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© 2011 Museum of Southwestern Biology. All rights reserved.

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What is an Endemic?
An endemic is a distinct, unique organism found within a restricted area or range. A restricted range may be an island, or a group of islands, and in the case of some endemic mammals within the Alexander Archipelago, a restricted region such as the North Pacific Coast. The term “endemism” holds special importance on island systems, because many organisms are restricted in distribution to a single island or groups of islands. For example, of the known bird species throughout the world, 20% are considered “island endemics” because they are found only within island systems. The North Pacific Coast is a hot spot for endemism because of its historical isolation, ecological complexity, and narrow distribution between the Pacific Ocean and coastal mountain ranges. Within Southeast Alaska, almost 20% of known mammal taxa (species and subspecies) have been described as endemic to the region (see list to right). The long-term viability of these endemic populations is unknown, but of increasing concern. Island endemics are extremely susceptible to extinction because of restricted ranges, specific habitat requirements, and sensitivity to human activities such as species introductions. They usually experience high rates of inbreeding resulting from small population sizes and therefore suffer from the consequences of reduced genetic variation. Finally, the land masses of islands are smaller than those of nearby continents, and are more susceptible to random climatic events (such as storms) or massive habitat disruption. More than 81% of mammalian extinctions in the last 500 years have been insular endemic mammals. Islands, which tend to harbor extremely high biodiversity concentrated in a relatively small area, may be major driving forces in diversification and ultimately speciation. Therefore, archipelagos such as the Alexander Archipelago of Southeast Alaska are essential to maintaining and increasing global biodiversity. It is impossible to measure the current susceptibility of endemics within the Alexander Archipelago because little information is known about their occurrence, distribution, population sizes, and vulnerabilities. Current research on endemics throughout the Alexander Archipelago is primarily focused on mammals, but should include other organisms. The number of endemic plants, birds, amphibians, and invertebrates are not known for this archipelago. Because mammals often have the lowest percentage of endemics within an island system, other organisms may show much higher levels of endemism within the Alexander Archipelago. (41 KB PDF of a working document on the endemic animals and plants of Southeast Alaska and adjacent British Columbia here.)

Endemism in Southeast Alaska
Early explorers and naturalists identified the Alexander Archipelago as a distinctive geographic region, the “Sitkan District.” Distinctive organisms were described on several islands in the archipelago even though fewer than 25 islands were visited. Some endemics were described from only one specimen found on one island (for example, Suemez Island ermine Mustela erminea seclusa), while others were described from multiple islands (M. erminea celenda on Prince of Wales, Dall, and Long islands). Altogether, 24 of 107 mammal taxa were recognized as endemic based on morphological characteristics (MacDonald and Cook 1996). Recent technological advances provide independent perspectives on these endemics based on molecular genetic characters. Many of these new techniques provide a more rigorous assessment of levels of divergence among island endemics and mainland populations than the early surveys described above. These new approaches successfully evaluated the status of endemics on archipelagos elsewhere across the globe and now are being applied to endemics within the Alexander Archipelago. Molecular studies have uncovered hidden diversity and are providing new insight into the status of island populations as endemics. Eight endemic mammalian lineages have been identified within the Alexander Archipelago. More mammals and a suite of other organisms need to be examined to paint a more accurate picture of endemism within this archipelago.

                                    ... from Dawson et al. 2007 (PDF 1.47MB)



Threats to Endemism
One of the main facets of maintaining biodiversity is the ability to recognize and conserve unique endemic organisms. Endemic types or species are especially likely to develop on islands because of their geographical isolation. Island endemics, in particular, can easily become endangered or extinct because of their restricted habitat and vulnerability to the actions of man, including the introduction of exotic organisms and associated pathogens, over-exploitation, and secondary ripple effects.
Endemic Mammal Taxa
of Southeast Alaska

RODENTS
Beaver
  Castor canadensis phaeus

Northern Flying Squirrel
  Glaucomys sabrinus griseifrons

Hoary Marmot
  Marmota caligata vigilis

Long-tailed Vole
  Microtus longicaudus coronarius

Root Vole
  Microtus oeconomus sitkensis
  M. o. yakutatensis

Meadow Vole
  Microtus pennsylvanicus admiraltiae

Southern Red-backed Vole
  Myodes gapperi solus
  M. g. stikinensis
  M. g. wrangeli

Northern Red-backed Vole
  Myodes rutilus glacialis

Northwestern Deermouse
  Peromyscus keeni hylaeus
  P. k. oceanicus
  P. k. sitkensis

Red Squirrel
  Tamiasciurus hudsonicus picatus

SHREWS
Glacier Bay Water Shrew
  Sorex alaskanus

Cinereus Shrew
  Sorex cinereus streatori

Dusky Shrew
  Sorex monticolus elassodon
  S. m. malitiosus

CARNIVORES
Wolf
  Canis lupus ligoni

River Otter
  Lontra canadensis mira

Pacific Marten
  Martes caurina

Ermine
  Mustela erminea alascensis
  M. e. celenda
  M. e. initis
  M. e. salva
  M. e. seclusa
  M. (e.) haidarum (incl. celenda,
         seclusa)

Black Bear
  Ursus americanus emmonsii
  U. a. pugnax

Brown Bear
  Ursus arctos dalli
  U. a. sitkensis

ENDEMISM HOTSPOTS of the Alexander Archipelago map ...

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Conservation Status of Southeast Alaska Small Mammals (PDF 24 KB)...

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Exotics working table (PDF 82 KB)...

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Parasites and Pathogens working table (PDF 20 KB)...

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