Invasive native crayfish hybrids discovered in Missouri

Scientists have discovered in Missouri that virile crayfish, Faxonius virilis, was interbreeding with a native crayfish, and giving rise to invasive-native crayfish that will lead to difficulties in future for the other marine life.

Researchers say that this interbreeding will potentially alter the native’s genetics, life history and ecology. According to scienitsts the virile crayfish is probably the widest-ranging native crayfish in North America and while it is a native species to North America, F. virilis is considered invasive in many parts of the U.S. because it quickly dominates new habitats when introduced – for example, by fishermen moving crayfish from one stream to another in a bait bucket, he said.

The virile crayfish was not native to the Current River watershed, however, and its presence could lead to declines in native crayfish species, he said.

Other invasive crayfish have disrupted the ecosystems they invade, Larson said. For example, the rusty crayfish is native to the Ohio River Basin but has invaded the waters of many other regions in the U.S. and Canada. It hybridizes with native crayfish, displacing them and reducing their reproductive output. It also consumes large quantities of aquatic plants and other invertebrates, undermining populations of some sport fish and crayfish species.

The virile crayfish was first detected in 1986 in the Current River, a pristine watershed, parts of which are administered by the U.S. National Park Service.

The researchers hoped to determine the extent of the F. virilis invasion by collecting and identifying mitochondrial DNA from environmental samples, an emerging approach for invasive-species surveillance known as “environmental DNA,” or eDNA. However, as they started collecting crayfish for genetic analysis to develop their eDNA sampling method, they discovered a surprising problem.

Researchers intially found that some of the native spothanded crayfish, Faxonius punctimanus, had mitochondrial DNA sequences that were aligning with invasive virile crayfish and later they found just the opposite wherein Some virile crayfish had the mitochondrial DNA of spothanded crayfish.

This meant that the two species were hybridizing with one another, researchers said. The discovery should come as a warning to those using environmental DNA to look for an invasive species in an area with closely related native species, said Larson, whose laboratory specializes in the use of eDNA.

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