Stocks are Chameleons: Plasticity in Gill Rakers of Coregonid Fishes

1981 ◽  
Vol 38 (12) ◽  
pp. 1497-1506 ◽  
Author(s):  
C. C. Lindsey
Keyword(s):  
Gene Flow ◽  
Northern Hemisphere ◽  
Phenotypic Variation ◽  
Morphological Characters ◽  
Yukon Territory ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Gill Rakers ◽  
Gill Raker ◽  
Coregonid Fishes

The characters that apparently render a stock of fish distinctive may in reality be a reflection of the presence or absence of other fish species with which the stock shares its environment. Over the northern hemisphere, the whitefish genera Coregonus, "Leucichthys," and Prosopium offer striking examples of morphological characters being displaced because of coinhabiting species. Whenever one of the groups is missing, another tends to shift its gill rakers so as to fill in the vacant part of the spectrum in gill-raker counts. Plankton-feeding lake whitefish (Coregonus clupeaformis) having many long gill rakers exist in several lakes sympatrically with bottom-feeding lake whitefish having fewer and shorter gill rakers, but only if the even more specialized plankton-feeding species of ciscoes are absent. Lake whitefish in Yukon Territory have on the average fewer rakers in those lakes that contain ciscoes than in those that do not. Artificial transplants demonstrate that gill-raker characteristics can change quickly in a new environment. Gill-raker count is less subject to phenotypically induced variation from environmental influences than are most morphological characters, but it is not immune. Partial hybridization, where bimodal populations are maintained by a balance between gene flow and selection, also poses special problems for the stock concept. When employing even relatively stable characters such as gill-raker counts, one should beware that the "stocks" may be chameleons which shift their appearance in response to the biological color of their surroundings.Key words: coregonids, whitefish, gill rakers, phenotypic variation, hybridization, selection, transplants, stocks

Morphological and Ecological Divergence Within the Lake Whitefish (Coregonus clupeaformis) Species Complex in Yukon Territory

1979 ◽  
Vol 36 (10) ◽  
pp. 1214-1222 ◽  
Author(s):  
R. A. Bodaly
Keyword(s):  
Lake Water ◽  
Species Complex ◽  
Yukon Territory ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Sympatric Populations ◽  
Gill Rakers ◽  
Growth Divergence ◽  
Gill Raker ◽  
Plankton Feeders

Two forms of lake whitefish (Coregonus clupeaformis species complex sensu McPhail and Lindsey [1970]) were found in each of five lakes in Yukon Territory. They are characterized by differences in gill raker counts. Low gill raker fish are benthic feeders and are found almost exclusively near the bottom while high raker fish are largely plankton feeders, being found throughout the lake water column. High raker fish have longer and more closely spaced gill rakers than low raker fish. They also have shorter life spans and mature earlier than low raker fish. Lakes supporting these sympatric populations of lake whitefish have no cisco populations. The low gill raker member of these sympatric populations seems to be equivalent to most other Yukon lake whitefish whereas the high raker member appears to be the unusual member of each sympatric pair. Key words: whitefish, lake, feeding, morphology, growth, divergence, Yukon Territory, sympatric populations

Phenotypic Variation in the Lake Whitefish, Coregonus clupeaformis, Induced by Introduction into a New Environment

1974 ◽  
Vol 31 (1) ◽  
pp. 55-62 ◽  
Author(s):  
J. S. Loch
Keyword(s):  
Feeding Habits ◽  
Morphological Characters ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Meristic Characters ◽  
Line Scale ◽  
Benthic Food ◽  
Glycerol 3 Phosphate Dehydrogenase ◽  
Gill Raker ◽  
Electrophoretic Phenotype

Adult lake whitefish (Coregonus clupeaformis) from Clearwater Lake and second generation adults of offspring from Clearwater whitefish transplanted to Lyons Lake were compared with respect to morphometric and meristic characters and isozymes of L-glycerol-3-phosphate dehydrogenase (GPDH). Feeding habits and abundance of pelagic and benthic foods were compared in the two lakes.Gill raker number, lateral line scale count, and interorbital width remained constant between parental and offspring populations. Gill raker length was the main character found to differ between the populations. This was found to be related to the percentage and type of benthic food eaten. Abrasion of the gill rakers is offered as an explanation for the differences in gill raker length. Differences were found in various other meristic and morphological characters, as well as in electrophoretic phenotype frequencies of isozymes of GPDH.

Sympatric Occurrence of Two Species of Humpback Whitefish in Squanga Lake, Yukon Territory

1963 ◽  
Vol 20 (3) ◽  
pp. 749-767 ◽  
Author(s):  
C. C. Lindsey
Keyword(s):  
Gonad Development ◽  
Morphological Characters ◽  
Yukon Territory ◽  
The Other ◽  
Coregonus Clupeaformis ◽  
Early Winter ◽  
High Count ◽  
Morphometric Characters ◽  
Yukon River ◽  
Gill Raker

Squanga Lake in the Canadian headwaters of the Yukon River contains two species of humpback whitefish, characterized by modal first arch gill raker counts of 23 and 28 but with overlap in the range of counts. The species can be separated more sharply by raker counts of the second arch, also with modes of 23 and 28. Seven other morphometric characters not correlated with gill raker count each have significantly different means, but some overlap, between the species.In June the species with high raker count mainly occupies the pelagic zone, while the low count species occupies the bottom layers at all depths. The high count species feeds mainly on plankton, the low count species on bottom organisms. The high count species spawns in inlet and outlet streams in November and December. Gonad development in June suggests that the low count form spawns later, in localities unknown. Samples from early winter spawning runs contained exclusively high count individuals. A few fish, probably hybrids, had raker count corresponding to one species and most other morphological characters corresponding to the other. Tentative names for the species are Coregonus clupeaformis (high gill raker count) and Coregonus pidschian.

Lack of specialization in trophic morphology between genetically differentiated dwarf and normal forms of lake whitefish (Coregonus clupeaformis Mitchill) in Lac de l'Est, Quebec

1996 ◽  
Vol 74 (11) ◽  
pp. 1989-1998 ◽  
Author(s):  
Angelo Chouinard ◽  
Dany Pigeon ◽  
Louis Bernatchez
Keyword(s):  
Gene Flow ◽  
Trophic Ecology ◽  
Early Stage ◽  
Population Divergence ◽  
Gene Pools ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Apparent Lack ◽  
Enzyme Loci ◽  
Trophic Niches

We recently observed a bimodal distribution in size of sexually maturing lake whitefish (Coregonus clupeaformis Mitchill) in Lac de L'Est, Quebec. The objective of this study was to test the hypothesis that these two spawning size classes represent genetically distinct ecotypes, potentially adapted in morphology for occupying different trophic niches. This was accomplished by quantifying the extent of genetic (mitochondrial DNA (mtDNA) and enzyme loci) and morphological differences. Significant differences in haplotype and allele frequency distributions confirmed the hypothesis that whitefish maturing at small (dwarf) and normal sizes are structured into two distinct gene pools. However, low Fst values at mtDNA and enzyme loci, coupled with the apparent lack of spatial and temporal spawning segregation, suggest that reproductive isolation is incomplete and that gene flow is still occurring between the two forms. Patterns of mtDNA diversity favoured the origin of genetically distinct dwarf and normal-size lake whitefish forms in Lac de l'Est through sympatric divergence. However, a lack of differences in morphological traits potentially related to trophic ecology did not support the hypothesis that the two forms represent ecotypes which are morphologically specialized in trophic niches. This study established that sympatric dwarf and normal-size spawning groups of lake whitefish in Lac de l'Est represent two genetically distinct populations despite the potential for gene flow between them. This, coupled with their low level of morphological diversification, suggests that they represent an early stage of population divergence, and therefore makes them of particular interest for understanding the gene–environment processes involved in the early steps of speciation events.

Evolution of Lake Whitefish (Coregonus clupeaformis) in North America during the Pleistocene: Genetic Differentiation between Sympatric Populations

1992 ◽  
Vol 49 (4) ◽  
pp. 769-779 ◽  
Author(s):  
R. A. Bodaly ◽  
J. W. Clayton ◽  
C. C. Lindsey ◽  
J. Vuorinen
Keyword(s):  
North America ◽  
New England ◽  
Glacial Refugia ◽  
Yukon Territory ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Sympatric Populations ◽  
Sympatric Forms ◽  
Electrophoretic Data ◽  
Glacial Refuge

We use electrophoretic data on dehydrogenase enzymes to examine the relatedness of sympatric populations of lake whitefish (Coregonus clupeaformis) and provide evidence for the existence of a glacial refuge race of lake whitefish in eastern North America. This Acadian race is presently found in New England, the Gaspé peninsula of Québec, and New Brunswick. It probably survived glaciation in a refugium on the exposed coastal plain of northeastern North America. In areas of contact, most glacial races appear to introgress and do not coexist in sympatry. However, sympatric pairs of populations occur (or occurred) within the ranges of all races of lake whitefish. Allele frequencies for at least one enzyme system examined for most sympatric pairs were significantly different, indicating that these sympatric populations are wholly or substantially, isolated reproductively from each other. Both members of the population pairs examined in the Yukon Territory, Ontario, and Labrador were genetically characteristic of the glacial races of their region. This suggests that they are not the result of speciation due to geographic isolation in different glacial refugia. Thus, their origin appears to be postglacial, but may be older if present genetic similarities are due to recent gene flow between sympatric forms.

Spawning of Lake Whitefish, Coregonus clupeaformis, and Round Whiteftsh, Prosopium cylindraceum, in Aishihik Lake and East Aishihik River, Yukon Territory

1975 ◽  
Vol 32 (2) ◽  
pp. 283-288 ◽  
Author(s):  
J. E. Bryan ◽  
D. A. Kato
Keyword(s):  
Yukon Territory ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Hydroelectric Development ◽  
Spawning Grounds ◽  
Spawning Period

Spawning grounds used by lake (Coregonus clupeaformis) and round whitefish (Prosopium cylindraceum) were discovered in the course of an investigation on effects of hydroelectric development. The spawning period for lake whitefish extended from early November to at least mid-December 1973. Lake whitefish spawned over silt and Potomogeton in water which had little current and was 2.0–2.5 m deep. Spawning of round whitefish was probably completed in November. Round whitefish spawned during the day. Eggs were apparently broadcast over a variety of substrata ranging from silt and Potamogeton to gravel and boulder. Round whitefish eggs were deposited in both fast and slow current at depths ranging from 0.7 to 2.5 m. Although deposited in a range of habitats, round whitefish eggs seemed to be most abundant on gravel in fast current at depths less than 1 m.

Evolution of Lake Whitefish (Coregonus clupeaformis) in North America during the Pleistocene: Evidence for a Nahanni Glacial Refuge Race in the Northern Cordillera Region

1992 ◽  
Vol 49 (4) ◽  
pp. 760-768 ◽  
Author(s):  
C. J. Foote ◽  
J. W. Clayton ◽  
C. C. Lindsey ◽  
R. A. Bodaly
Keyword(s):  
Northwest Territories ◽  
National Park ◽  
Yukon Territory ◽  
Glacial Refugium ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Geological Evidence ◽  
Athabasca River ◽  
Peace River ◽  
Glacial Refuge

Lake whitefish (Coregonus clupeaformis) could have survived through (at least) the Illinoisan and Wisconsinan Pleistocene glacial maxima in an area in the vicinity of the present Nahanni National Park in the Northwest Territories of Canada according to the geological evidence. This possibility was addressed by an analysis of the genetic makeup of 43 lake whitefish populations in the Northwest Territories, the Yukon Territory, British Columbia, and Alberta. Populations in the lower Liard, Tetcela, Fraser, and upper Peace River systems as well as the headwaters of the Athabasca River were distinguished from both the Bering glacial refuge race populations inhabiting the Yukon and upper Liard River basins in the Yukon Territory and the Mississippi–Missouri glacial refuge race populations inhabiting most of the Northwest Territories, Alberta, and areas further to the east by a specific combination of electrophoretic mobility alleles. This evidence supports the hypothesis of the survival and subsequent dispersal of lake whitefish from a Nahanni glacial refugium. Possible dispersal routes and the limited extent of introgression among races are discussed.

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