Coregonus Explained

Coregonus is a diverse genus of fish in the salmon family (Salmonidae). The Coregonus species are known as whitefishes. The genus contains at least 68 described extant taxa, but the true number of species is a matter of debate. The type species of the genus is Coregonus lavaretus.

Most Coregonus species inhabit lakes and rivers, and several species, including the Arctic cisco (C. autumnalis), the Bering cisco (C. laurettae), and the least cisco (C. sardinella) are anadromous, moving between salt water and fresh water.

Many whitefish species or ecotypes, especially from the Great Lakes and the Alpine lakes of Europe, have gone extinct over the past century or are endangered. Among 12 freshwater fish considered extinct in Europe, 6 are Coregonus.[1] All Coregonus species are protected under appendix III of the Bern Convention,[2] and Annex IV of the EC Habitats Directive (92/43/EEC)[3]

Taxonomy

Phylogenetic evidence indicates that the most basal member of the genus is the highly endangered Atlantic whitefish (C. huntsmani), which is endemic to a single river basin in Nova Scotia, Canada. The Atlantic whitefish is thought to have diverged from the rest of the genus during the mid-Miocene, about 15 million years ago.[4] [5]

The genus was previously subdivided into two subgenera Coregonus ("true whitefishes") and Leucichthys ("ciscoes"), Coregonus comprising taxa with sub-terminal mouth and usually a benthic feeding habit, Leucichthys those with terminal or supra-terminal mouth and usually a pelagic plankton-feeding habit. This classification is not natural however: based on molecular data, ciscoes comprise two distinct lineages within the genus. Moreover, the genus Stenodus is not phylogenetically distinct from Coregonus; although Stenodus occupies a basal position within the genus, phylogenetic evidence indicates that C. huntsmani is even more basal than it.[6]

The scientific name given to this genus of fish comes from the Greek κόρη (kórē) "daughter ; eye pupil" and γωνία (gōnía) "angle",[7] because their pupil makes an angle, even though they share this feature with a large number of other fish.

Species diversity

There is much uncertainty and confusion in the classification of the many of species of this genus. Particularly, one extreme view of diversity recognises just two main species in Northern and Central Europe, the common whitefish C. lavaretus and the vendace C. albula, whereas others would divide these into numerous, often narrowly distributed species. A drastic increase in number of recognized species occurred in 2007, when a review advocated that more than 50 local European populations should be considered as distinct based on morphological differences.[8] It has been estimated that several of them are very young, having separated from each other less than 15,000 years ago.[9] Many of these were primarily defined based on number of gill rakers. Although this largely is hereditary, the number is highly variable (even within single populations and species), can change relatively fast in response to changes and genetic studies have shown that they often are of limited use in predicting relationships among populations (a large difference in gill raker number does not necessarily equal a distant relationship).[10] [11] [12] Genetic differences between several of the recently proposed species, even ones that are relatively distinct morphologically, are very limited and sometimes they are not monophyletic. Various Coregonus, whether regarded as separate species or not, readily interbreed with each other.[13] A review of whitefish in the United Kingdom found that the identification key provided in 2007 did not match most individuals and that solid evidence for more than one species in that region is lacking.[14]

Many European lakes have more than one Coregonus morph differing in ecology and morphology (especially gill rakers).[15] Such morphs are sometimes partially reproductively isolated from each other, leading to suggestions of recognizing them as separate but clinal species. The morphs or clinal species may rapidly disappear (in 15 years or less, equalling three Coregonus generations) by merging into a single in response to changes in the habitat. A similar pattern can be seen in North America where the ciscoes of the Coregonus artedi complex in the Great Lakes and elsewhere comprise several, often co-occurring morphs or ecotypes, whose taxonomic status remains controversial.[16] [17] [18] [19]

Species

In 2017, FishBase listed 78 species, including the more than 50 proposed for Europe in 2007. Some of these are recently extinct (marked with a dagger, "†") and C. reighardi is likely extinct.

External links

Notes and References

  1. Book: Closs GP, Krkosek M, Olden JD . 2016 . Conservation of Freshwater Fishes . 8 . Cambridge University Press . 978-1-107-04011-3 .
  2. Council of Europe, 1979. Convention on the Conservation of European Wildlife and Natural Heritage. Bern, Switzerland. Available at: http://conventions.coe.int/Treaty/EN/Treaties/Html/104.htm
  3. Web site: Council Directive 92/43/EEC of 21 May 1992 . Eur-lex.europa.eu . 2010-03-15.
  4. Book: Whitelaw J . 2015 . Atlantic whitefish (Coregonus huntsmani) culture handbook . Fisheries and Oceans Canada, Science Branch, Maritimes Region . Dartmouth, Nova Scotia . 978-0-660-02539-1 . 980875338.
  5. Crête-Lafrenière A, Weir LK, Bernatchez L . Framing the Salmonidae family phylogenetic portrait: a more complete picture from increased taxon sampling . PLOS ONE . 7 . 10 . e46662 . 2012-10-05 . 23071608 . 3465342 . 10.1371/journal.pone.0046662 . 2012PLoSO...746662C . free .
  6. Bernatchez L, Colombani F, Dodson JJ . Phylogenetic relationships among the subfamily Coregoninae as revealed by mitochondrial DNA restriction analysis. . Journal of Fish Biology . December 1991 . 39 . 283–290 . 10.1111/j.1095-8649.1991.tb05091.x .
  7. Web site: Coregonus nilssoni Valenciennes, 1848 . . FishBase . 17 August 2024 .
  8. Book: Kottelat M, Freyhof J . Handbook of European Freshwater Fishes . 2007 . Publications Kottelat . Cornol, Switzerland . 978-2-8399-0298-4.
  9. Hudson AG, Lundsgaard-Hansen B, Lucek K, Vonlanthen P, Seehausen O . Managing cryptic biodiversity: Fine-scale intralacustrine speciation along a benthic gradient in Alpine whitefish (Coregonus spp.) . Evolutionary Applications . 10 . 3 . 251–266 . March 2017 . 28250810 . 5322408 . 10.1111/eva.12446 .
  10. Østbye K, Bernatchez L, Naesje TF, Himberg KJ, Hindar K . Evolutionary history of the European whitefish Coregonus lavaretus (L.) species complex as inferred from mtDNA phylogeography and gill-raker numbers . Molecular Ecology . 14 . 14 . 4371–4387 . December 2005 . 16313599 . 10.1111/j.1365-294X.2005.02737.x . 21487510 .
  11. Jacobsen MW, Hansen MM, Orlando L, Bekkevold D, Bernatchez L, Willerslev E, Gilbert MT . Mitogenome sequencing reveals shallow evolutionary histories and recent divergence time between morphologically and ecologically distinct European whitefish (Coregonus spp.) . Molecular Ecology . 21 . 11 . 2727–2742 . June 2012 . 22509795 . 10.1111/j.1365-294X.2012.05561.x . 4499697 .
  12. Ozerov MY, Himberg M, Aykanat T, Sendek DS, Hägerstrand H, Verliin A, Krause T, Olsson J, Primmer CR, Vasemägi A . 6 . Generation of a neutral FST baseline for testing local adaptation on gill raker number within and between European whitefish ecotypes in the Baltic Sea basin . Journal of Evolutionary Biology . 28 . 5 . 1170–1183 . May 2015 . 25877003 . 10.1111/jeb.12645 . 13189069 . free .
  13. Web site: U.S. Fish and Wildlife . 2011 . 2017 . Maraena Whitefish (Coregonus maraena). . 12 April 2018 .
  14. Etheridge EC, Adams CE, Bean CW, Durie NC, Gowans AR, Harrod C, Lyle AA, Maitland PS, Winfield IJ . 6 . Are phenotypic traits useful for differentiating among a priori Coregonus taxa? . Journal of Fish Biology . 80 . 2 . 387–407 . February 2012 . 22268437 . 10.1111/j.1095-8649.2011.03189.x . free .
  15. Bhat S, Amundsen PA, Knudsen R, Gjelland KØ, Fevolden SE, Bernatchez L, Præbel K . Speciation reversal in European whitefish (Coregonus lavaretus (L.)) caused by competitor invasion . PLOS ONE . 9 . 3 . e91208 . 2014 . 24626131 . 3953381 . 10.1371/journal.pone.0091208 . 2014PLoSO...991208B . free .
  16. Turgeon J, Estoup A, Bernatchez L . Species Flock in the North American Great Lakes: Molecular Ecology of Lake Nipigon Ciscoes (Teleostei: Coregonidae: Coregonus). . Evolution; International Journal of Organic Evolution . 53 . 6 . 1857–1871 . December 1999 . 28565465 . 10.1111/j.1558-5646.1999.tb04568.x . 12144534 . free .
  17. Turgeon J, Bernatchez L . Reticulate evolution and phenotypic diversity in North American ciscoes, Coregonus ssp.(Teleostei: Salmonidae): implications for the conservation of an evolutionary legacy. . Conservation Genetics . January 2003 . 4 . 1 . 67–81 . 10.1023/A:1021860910719 . 35532451 .
  18. Eshenroder RL, Vecsei P, Gorman OT, Yule D, Pratt TC, Mandrak NE, Bunnell DB, Muir AM . 6 . Ciscoes (Coregonus, subgenus Leucichthys) of the Laurentian Great Lakes and Lake Nipigon. . Great Lakes Fishery Commission . United States Geological Survey . 2016 .
  19. Boguski DA, Murray L, Pratt TC, Johnson JD, Reist JD . Patterns of Morphological Diversity in Ciscoes Distributed Within Three of Manitoba's Glacial Relict Lakes with Reference to Shortjaw Cisco (Coregonus Zenithicus) . Canadian Science Advisory Secretariat = Secrétariat canadien de consultation scientifique . January 2014 .
  20. Selz OM, Dönz CJ, Vonlanthen P, Seehausen O . A taxonomic revision of the whitefish of lakes Brienz and Thun, Switzerland, with descriptions of four new species (Teleostei, Coregonidae) . ZooKeys . 989 . 79–162 . 2020 . 33223897 . 7669820 . 10.3897/zookeys.989.32822 . free .

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