JWM: What mammals are endemic to the Alexander Archipelago? 

Researchers are attempting to sort out the blurry understanding of which animals are endemic to the Alexander Archipelago in southeastern Alaska. 

Their results can help inform the management of the Tongass National Forest, which is currently conducting a management plan.  

“We’re hoping that this is a timely study for the revision of the Tongass Land and Resource Management Plan,” said Antonia Androski, the collections manager for mammals at Louisiana State University’s Museum of Natural Science.  

The Alexander Archipelago sits off the coast of southeastern Alaska. Most of the islands rest within the Tongass National Forest. Until recently, much of what scientists currently know about the taxonomy of mammals in the area hasn’t been updated since the early 1900s, when researchers surveyed and described the species. With over 1,000 named islands, this archipelago presents substantial ecological and evolutionary complexity. 

But Androski and her colleagues wanted to summarize new studies and update this information since Tongass National Forest was preparing a new mandated Land and Resource Management Plan, which includes a draft environmental impact statement. Various studies had been conducted on the genetics of different mammal species, but all the knowledge on genetic endemism in the Alexander Archipelago has not been assembled in over a decade. 

In a study published recently in the Journal of Wildlife Management, Androski, who was a PhD student at the University of New Mexico at the time, and her colleagues summarized the various studies on the genetic characteristics of mammal species in southeastern Alaska published since 2000.  

Genetic conundrum 

They discovered a mixed bag when it came to information and sample availability for the mammal species of southeastern Alaska. Some mammals formerly considered endemic to the archipelago weren’t that different from their mainland counterparts, while others that appeared the same as their mainland counterparts at a glance were genetically distinct. There also appeared to be signatures of past hybridization in some species.   

With regards to newly discovered endemic species, the Haida ermine (Mustela haidarum) was once believed to be a species but then dropped down to a subspecies of the Beringian ermine (M. erminea) in 1951. But more recent research found that the Haida ermine was indeed a species and found on several more islands in the Alexander Archipelago than scientists initially thought.  

Research also revealed that historic hybridization between Beringian ermines and the American ermine (M. richardsonii) “resulted in M. haidarum through hybrid speciation that was reinforced through island isolation,” Androski said.  

To date, the Haida ermine is the only mammal endemic to the region, the authors said, and it may be divided into two subspecies: the Suemez Island ermine (M. h. seclusa) found only on that island, and the Prince of Wales Island ermine (M. h. celenda) found on their namesake island and on four islands in the nearby Haida Gwaii Archipelago in British Columbia. 

Subspecies no more 

The researchers also summarized how some subspecies likely don’t quite qualify as subspecies—what was formerly considered the Revillagigedo Island red-backed vole (Clethrionomys gapperi solus) and the Wrangell Island red-backed vole (C. g. wrangeli), for example, which weren’t that different from other red-backed voles (C. gapperi) found across the continent.  

Another subspecies of vole, the long-tailed vole (Microtus longicaudus coronarius), was found on three islands rather than just the one that it was originally described from. 

Finally, the researchers concluded that limited sample availability means that there is not yet enough information to determine whether Alexander Archipelago wolves (Canis lupus ligoni), recently rejected for federal listing, were genetically distinct from mainland wolves, or whether they were similar to nearby mainland wolves but distinct from gray wolves (Canis lupus) elsewhere on the continent.   

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