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Stanford survey suggests climate change has reduced the presence of invasive Argentine ants

Stanford biology professor Deborah Gordon at a valley oak.
Aug 5 2021
Faculty, Fellow, Research, Stanford

In 1993, Stanford University biology professor Deborah Gordon and her first graduate student, Katy Human, began a survey of ants at Stanford’s Jasper Ridge Biological Preserve. Nearly 30 years, four more graduate students and scores of volunteers later, that survey continues on – and has recently yielded a surprising result.

“From 1993 until the time I was doing my dissertation work, about 2000, it seemed as if Argentine ants were marching across the preserve, taking out native ants along the way,” said Nate Sanders, one of Gordon’s former graduate students who led the survey in the late ’90s and is now a professor of ecology and evolutionary biology at the University of Michigan. “Now, with an additional 20 years of data, we see the story is more complex.”

That additional data, detailed in a paper published Aug. 3 in Ecology, has revealed that the distribution of Argentine ants in Jasper Ridge has actually receded, and further analysis suggested that climate change was a significant factor in this change. The researchers also found that, over the span of the survey, overall native ant diversity increased and some native ant species have expanded their distributions.

However, the researchers caution against making this an optimistic story about the effects of climate change, which still overwhelmingly poses severe threats to native species. But their work does stand as a testament to the importance of long-term research and what it takes to produce that work.

“To keep this survey going, there have been over a hundred participants over the years,” said Lisa Couper, the latest Stanford graduate student to study the survey and lead author of the paper. “Long-term ecological datasets are really rare and, as far as we know, this is one of the longest-running surveys of an ongoing biological invasion.”

Study lead author, Lisa Couper, is a 2018 SGF Fellow.

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