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Sensitive species not a species after all – how genetics solved the Arapahoe snowfly species mystery

Posted date: February 22, 2019

Scientific answers enable efficient use of conservation dollars

The Arapahoe snowfly was something of an enigma. This small stonefly, an aquatic insect important to trout and familiar to trout anglers, was thought to be rare and found only in a small area of northern Colorado. This limited presence earned it a Candidate species status under the Endangered Species Act and protections as a Sensitive Species on Forest Service lands. Researchers recently found that the Arapahoe snowfly is actually not a distinct species, but rather a hybrid of two other stonefly species. This discovery has conservation implications.

The Arapahoe snowfly was identified in 21 small streams along the Colorado Front Range between 1986 and 2017. As for almost all stoneflies, identification is based on subtle differences in appearance among species, but this can get confusing as even individuals of one species can look different based on age and sex. However, genetic identification is unaffected by the age, sex, or appearance of individuals, making this a more accurate tool for identifying species. By employing multiple molecular genetic techniques, scientists determined that the Arapahoe snowfly is a not distinct species.

“By understanding that the Arapahoe snowfly is not a distinct species, we can refocus our conservation priorities for other species and put our limited resources toward the greatest need,” said Matt Fairchild, co-author and fish biologist with the USDA Forest Service Arapaho and Roosevelt National Forests. “With the ingenuity of the National Genomics Lab, we put science to use on the Forest.”

In the new paper, Integrative taxonomy refutes a species hypothesis: The asymmetric hybrid origin of Arsapnia arapahoe (Plecoptera, Capniidae), the research team describe how they discovered that the Arapahoe snowfly is the result of unidirectional mating between males of one species and females of another species. Under the scientific rules for naming species, the Arapahoe snowfly can no longer be recognized as its own species.

“Genetic tools, like the ones we used for this project, can address a host of questions about rare species,” said Mike Young, lead author with the USDA Forest Service National Genomics Center for Wildlife and Fish Conservation. “This project is a perfect example of researchers providing the best available science to inform management actions.”

Related Publications

Young, Michael K. ; Smith, Rebecca J. ; Pilgrim, Kristine L. ; Fairchild, Matthew P. ; Schwartz, Michael K. , 2019

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Jennifer Hayes
Public and Legislative Affairs