Coregonus

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.

Coregonus
Lake whitefish, Coregonus clupeaformis
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Salmoniformes
Family: Salmonidae
Subfamily: Coregoninae
Genus: Coregonus
Linnaeus, 1758
Type species
Coregonus lavaretus
Species

Nearly 70 extant members

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.

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.[2][3]

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.[3][4]

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.[5] It has been estimated that several of them are very young, having separated from each other less than 15,000 years ago.[6] 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).[7][8][9] 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.[7][8] Various Coregonus, whether regarded as separate species or not, readily interbreed with each other.[10] 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.[11]

Many European lakes have more than one Coregonus morph differing in ecology and morphology (especially gill rakers).[12] Such morphs are sometimes partially reproductively isolated from each other, leading to suggestions of recognizing them as separate but clinal species.[6] 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.[12] 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.[13][14][15][16]

Species

In 2017, FishBase listed 78 species, including the more than 50 proposed for Europe in 2007.[17] Some of these are recently extinct (marked with a dagger, "†") and C. reighardi is likely extinct.[5][15]

Cisco or lake herring, Coregonus artedi
Bloater, Coregonus hoyi
Common whitefish, Coregonus lavaretus (sensu lato)
Coregonus nelsonii
Coregonus pidschian

References
  1. Closs GP, Krkosek M, Olden JD, eds. (2016). Conservation of Freshwater Fishes. Cambridge University Press. p. 8. ISBN 978-1-107-04011-3.
  2. Whitelaw J (2015). Atlantic whitefish (Coregonus huntsmani) culture handbook. Dartmouth, Nova Scotia: Fisheries and Oceans Canada, Science Branch, Maritimes Region. ISBN 978-0-660-02539-1. OCLC 980875338.
  3. Crête-Lafrenière A, Weir LK, Bernatchez L (2012-10-05). "Framing the Salmonidae family phylogenetic portrait: a more complete picture from increased taxon sampling". PLOS ONE. 7 (10): e46662. Bibcode:2012PLoSO...746662C. doi:10.1371/journal.pone.0046662. PMC 3465342. PMID 23071608.
  4. Bernatchez L, Colombani F, Dodson JJ (December 1991). "Phylogenetic relationships among the subfamily Coregoninae as revealed by mitochondrial DNA restriction analysis" (PDF). Journal of Fish Biology. 39: 283–290. doi:10.1111/j.1095-8649.1991.tb05091.x.
  5. Kottelat M, Freyhof J (2007). Handbook of European Freshwater Fishes. Cornol, Switzerland: Publications Kottelat. ISBN 978-2-8399-0298-4.
  6. Hudson AG, Lundsgaard-Hansen B, Lucek K, Vonlanthen P, Seehausen O (March 2017). "Managing cryptic biodiversity: Fine-scale intralacustrine speciation along a benthic gradient in Alpine whitefish (Coregonus spp.)". Evolutionary Applications. 10 (3): 251–266. doi:10.1111/eva.12446. PMC 5322408. PMID 28250810.
  7. Østbye K, Bernatchez L, Naesje TF, Himberg KJ, Hindar K (December 2005). "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. doi:10.1111/j.1365-294X.2005.02737.x. PMID 16313599. S2CID 21487510.
  8. Jacobsen MW, Hansen MM, Orlando L, Bekkevold D, Bernatchez L, Willerslev E, Gilbert MT (June 2012). "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. doi:10.1111/j.1365-294X.2012.05561.x. PMID 22509795. S2CID 4499697.
  9. Ozerov MY, Himberg M, Aykanat T, Sendek DS, Hägerstrand H, Verliin A, et al. (May 2015). "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. doi:10.1111/jeb.12645. PMID 25877003. S2CID 13189069.
  10. "Maraena Whitefish (Coregonus maraena)" (PDF). U.S. Fish and Wildlife. 2017 [2011]. Retrieved 12 April 2018.
  11. Etheridge EC, Adams CE, Bean CW, Durie NC, Gowans AR, Harrod C, et al. (February 2012). "Are phenotypic traits useful for differentiating among a priori Coregonus taxa?". Journal of Fish Biology. 80 (2): 387–407. doi:10.1111/j.1095-8649.2011.03189.x. PMID 22268437.
  12. Bhat S, Amundsen PA, Knudsen R, Gjelland KØ, Fevolden SE, Bernatchez L, Præbel K (2014). "Speciation reversal in European whitefish (Coregonus lavaretus (L.)) caused by competitor invasion". PLOS ONE. 9 (3): e91208. Bibcode:2014PLoSO...991208B. doi:10.1371/journal.pone.0091208. PMC 3953381. PMID 24626131.
  13. Turgeon J, Estoup A, Bernatchez L (December 1999). "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. doi:10.1111/j.1558-5646.1999.tb04568.x. PMID 28565465. S2CID 12144534.
  14. Turgeon J, Bernatchez L (January 2003). "Reticulate evolution and phenotypic diversity in North American ciscoes, Coregonus ssp.(Teleostei: Salmonidae): implications for the conservation of an evolutionary legacy". Conservation Genetics. 4 (1): 67–81. doi:10.1023/A:1021860910719. S2CID 35532451.
  15. Eshenroder RL, Vecsei P, Gorman OT, Yule D, Pratt TC, Mandrak NE, et al. (Great Lakes Fishery Commission) (2016). Ciscoes (Coregonus, subgenus Leucichthys) of the Laurentian Great Lakes and Lake Nipigon (Report). United States Geological Survey.
  16. Boguski DA, Murray L, Pratt TC, Johnson JD, Reist JD (January 2014). Patterns of Morphological Diversity in Ciscoes Distributed Within Three of Manitoba's Glacial Relict Lakes with Reference to Shortjaw Cisco (Coregonus Zenithicus) (PDF). Canadian Science Advisory Secretariat = Secrétariat canadien de consultation scientifique (Report).
  17. Froese, Rainer and Pauly, Daniel, eds. (2017). Species of Coregonus in FishBase. December 2017 version.
  18. Selz OM, Dönz CJ, Vonlanthen P, Seehausen O (2020). "A taxonomic revision of the whitefish of lakes Brienz and Thun, Switzerland, with descriptions of four new species (Teleostei, Coregonidae)". ZooKeys (989): 79–162. doi:10.3897/zookeys.989.32822. PMC 7669820. PMID 33223897.
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