University of Otago zoology researchers Dr Graham McCulloch and Professor Jon Waters have found New Zealand’s native stoneflies have changed colour in response to human-driven environmental changes, arguably providing the world’s most clear-cut case of animal evolution in response to change made by humans.
Dr McCulloch said they were looking at the rapid evolution of Zelandoperla stoneflies, which historically mimicked the poisonous Austroperla stoneflies to protect themselves from predators.
Austroperla produce cyanide to deter potential predators, and to advertise its toxicity, it has high-contrast black, white and yellow markings, reminiscent of wasp colouration.
Following extensive deforestation across New Zealand, the Austroperla and native birds disappeared, and the Zelandoperla stopped mimicking the Austroperla and started turning a brighter brown colour.
Dr McCulloch said the darker colouration actually made them stand out more to predators.
"You’re basically just standing out for no reason.
"So that’s why we’ve seen these quite rapid evolutionary shifts to a brighter colour.
"Normally, when you think about evolution, you think of this really slow, gradual process occurring over millions of years.
"But what we’re looking at is human-driven evolution, and the really cool thing about that is, it occurs really quickly — like within centuries or decades."
Prof Waters said scientists had long wondered whether humans were causing evolutionary changes in natural populations.
The most well-known example of evolution caused by humans was the peppered moth population in the United Kingdom, which changed colour in response to industrial pollution in the 1800s.
But Prof Waters said even that case had been considered controversial.
This new study showed how humans had changed the way native species interacted.
Dr McCulloch said humans had disrupted ecological interactions between species that evolved over millions of years, but some of our native species were resilient enough to overcome this.
"The research results are crucial.
"When we think of things like climate change happening, we need to know how our native fauna are responding.
"This is a really nice case example of the fact that our fauna can adapt to these changes.
"And they can evolve a lot quicker than we thought. It can happen over a researcher’s lifetime."
