Rapid Evolution Triggered by Environmental Change: The Fate of Our Fisheries

Evolution occurs faster than you might expect. Instead of hundreds or thousands of years, researchers have found that environmental changes can drive hard-wired evolutionary changes in a matter of generations--at least when it comes to soil mites.

Researchers discovered that soil mites in the lab demonstrated significant genetically transmitted changes in a mere 15 generations. In fact, some of the mites took twice as much time to reach adulthood.

That's not to say that the findings mean that all creatures will evolve as rapidly. However, the research does have important implications in areas such as disease and pest control. It can also provide insight into fisheries management since overfishing causes rapid changes in populations. In fact, a recent study revealed that applying heavy pressure to fish species causes smaller fish that produce fewer eggs to emerge.  This, in turn, can cause fisheries to collapse.

In this latest study, the researchers worked with soil mites collected from the wild and raised them in 18 glass tubes. They then removed 40 percent of adult mites every week from six of the glass tubes, a similar proportion of juveniles from another six tubes and left the last six tubes alone.

"We saw significant evolutionary changes relatively quickly," said Tom Cameron, lead author, in a press release. "The age of maturity of the mites in the tubes doubled over about 15 generations, because they were competing in a different way than they would be in the wild. Removing the adults caused them to remain as juveniles even longer because the genetics were responding to the high chance that they were going to die as soon as they matured. When they did eventually mature, they were so enormous that they could lay all of their eggs very quickly."

The changes weren't short-term, either. The researchers separated short-term ecological responses--such as the formation of smaller mites due to a lack of food--and hard-wired evolutionary changes by placing the mites from different treatments into a similar environment for several generations. In the end, the differences in the populations persisted.

This finding in particular could spell bad news for fisheries. Even if fishing pressures were lessened, it's likely that fish populations would continue to remain stunted and produce fewer eggs. Currently, the size at which cod mature in the North Sea is about half that of 50 years ago, which has helped aid in the collapse of the cod population.

"The big debate has been over whether this in an evolutionary response to the way they are fished or whether this is, for instance, just the amount of food in the sea having a short-term ecological effect," said Tim Benton, a professor at the University of Leeds' Faculty of Biological Sciences,  in a press release. "You can't just try to bring the environment back to what it was before and expect everything to be normal."

The study was published in the journal Ecology Letters.