Several years ago the Preble’s meadow jumping mouse, a threatened species that lives along the Rocky Mountain’s front range, skyrocketed to fame when a genetic study suggested that it may not actually qualify as a distinct subspecies and should therefore be removed from the Endangered Species Act. To their credit, the US Fish and Wildlife Service commissioned a second study to confirm the results, but the second study came to the dramatically different conclusion that the Preble’s mouse was indeed distinct. Again, to the credit of the Service, they assembled a scientific panel to weigh the two studies and found that the second study was superior in the amount and type of data that it used. Furthermore, the first study suffered from serious flaws including the fact that the authors had contaminated some of their samples. The Preble’s mouse was found to be distinct and its endangered species protections were left in place. Case Closed.
Fast forward to a new genetic study published in the December issue of Molecular Ecology that claims once again that the Preble’s meadow jumping mouse is “indistinct.” While the previous studies examined the relationships between Preble’s mice and other nearby subspecies in places like South Dakota and Nebraska, this study suggests that Preble’s mice are “part of a single lineage” that extends much further north and west in Canada and Alaska. The study also asserts that the Preble’s mice in Colorado are “ecologically interchangeable” with the mice in Canada and Alaska based on climate modeling.
Here’s what the study does do: the authors extended the geographic sampling of jumping mice and found that Preble’s mice are more closely related to subspecies to the far north rather than those that are physically closer to them to the east. The study also makes a number of proclamations that the Preble’s mouse is “indistinct” and that their “management” should be re-evaluated.
Here’s what the study doesn’t do: tell us whether the Preble’s meadow jumping mouse is (or isn’t) a valid subspecies. The type of genetic data that they used for this study simply cannot adequately address that question. Similarly, the data that they used to test for ecological exchangeability should include biological information (diet, behavior, growth rates, age at maturity, etc.) from the mice themselves. Instead, the study relies only on nonbiological factors like climate. This simply is not sufficient to conclude that the Preble’s mice and the habitat that they occupy are not unique.
Although the authors do concede that "additional tests" are necessary before concluding that the Preble's subspecies is invalid, this study is still likely to start a whole ‘nother push for the Preble’s meadow jumping mouse to be removed from the Endangered Species Act. Given the rigmarole that happened last time, the Service would be wise to wait for data that actually addresses the issue before heading down that twisted road again.
Image credit: USFWS