The Northern Pike, Esox lucius,
is a large, carnivorous Fish found in freshwater ecosystems across the Northern
Hemisphere. Populations of Northern Pike are found across Europe, northern Asia
and northern North America, and are thought to have expanded across this range
from one or two refugia at the end of the last Ice Age, possibly crossing the
Bering Land Bridgebetween Siberia and Alaska. It is thought to be closely
related to the Amur Pike, Esox reichertii,
which is found only in the Amur River Basin in East Asia, which is separated
from the other river basins of Siberia (where the Northern Pike is found) by
the Yablonovy and Stanovoy mountain ranges. Three other species of Pike are
known from more southerly North American waterways, The American Pickerel, Esox americanus, the Muskellunge, Esox masquinongy and the Chain Pickerel Esox
niger, and two new species have recently been
described from Italy, the Southern Pikes, Esox cisalpinus and
Esox flaviae, though as these two
species were described separately they may turn out to be the same species.
Skog et al. determined
that the Amur Pike is genuinely a separate species to the Northern Pike the two
species having apparently separated about 4.55 million years ago. The Northern
Pike shows less genetic diversity across its entire range than the related Muskellunge,
though this has a much more limited range The Amur Pike has a similarly limited
genetic diversity.
The Northern Pike’s populations can be divided into three distinct
genetic lineages, which split about 200 000 to 300 000 years ago (i.e. during
the Late Pleistocene). All northern populations of Pike belong to a single one
of these populations, with the remaining two populations found at more
southerly latitudes within Europe only, one in Western Europe, the other in the
Danube Basin.
This strongly suggests that all northern populations of the Northern
Pike are descended from an ancestral population in a single refugia, that
spread around the Arctic Circle at or after the end of the Pleistocene. Within
this population, the highest genetic diversity is found in the Ural River
population, suggesting that all modern Northern Pike of the circumpolar
population may be descended from a Pleistocene population in this area, though
Skog et al. do not rule out a refugia
in West Siberia or even Beringia (the land between Alaska and Siberia that was
exposed by low sea levels during the Ice Ages, but which is covered by sea
now).
See also…
