Biology

El Niño drought reveals survival advantage of monkeys with strong stress response

Two white-faced capuchin monkeys were spotted holding hands in Guanacaste, Costa Rica. Credit: Susan Perry

Costa Rican capuchin monkeys that experienced a stronger physiological response to mild drought are better suited to survive even extreme drought, researchers found in a new UCLA-led study.

Most research on wildlife and humans focuses on the damage, or “wear and tear,” that stress responses cause to systems. But in this new study published in the journal Science Advances, a team of researchers explores the adaptive nature of stress responses in wild primates and how a stronger stress response can help when faced with catastrophic events. I tried to investigate.

“We’re looking at how stress responses adapt to help these individuals overcome greater challenges,” said Susan Perry, an evolutionary anthropologist and field primatologist at UCLA and co-author of the study. I wanted to understand if it would be useful.”

Because no experimental design exists that allows the same stressor to be applied to all individuals in a population, researchers have used natural experiments, specifically the severe El Niño drought, to investigate the relationship between hormonal responses to this extreme stressor and survival outcomes. investigated the relationship. A photo of a capuchin monkey taken at the Lomas Barbudal Capuchin Monkey Project in Guanacaste, Costa Rica.

In Guanacaste, Perry and a team of researchers have been documenting the lives of monkeys for 35 years, studying their social behavior and survival strategies. For this particular study, Perry’s research group (including current and former graduate students and research assistants Eileen Godoy, Ashley Mensing, Julian Damm, and Colleen Gault) teamed up with University of Michigan researcher Jacinta Gault.・Collaborated with Mr. Beener and Ms. Sofia Carrera.

How a drought led to the discovery

The El Niño drought that spread across Central and South America from 2014 to 2016 was the largest in recent history, killing many monkeys. Disastrously for researchers who have studied monkeys and monkeys for years, Perry’s team used environmental conditions and samples collected six years ago to link endocrine stress responses and survival in albino monkeys. I was able to study the relationship between I came face to face with a capuchin monkey.

During the drought, the monkeys began to lose weight, their spines and rib cages were exposed, and their mothers refused to care for or nurse their infants, even abandoning them to forage for food. The monkeys, which typically babysit infants when their mothers are not present, also had no childcare responsibilities. Mortality rates rose sharply, especially among young children and older women. This was the only time in Perry’s long-term studies that these usually behaviorally flexible monkeys were unable to adapt to environmental stressors simply by changing their behavior (for example, changing their diet).

Monkeys' strong stress response helps them survive

A white-faced male capuchin monkey eats grass seeds during the dry season in Guanacaste, Costa Rica. Researchers have been documenting the lives of these monkeys for 35 years, studying their social behavior and survival strategies. Credit: Susan Perry

The researchers analyzed glucocorticoid levels in feces collected from 14 female monkeys that survived and 14 that died during the six years before the El Niño drought (2008-2013). Glucocorticoids are steroid hormones that regulate metabolism, inflammation, and the immune system.

What glucocorticoids in monkey feces reveal

The researchers found that monkeys that showed rapid increases in these stress hormones during mild droughts were more likely to survive severe El Niño droughts than monkeys that had fewer stress responses. The findings were made while controlling for other conditions known to influence these hormone levels, such as pregnancy and time of day.

Now that they have a clearer picture of what adaptive stress responses look like in this species and population, Perry’s team is now looking into the origins and maintenance of individual differences in endocrine stress responses, and how these differences impact survival. You can begin to wonder whether or not.

The study also highlights the value of long-term research in the face of climate change. As weather intensifies globally, longitudinal studies of how wild animals cope with changes in temperature, rainfall, and food availability will help improve which species, through learning and physiological flexibility. It could help us understand which species are able to adapt rapidly and which lack the ability to cope with large environmental changes over their lifetime. .

This knowledge is useful for conservation reasons. For example, a highly endangered animal population that cannot quickly adapt to change may need to move to a location with climatic conditions that match the environment in which the population evolved.

Further information: Sofia C. Carrera et al. “Stress reactivity in wild primates predicts survival during extreme El Niño droughts,” Science Advances (2025). DOI: 10.1126/sciadv.adq5020

Provided by University of California, Los Angeles

Citation: El Nino drought reveals survival advantage for monkeys with strong stress response (January 22, 2025) https://phys.org/news/2025-01-el-nio-drought-reveals- Retrieved January 22, 2025 from survival.html

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