On May 13, 1998 the U.S. Fish & Wildlife Service listed Preble's meadow jumping mouse (Zapus hudsonius preblei) as threatened under the Endangered Species Act. On Friday, January 28 the USFWS announced that “new research that indicates that the Preble’s meadow jumping mouse should not be classified as a separate subspecies of meadow jumping mouse.” The finding came in response to petitions for delisting filed by Wyoming's Governor and Coloradan's for Water Conservation and Development.
The first paragraph of the press release indicates that the Service “has begun the process to formally delist it,” but the fourth paragraph indicates that the Service “will analyze whether the Preble’s portion of Z. h. campestris qualifies as a Distinct Population Segment (DPS) in need of protection under the Endangered Species Act before this rule is finalized.”
In other words, the Service's official position is that it has not yet made a decision to delist Preble's meadow jumping mouse, which makes it all the more important to look at the evidence behind the decision.
The scientific findings (as yet unpublished) are found in a December 2004 report from the Denver Museum of Nature and Science.
Unfortunately, the authors appear to misinterpret their findings. They point out that AMOVA analyses of mtDNA sequence variation found that more than 30% of the genetic diversity was due to differences among the three subspecies included in the sample. When the two subspecies other than Preble's are considered, less than 4% of the difference resides among species. Thus, Preble's appears to be genetically distinct from the other two subspecies considered. Phylogenetic analyses place these three subspecies in the same clade, but humans and chimps are in the same clade too, and that doesn't mean they're the same thing. The authors contend that the AMOVA results “a lack
of strong genetic structure between these putative subspecies,” but a populaton geneticist finding that much differentiation among any other group of populations would regard that as substantial genetic differentiation.
Other evidence the authors present suggest that it may be reasonable to regard the three taxonomic subspecies as synonymous, but it nonetheless appears that Preble's meadow jumping mouse should be regarded as a distinct population segment for purposes of the Endangered Species Act and retain its status as threatened.
[UPDATE: I just noticed that the USFWS published a notice in Wednesday's Federal Register proposing to remove Preble's meadow jumping mouse from the list of Endangered and Threatened wildlife. Comments will come some time next week.]
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