Saturday, 27 September 2014

The genetic diversity of the Northern Pike and itrs relationship with the Amur Pike.

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.

The Northern Pike, Esox lucius. Animal Base.

In a paper published in the journal Frontiers in Zoology on 16 September 2014, Anna Skog of the Centre for Ecological and EvolutionarySynthesis at the Department of Biosciences at the University of Oslo and the CancerRegistry of Norway, Asbjørn Vøllestad and Nils Stenseth, also of the Centre for Ecological and Evolutionary Synthesis, Alexander Kasumyan of the Department ofIchthyology at the Faculty of Biology at Moscow State University and Kjetill Jakobsen, also of the Centre for Ecological and Evolutionary Synthesis describe the results of  genetic study of 24 populations of Northern Pike and three populations of Amur Pike, intended to determine the relationships between the two 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 Amur Pike, Esox reichertii. Pikefinder.

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… African Tigerfish observed snatching Barn Swallows from the air.                                      A variety of Fish are known to occasionally take Birds as prey. Sharks...

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