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Humans Speeding Up Evolution: Introduction Of New Species Disrupts Ecosystem

Feb 27, 2016 02:13 PM EST
Crayfish introduced to Enos Lake on Vancouver Island caused the extinction of two species of threespine stickleback fish living in the lake.
(Photo : Flickr: coniferconifer)

Humans may be speeding up the otherwise slow process of evolution by introducing new species to unfamiliar areas, a recent study from the University of British Columbia (UBC) revealed. Researchers came to this conclusion after investigating the disappearance of two similar endangered threespine stickleback fish species at Enos Lake on Vancouver Island.

"When two similar species are in one environment, they often perform different ecological roles," Seth Rudman, a Ph.D. student in zoology at UBC, explained in a news release. "When they go extinct, it has strong consequences for the ecosystem."

The fish had existed in the lake for thousands of years, with one living in the middle of the lake eating mostly zooplankton and the other living closer to shore, where it primarily ate insect larvae. However, just three years after crayfish were introduced to the ecosystem in the mid-1990s, the stickleback fish disappeared.

It is believed that the presence of crayfish increased resource competition and encouraged inbreeding. Eventually, the two species of stickleback fish gave way to a hybridized species. This phenomenon is known as reverse speciation. 

Consequently, the new stickleback fish does not perform all of the functions as its predecessors. For example, the hybrid spends more time near the shore of the lake and eats more large insects, so the number of small insects coming out of the lake has increased. Researchers have also found that the leaves that fall into the lake do not decompose as quickly.

Younger species are prone to reverse speciation, and as humans continue to alter natural environments, it is becoming a much more common phenomena. 

"Much of Canada's biodiversity, particularly fish in lakes and rivers, are considered to be 'young' species that formed in the last 12,000 years or so," Rudman added in the university's release. "This type of evolution, known as reverse speciation, happens remarkably quickly and can cause alterations to the ecology of the ecosystem. It means we need to consider evolution in our conservation efforts."

Their study was recently published in the journal Current Biology

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