In the 1990s, two species of endangered stickleback fish went extinct and were replaced by a hybridized species in Enos Lake on Vancouver Island. Photo by Ernie Cooper/UBC

VANCOUVER, British Columbia, Feb. 23 (UPI) -- New research suggests human impact may encourage the disappearance of younger species, speeding up the process of evolution.

Researchers from the University of British Columbia arrived at their conclusion after investigating the disappearance of two similar threespine stickleback fish species at Enos Lake on Vancouver Island.


In the mid-1990s, humans introduced crayfish to the lake. In the three years that followed, scientists watched as two species of endangered threespine stickleback fish went extinct.

The heightened competition for resources, caused by the introduction of the crayfish, encouraged interbreeding. The two endangered species gave way to a hybridized species. Scientists call the phenomenon reverse speciation.

Recently published in the journal Current Biology, the latest study by UBC researchers highlights the ecological consequences of accelerated evolution and reverse speciation.

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

Before their disappearance, one of the fish species preyed mostly on zooplankton and lived at the center of the lake, while the other lived near the shore and ate insect larva. Their hybridized replacement sticks to the edges of the lake and eats more large insects, allowing the larva of smaller insects to develop and hatch larger populations.

Researchers say Canada's ecosystems are especially susceptible to reverse speciation.

"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," explained Rudman.

"This type of evolution, known as reverse speciation, happens remarkably quickly and can cause alterations to the ecology of the ecosystem," he continued. "It means we need to consider evolution in our conservation efforts."