A circumpolar distribution is any range of a taxon that occurs over a wide range of longitudes but only at high latitudes; such a range therefore extends all the way around either the North Pole or the South Pole. [1] [2] Taxa that are also found in isolated high-mountain environments further from the poles are said to have arctic–alpine distributions. [3]
In biology, a taxon is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and given a particular ranking, especially if and when it is accepted or becomes established. It is not uncommon, however, for taxonomists to remain at odds over what belongs to a taxon and the criteria used for inclusion. If a taxon is given a formal scientific name, its use is then governed by one of the nomenclature codes specifying which scientific name is correct for a particular grouping.
Longitude, is a geographic coordinate that specifies the east–west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians connect points with the same longitude. By convention, one of these, the Prime Meridian, which passes through the Royal Observatory, Greenwich, England, was allocated the position of 0° longitude. The longitude of other places is measured as the angle east or west from the Prime Meridian, ranging from 0° at the Prime Meridian to +180° eastward and −180° westward. Specifically, it is the angle between a plane through the Prime Meridian and a plane through both poles and the location in question.
Animals with circumpolar distributions include the reindeer, [1] [2] polar bear, [4] Arctic fox, [1] [5] snowy owl, [5] snow bunting, [5] king eider, [5] brent goose [5] and long-tailed skua [5] in the north, and the Weddell seal [1] and Adélie penguin [1] in the south.
The reindeer, also known as the caribou in North America, is a species of deer with circumpolar distribution, native to Arctic, sub-Arctic, tundra, boreal, and mountainous regions of northern Europe, Siberia, and North America. This includes both sedentary and migratory populations. Rangifer herd size varies greatly in different geographic regions. The Taimyr herd of migrating Siberian tundra reindeer in Russia is the largest wild reindeer herd in the world, varying between 400,000 and 1,000,000. What was once the second largest herd is the migratory boreal woodland caribou George River herd in Canada, with former variations between 28,000 and 385,000. As of January 2018, there are fewer than 9,000 animals estimated to be left in the George River herd, as reported by the Canadian Broadcasting Corporation. The New York Times reported in April 2018 of the disappearance of the only herd of southern mountain caribou in the lower 48 states, with an expert calling it "functionally extinct" after the herd's size dwindled to a mere three animals.
The polar bear is a hypercarnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is a large bear, approximately the same size as the omnivorous Kodiak bear. A boar weighs around 350–700 kg (772–1,543 lb), while a sow is about half that size. Although it is the sister species of the brown bear, it has evolved to occupy a narrower ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice and open water, and for hunting seals, which make up most of its diet. Although most polar bears are born on land, they spend most of their time on the sea ice. Their scientific name means "maritime bear" and derives from this fact. Polar bears hunt their preferred food of seals from the edge of sea ice, often living off fat reserves when no sea ice is present. Because of their dependence on the sea ice, polar bears are classified as marine mammals.
The Arctic fox, also known as the white fox, polar fox, or snow fox, is a small fox native to the Arctic regions of the Northern Hemisphere and common throughout the Arctic tundra biome. It is well adapted to living in cold environments, and is best known for its thick, warm fur that is also used as camouflage. On average, Arctic foxes only live 3–4 years in the wild. Its body length ranges from 46 to 68 cm, with a generally rounded body shape to minimize the escape of body heat.
Plants with northern circumpolar distributions include Eutrema edwardsii (syn. Draba laevigata), [2] Saxifraga oppositifolia , [3] Persicaria vivipara [6] and Honckenya peploides . [7] [8] [9]
Saxifraga oppositifolia, the purple saxifrage or purple mountain saxifrage, is a species of edible plant that is very common all over the high Arctic and also some high mountainous areas further south, including northern Britain, the Alps and the Rocky Mountains. It is even known to grow on Kaffeklubben Island in north Greenland, at 83°N40°E, the most northerly plant locality in the world.
