The American bullfrog is native to eastern North America, but now has a global distribution and is considered to be one of the worst invaders in the world. It is a relatively new invader in the Yellowstone River floodplain and was first documented in 1999.  USGS scientists at the Northern Rocky Mountain Science Center have been researching the bullfrog invasion within the Yellowstone River floodplain, as well as other locations in Montana and Wyoming.  Past research has documented the presence and extent of the bullfrog invasion, but this is the first study to use bullfrog genetics to track the path and history of the invasion in Montana.  Using genetic material from 395 tadpoles collected along the Yellowstone River, and additional sites in Montana and Wyoming, findings suggest at least four independent introductions into Montana from diverse sources. These data were compared to genetic data from bullfrogs sampled across their native range in eastern North America.  Three of seven genetic variants identified in Montana were identical to those previously found in native bullfrogs from the Midwest and Great Lakes regions. While genetic diversity was low in introduced bullfrogs, it did not differ significantly from potential source populations. The results also indicating that the spread of bullfrogs in the Yellowstone has likely occurred via natural dispersal following introduction. Evidence for multiple invasions of bullfrogs and lack of subsequent regional spread emphasizes the importance public education and legislation that prohibit bullfrogs from being imported into non-native ranges such as Montana.  

The study is entitled, “Genetic reconstruction of a bullfrog invasion to elucidate vectors of introduction and secondary spread" and is published in the journal Ecology and Evolution. It can be found at this website.  

Back to NOROCK