Refuge Notebook: Genetic diversity of wildlife on the Kenai Peninsula is a mixed bag

There are 1,786 plant and animal species known on the Kenai National Wildlife Refuge. That’s extraordinary biodiversity for this latitude with perhaps another 3,000 species, by my estimation, yet to be found. George Shiras III, a famous National Geographic Society photographer, wasn’t kidding when he wrote that “were all of Alaska erased from the map except the Kenai Peninsula and its immediately adjacent waters, there would yet remain in duplicate that which constitutes the more unique and that which typifies the whole of this wonderful country.”

What makes the Kenai Peninsula so species rich is the intersection of the Sitka-spruce rainforest that colonized Prince William Sound with the drier white and black spruce boreal forest that extends from interior Alaska to the Cook Inlet. Combined with elevations ranging from sea level to 6,000 feet in the Harding Icefield, Mother Nature has created lots of ecological niches to be filled by species.

But because we live on a peninsula that is separated from the adjacent mainland by a narrow, 10-mile wide isthmus only recently de-glaciated, it’s logical to assume that plant dispersal and wildlife movement have been minimal with restricted genetic mixing. So although species diversity is relatively high, we would expect low genetic diversity within populations of most species on the Kenai Peninsula.

On the other hand, a paper published in Science in 2003 showed that the diversity of chloroplast DNA in European plant species was highest in areas where populations dispersing from northern and southern refugia collided in the aftermath of the last ice age. Such a place could be the Kenai Peninsula, an area in which at least some species may have been colonized by populations originating from both northern (Beringia) and southern refugia.

In fact, Caribou Hills, nunataks in the Harding Ice Field, and the northern part of the Kenai Mountains around Big Indian Creek were unglaciated during the last ice age, serving as local refugia for some flora and fauna. So genetic diversity might be low because it’s an isolated peninsula or it might be high because of post-Pleistocene colonization patterns.

It only gets more confusing because there are different ways of measuring genetic diversity. Modern genetics considers variation in nuclear DNA versus mitochondrial DNA. Unlike nuclear DNA, which is inherited from both parents and in which genes are rearranged in the process of recombination, there is usually no change in mitochondrial DNA from parent (usually the mother) to offspring. As such, mitochondrial DNA is a powerful tool for tracking ancestry through females.

Consider Kenai brown bears. A study published in the Canadian Journal of Zoology shows they have lower levels of mitochondrial DNA diversity than most other brown bear populations in Alaska, including the Kodiak Archipelago, but relatively high nuclear diversity. The former could result from a few reproductive sows that are highly successfully. Conversely, the latter could be due to high gene flow from males that disperse widely coupled with a tendency of females to stay close to home. As the authors suggested, determining which mechanism is in play is important for effective management of the Kenai brown bear population — there’s a danger of harvesting the wrong sows or too many boars.

In contrast, Kenai moose were found to have higher genetic diversity than populations elsewhere in North America and Scandinavia. Kris Hundertmark, originally at the Kenai Moose Research Center when this study was published in 1992, and his colleagues found that genetic diversity, as measured by polymorphic loci in liver and muscle samples from moose killed by collisions with vehicles, was unusually high. They suggested that this was so because the Kenai population likely originated from moose that survived the last ice age in nearby climate refugia (Beringia).

Wolverines from the Kenai Peninsula were similarly found to harbor a disproportionate amount of the mitochondrial diversity in North American populations. Furthermore, the Kenai population was considered somewhat distinctive, with a single unique haplotype. While the authors of this study, published in the Journal of Mammology, suggested that the genetic structure of our wolverine is not enough to warrant designation as a subspecies (recognized as Gulo gulo katschemakensis in 1918), they also acknowledged that our local population deserves special conservation attention.

Similarly, Trumpeter swans on the Kenai Peninsula were found to have slightly higher genetic diversity based on nuclear DNA than other populations in the western U.S. However, the authors of this study, from the University of Denver and U.S. Geological Survey, concluded that the diversity was not enough to warrant special management consideration.

At the end of the day, why should we care about genetic diversity? Genetic diversity plays an important role in the survival and adaptability of a species to environmental stressors such as rapid climate change, disease or contaminants, or how successful a native species might be in responding to competition from invasive exotic species. Variation in a population’s gene pool provides variable traits among the individuals of that population. Like making the wise decision to not put all your eggs in one basket, having multiple baskets of varying sizes ensures that someone gets home with at least some of the eggs. More genetic diversity means greater resilience in a population or species to survive environmental change, exactly what is needed to sustain our diverse biota on the Kenai Peninsula.

John Morton is the supervisory biologist at Kenai National Wildlife Refuge. You can find more information about the refuge at http://kenai.fws.gov or http://www.facebook.com/kenainationalwildliferefuge.

More in Life

Minister’s Message: Who is this man?

Over and over again, they struggle to rightly name who he is and what he’s up to

A still from “Casting Maya,” a film about Ascension Bay on the Yucatan Peninsula in Mexico is seen in this screenshot. From Pure Films, the short will be one of nine shown at the International Fly Fishing Film Festival on Aug. 10 in Kenai, Alaska. (IF4/flyfilmfest.com)
Anglers’ night out

Annual International Fly Fishing Film Festival returns to Kenai

Candy pecans make a sweet snack to enjoy on excursions. (Photo by Tressa Dale/Peninsula Clarion)
Road trip reimagined

Candied pecans accompany more subdued wandering

Robert C. Lewis photo courtesy of the Alaska Digital Archives 
Ready to go fishing, a pair of guests pose in front of the Russian River Rendezvous in the early 1940s.
The Disappearing Lodge, Part 1

By the spring of 1931, a new two-story log building — the lodge’s third iteration — stood on the old site, ready for business

Viola Davis stars in “The Woman King.” (Sony Pictures Entertainment Inc.)
On the screen: Women reign in latest action flick

‘The Woman King’ is a standout that breaks new ground

Artwork donated for the Harvest Auction hangs at the Kenai Art Center on Tuesday, Aug. 30, 2022, in Kenai, Alaska. (Jake Dye/Peninsula Clarion)
Auction, juried show to showcase local talent

Kenai Art Center will host its annual Harvest Auction this weekend, juried art show next month

Sweet and tart cranberry pecan oat bars are photographed. (Photo by Tressa Dale/Peninsula Clarion)
Cranberries to match the bright colors of fall

Delicious cranberry pecan oat bars are sweet and tart

Will Morrow (courtesy)
Take a chance

The fact of the matter is, you can find a way to hurt yourself in just about any athletic endeavor.

Alaska Digital Archives
George W. Palmer (left), the namesake for the city in the Matanuska Valley and the creek near Hope, poses here with his family in 1898 in the Knik area. Palmer became a business partner of Bill Dawson in Kenai in the last years of Dawson’s life.
Bill Dawson: The Price of Success, Part 5

Thus ended the sometimes tumultuous Alaska tenure of William N. Dawson.

Minister’s Message: Plenty

The Bible story of Joseph in Egypt preparing the harvest in the seven years of plenty teaches us some vital lessons

A still from “Jazzfest.” (Photo provided)
DocFest could be the golden year of documentaries — again

Homer Documentary Film Festival returns for 18th year with solid mix

From left: Lacey Jane Brewster, Terri Zopf-Schoessler, Donna Shirnberg, Tracie Sanborn and Bill Taylor (center) rehearse “Menopause Made Me Do It” on Tuesday, Sept. 13, 2022, in Soldotna, Alaska. (Jake Dye/Peninsula Clarion)
Applause for menopause

Kenai Performers’ new play takes aim at ‘not the most glorious part of womanhood’