New Zealand’s native stoneflies have changed colour in response to human-driven environmental shifts

Back in the 1800s, during the Industrial Revolution, pollution darkened tree barks and peppered moths developed darker colours that allowed them to blend in and evade predators. While this controversial case has been debated among scientists at length, new research has provided an intriguing parallel to this classic example of the effect human activity can have on other species.

New research from the University of Otago has uncovered a striking example of rapid evolution in New Zealand's native stoneflies, which have changed colour in response to deforestation caused by human activity. Published in Science, the study is one of the most definitive cases yet of animal evolution driven by human-driven environmental changes, the researchers believe.

Professor Jon Waters, a zoology expert and co-author of the study, explains how deforestation altered the stoneflies' colouring. “In natural, forested regions, one stonefly species has evolved ‘warning’ colours, mimicking the appearance of a poisonous species to deter predators. But with forest removal, the poisonous species disappeared, eliminating the need for mimicry. As a result, the stonefly in deforested areas evolved into a different colour altogether.”

Dr Graham McCulloch, another co-author of the study, highlights the adaptability of some native species in the face of these rapid environmental changes. “Our study shows that some species have the resilience to adapt to human-caused changes, even when the shift is abrupt,” says Dr. McCulloch.

What was particularly fascinating was that stonefly populations in separate deforested areas independently evolved similar colour changes, suggesting that evolution can be a somewhat predictable process.

While this discovery is a hopeful example of adaptation, the research also underscores the intricate and delicate balance in ecological interactions that can be disrupted by deforestation.