproductive success. That may occur because female squirrel monkeys find them more attractive than their thinner competitors.

Through DNA analysis, Buckner will investigate if weight gain is a sign of genetic quality to females who may be seeking a healthy mate. If packing on the pounds correlates with reproductive success and healthy genes, Buckner said it is likely that females are actively selecting the best parent for their offspring.

Simultaneously, her lab will look for alternate causes of weight gain. She hypothesizes that additional mass may help hopeful fathers challenge competing males and gain access to females. If this is true, then females would be viewed as playing a more passive role in mate selection.

JC Buckner, assistant professor of biology" _languageinserted="true
JC Buckner

At a time when biodiversity is in decline worldwide, basic biological research is necessary to further scientists’ understanding of species adaptability and survival, Buckner said.

“Humans and wildlife are increasingly affected by climate change and habitat degradation, which contribute to disease, novel stressors and population decline,” Buckner said. “Basic research like this is important to our understanding of the evolution of sexual signals and how they are used by species to adapt, reproduce and survive.”

Buckner’s investigation is funded by a collaborative grant awarded to UTA, California Lutheran University (CLU) and the University of California, Los Angeles (UCLA). Anita Stone, CLU assistant professor of biology, will spend four summers conducting field research in the eastern Amazonian forest. At UCLA, biological anthropologist Jessica Lynch will conduct paternity tests on biological samples from the baby monkeys that are born.