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May 26, 2024

On repeat: Biologists observe recurring evolutionary changes, over time, in stick insects

Posted by in category: evolution

“If you frame it as an either/or question, it’s too simplistic,” says Utah State University evolutionary biologist Zachariah Gompert. “The answer isn’t ‘completely random’ or ‘completely deterministic and predictable.’ And yet, examining short time scales, we can find predictable, repeatable evolutionary patterns.”

Gompert and colleagues report evidence of repeatable evolution in populations of stick insects in the May 24, 2024, online edition of the American Association for the Advancement of Science’s journal Science Advances. Collaborating authors on the paper include Gompert’s long-time collaborator Patrik Nosil and other researchers from France’s University of Montpelier, Brazil’s Federal University of São Paulo, the University of Nevada, Reno and Notre Dame University. The research is supported by the National Science Foundation and the European Research Council.

The team examined three decades of data on the frequency of cryptic color-pattern morphs in the stick insect species Timema cristinae in ten naturally replicate populations in California. T. cristinae is polymorphic in regard to its body color and pattern. Some insects are green, which allows the wingless, plant-feeding insect to blend in with California lilac (Ceanothus spinosus) shrubs. In contrast, green striped morphs disappear against chamise (Adenostoma fasciculatum) shrubs.

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