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

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.

2017 ◽  
Vol 69 ◽  
pp. 294-301 ◽  
Author(s):  
Lindy M. Whitehouse ◽  
Chance S. McDougall ◽  
Daniel I. Stefanovic ◽  
Douglas R. Boreham ◽  
Christopher M. Somers ◽  
...  

1977 ◽  
Vol 34 (5) ◽  
pp. 617-625 ◽  
Author(s):  
W. G. Franzin ◽  
J. W. Clayton

Frequencies of alleles of the genes governing electrophoretic phenotypes of lake whitefish (Coregonus clupeaformis) muscle glycerol-3-phosphate dehydrogenase (G-3-PDH) and lactate dehydrogenase (LDH) enzymes, the genetics of which were determined previously, proved useful tools for characterizing populations. Malate dehydrogenase (MDH) and hemoglobin electrophoretic phenotypes, the genetics of which have not been determined, proved useful only for discerning differences among large groups of populations. Using all these characters we determined postglacial routes of gene flow among western Canadian lake whitefish populations and related the biochemical data to the glacial refugia in which lake whitefish are believed to have survived the Wisconsin glaciation. Apparently most lake whitefish populations west of the Ontario–Manitoba boundary and east of the Rocky Mountains were derived from a Mississippi refugium stock with some input from the Bering refugium. At an early stage in the mixing of the two stocks, headwaters of the Peace, Athabasca, and Mackenzie rivers and the Fraser River system were invaded. Subsequently, these areas were cut off from mainstem rivers of the plains, and a G-3-PDH allele not found in early emigrants from the Mississippi refugium appeared and spread throughout the major river systems of central Canada. No evidence was found that any Mississippi stock lake whitefish were able to invade the upper Liard River and Yukon River system including the area of the Bering refugium. Bering stock lake whitefish probably emigrated from that refugium by way of headwater transfer from the Yukon River to the Liard River and possibly, by way of the Porcupine and Peel rivers, from the Yukon River to the lower Mackenzie River. Routes of postglacial dispersal suggested by geological information, rather than selection, appear to provide adequate explanations for the distributions of the biochemical characters in present day lake whitefish populations. This explanation of the biochemical data is also in accord with the distribution of modal gillraker counts in lake whitefish populations and also with the distribution of other freshwater fishes in western Canada. Key words: fish, lake whitefish, Coregonus clupeaformis, salmonidae, zoogeography, dehydrogenase, postglacial, biochemical genetics


1981 ◽  
Vol 38 (12) ◽  
pp. 1497-1506 ◽  
Author(s):  
C. C. Lindsey

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


2019 ◽  
Vol 76 (8) ◽  
pp. 1411-1422 ◽  
Author(s):  
T.A. Johnston ◽  
A.D. Ehrman ◽  
G.L. Hamilton ◽  
B.K. Nugent ◽  
P.A. Cott ◽  
...  

Realized trophic niches of aquatic consumers are expected to reflect the particular abiotic and biotic conditions of the ecosystems they occupy. We examined patterns in the position, size, and shape of trophic niches of two common benthivorous fishes, white sucker (Catostomus commersonii) and lake whitefish (Coregonus clupeaformis), across boreal lakes using a stable isotope approach. In sympatry, white sucker niche positions reflected greater benthic reliance (higher δ13C) and lower trophic elevation (lower δ15N) compared with lake whitefish, and white sucker niche sizes (dispersion in δ13C–δ15N space) were also larger. Niche sizes of both species increased with maximum depth of lakes. Separation of trophic niche positions of the two species increased with increasing water clarity, but their niche sizes did not increase with increasing separation in their niche positions. White sucker occupied a niche position with slightly greater pelagic reliance and trophic elevation and had smaller trophic niches in the absence than in the presence of lake whitefish. Trophic niches of these benthivores appear to be shaped by both environmental factors and interspecific interactions.


2017 ◽  
Vol 108 (3) ◽  
pp. 288-298 ◽  
Author(s):  
María José Sanín ◽  
Patricia Zapata ◽  
Jean-Christophe Pintaud ◽  
Gloria Galeano ◽  
Adriana Bohórquez ◽  
...  

1975 ◽  
Vol 32 (3) ◽  
pp. 404-407 ◽  
Author(s):  
M. C. Healey ◽  
C. W. Nicol

We found no significant differences in slope or intercept for the regression of loge fecundity on loge fork length among samples of whitefish from four lakes near Yellowknife in the Northwest Territories. The equation describing the relationship between fecundity and fork length for these populations was:[Formula: see text]Five other populations for which length–fecundity relationships could be calculated had length exponents ranging from 3.20 to 4.38, suggesting a nonlinear relationship between weight and fecundity. Six of the nine populations as well as four others for which limited data were available all had similar relative fecundities. Fish from Buck Lake in Alberta and from Lake Erie had high relative fecundities while fish from Great Slave Lake had low relative fecundity.


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