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Invasive shrimp species found in Wales

Cardiff, Wales -- British environmentalists say an invasive "killer" shrimp that feeds on native counterparts, young fish and insect larvae has been detected in Wales.

The predatory Dikerogammarus villosus can have serious impacts on the ecology of habitats it invades and can cause extinctions, the BBC reported.

Dubbed the killer shrimp by biologists for its voracious appetite, it often kills its prey and leaves it uneaten.

Originally from the steppe region between the Black Sea and the Caspian Sea, D. villosus, which can grow to be much larger than native freshwater shrimp, has been spreading across Western Europe for 10 years.

Scientists say evolution shapes ecology

Tallahassee -- U.S. scientists say an experiment with two populations of guppies shows that evolution's influence on ecology can be as great as the converse.

Professors Joseph Travis of Florida State University and David Reznick of the University of California-Riverside said they studied guppies who evolved to live in upstream communities of Trinidad, and genetically distinct guppies who evolved to live downstream.

The researchers said that because upstream guppies have fewer predators, they grow slowly and larger, reproduce later and less, and die older. In contrast, downstream guppies live where predators thrive, so that downstream guppies grow rapidly and smaller, reproduce quickly and die younger.