Environmental change ‘triggers rapid evolution

By Mark Kinver
Environment reporter, BBC News

Changes to their surroundings can trigger “rapid evolution” in species as they adopt traits to help them survive in the new conditions, a study shows.

Studying soil mites in a laboratory, researchers found that the invertebrates’ age of maturity almost doubled in just 20-or-so generations.

It had been assumed that evolutionary change only occurred over a much longer timescale.

The findings have been published in the journal Ecology Letters.

“What this study shows for the first time is that evolution and ecology go hand-in-hand,” explained co-author Tim Benton, professor of population ecology at the University of Leeds, UK.

“The implicit assumption has always been, from Darwin onwards, that evolution works on long timescale and ecology works on short timescales.

“The thinking was that if you squash a population or you change the environment then nothing will happen from an evolutionary point-of-view for generations and generations, for centuries.”

Running wild

Prof Benton said that the soil mites experiment was set up to help shed light on whether the change in the size of harvested fish species, such as North Atlantic cod, was a result of an evolutionary change.

“The advantage of what we have done is that we have got free-running populations of organisms that do their own thing,” he told BBC News.

The team sourced soil mites from four UK locations and housed them in 18 tests tubes in a laboratory.

“Some of the populations were harvested, as per a fisheries management approach; juveniles were harvested from some tubes, adults from others, and other tubes we just left alone,” Prof Benton explained.

“Then we just looked to see what happened to their genetics, their life history and their population dynamics.

“We were all rather surprised to see how quickly they evolved in ways that you would not necessarily would have thought possible.

“The key result is that over the 20-or-so generations, their age of maturity almost doubled – that is an evolutionary effect.”

“That means that if the population is squashed for any reason then the population take longer to grow back and so you have all sorts of longer term consequences, it is not just a matter of what is happening to their life histories.”

Prof Benton said that the findings also showed that people involved in population management schemes, such as conserving endangered species etc, would have to take into account evolutionary factors, as well as ecological ones, as the result of environmental change.

He said: “For example, if you think about the challenges of climate change and nature reserves, where do you put the reserves?

“The way that animals move across the landscape, their dispersal behaviour is likely to evolve as a result of climate change.

“Do you put the nature reserves just 10 miles apart because that is how far the animals travel now, but in 50 years time, they might disperse five miles.”

Prof Benton added that evolutionary change added an additional pressure to population management schemes, namely that it was much more difficult to reverse than ecological change.

“Once you have lost the genes and the species has evolved into something different then it is very difficult to go back to what they were before.”

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