Researchers Reveal Archaeological History of Invasive Alaskan Species

The archaeological and genetic history of the Arctic ground squirrel, a species introduced to Chirikof Island, Alaska, is the subject of a new research study into the impact of invasive species to the region.

Researchers from the Smithsonian Conservation Biology Institute, Boston University, and the University of Oklahoma joined forces to study the mammal, which has the ability to impact life on Alaskan islands despite its small size. OU anthropology professor Courtney Hoffman and BU archaeology professor Courtney West studied Chirikof Island’s current squirrel population, discovering that the animals have been present there longer than previously thought, according to a recent press release.

While the spread of the Arctic ground squirrel is thought to be linked in part to the historic fox farming industry in the region, researchers found archaeological squirrel remains in middens; which they subjected to direct radiocarbon dating, examined evidence of prehistoric humans using these squirrels, and performed DNA analysis on these squirrel remains once dated.

The results of these three different lines of evidence revealed these ground squirrels have been present for at least 2,000 years on Chirikof Island. Additionally, the scientists determined through DNA study that the squirrels currently inhabiting the island are genetically similar to those who lived there in antiquity. These findings threaten to turn the long-held assumption that the species was brought to the islands as part of historic settlement.

West remarked that the Gulf of Alaska’s archaeological record readily provides researchers with a long-term look at interactions between humans and the environment, thanks to the presence of Native Americans in the region and their harvesting of resources over millennia. This age-old relationship can aid in understanding how complex contemporary interactions between humans and the environment can be, West added, stating that this could have repercussions for conservation efforts as well.

Many of the islands in the Gulf of Alaska are managed by the Alaska Maritime National Wildlife Refuge. This includes Chirikof Island, and the refuge now has to face how to make determinations as to whether species are native or invasive – and how to approach their populations in an appropriate manner. With the ground squirrel having been present on the island for several thousand years, this makes it a complex case when it comes to classifying it as truly invasive – and the new research study could change how the refuge approaches the handling of the local population and the restoration of the island.

Hoffman said that complex, important questions regarding the history of invasive species can be answered with more depth by using interdisciplinary methods such as zooarchaeology, radiocarbon dating, and ancient DNA analysis. This does, however, raise a question, the researcher remarked: how long must a species brought to a new environment live there for it to be considered a native part of the ecosystem, especially if it was introduced by ancient humans more than a thousand years in the past?

The new research study, published in the journal Conservation Biology, can be found online here

Image courtesy of University of Oklahoma

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