Papers by Svein-erik Fevolden
Ecology and Evolution, 2013
Understanding how a monophyletic lineage of a species diverges into several adaptive forms has re... more Understanding how a monophyletic lineage of a species diverges into several adaptive forms has received increased attention in recent years, but the underlying mechanisms in this process are still under debate. Postglacial fishes are excellent model organisms for exploring this process, especially the initial stages of ecological speciation, as postglacial lakes represent replicated discrete environments with variation in available niches. Here, we combine data of niche utilization, trophic morphology, and 17 microsatellite loci to investigate the diversification process of three sympatric European whitefish morphs from three northern Fennoscandian lakes. The morphological divergence in the gill raker number among the whitefish morphs was related to the utilization of different trophic niches and was associated with reproductive isolation within and across lakes. The intralacustrine comparison of whitefish morphs showed that these systems represent two levels of adaptive divergence: (1) a consistent littoral-pelagic resource axis; and (2) a more variable littoral-profundal resource axis. The results also indicate that the profundal whitefish morph has diverged repeatedly from the ancestral littoral whitefish morph in sympatry in two different watercourses. In contrast, all the analyses performed revealed clustering of the pelagic whitefish morphs across lakes suggesting parallel postglacial immigration with the littoral whitefish morph into each lake. Finally, the analyses strongly suggested that the trophic adaptive trait, number of gill rakers, was under diversifying selection in the different whitefish morphs. Together, the results support a complex evolutionary scenario where ecological speciation acts, but where both allopatric (colonization history) and sympatric (within watercourse divergence) processes are involved. 4970
Fevolden S-E, Martinez I, Christiansen JS. 1999. RAPD and scnDNA analyses of polar cod, Boreogadu... more Fevolden S-E, Martinez I, Christiansen JS. 1999. RAPD and scnDNA analyses of polar cod, Boreogadus saida (Pisces, Gadidae) in the North Atlantic. Sarsia 84:99-103. Polar cod exhibits variation over its distributional area both in morphometry, coloration and behaviour. Samples of polar cod from the Pechora Sea, off Svalbard (Spitsbergen), and from the Denmark Strait, previously analyzed for variation at a series of allozymic loci plus at one scnDNA locus (Syp I), have now been subjected to arbitrary amplification of polymorphic DNA (RAPD-analysis). Polar cod from two extra sampling sites, Disko Bay (western Greenland) and the Porsangerfjord (northern Norway), have been analyzed for Syp I variation. The RAPD approach revealed extensive within-area polymorphism but insignificant between-area variation. The Syp I analyses revealed only two deviant specimens, one from Disko Bay, the other from the Porsangerfjord. In accordance with the previous survey, the present results provide no evidence of any population differentiation of polar cod in the investigated area.
BMC Genetics, 2008
BACKGROUND: The Atlantic cod (Gadus morhua) is a groundfish of great economic value in fisheries ... more BACKGROUND: The Atlantic cod (Gadus morhua) is a groundfish of great economic value in fisheries and an emerging species in aquaculture. Genetic markers are needed to identify wild stocks in order to ensure sustainable management, and for marker-assisted selection and pedigree determination in aquaculture. Here, we report on the development and evaluation of a large number of Single Nucleotide Polymorphism
Ecology and Evolution, 2013
Understanding how a monophyletic lineage of a species diverges into several adaptive forms has re... more Understanding how a monophyletic lineage of a species diverges into several adaptive forms has received increased attention in recent years, but the underlying mechanisms in this process are still under debate. Postglacial fishes are excellent model organisms for exploring this process, especially the initial stages of ecological speciation, as postglacial lakes represent replicated discrete environments with variation in available niches. Here, we combine data of niche utilization, trophic morphology, and 17 microsatellite loci to investigate the diversification process of three sympatric European whitefish morphs from three northern Fennoscandian lakes. The morphological divergence in the gill raker number among the whitefish morphs was related to the utilization of different trophic niches and was associated with reproductive isolation within and across lakes. The intralacustrine comparison of whitefish morphs showed that these systems represent two levels of adaptive divergence: (1) a consistent littoral-pelagic resource axis; and (2) a more variable littoral-profundal resource axis. The results also indicate that the profundal whitefish morph has diverged repeatedly from the ancestral littoral whitefish morph in sympatry in two different watercourses. In contrast, all the analyses performed revealed clustering of the pelagic whitefish morphs across lakes suggesting parallel postglacial immigration with the littoral whitefish morph into each lake. Finally, the analyses strongly suggested that the trophic adaptive trait, number of gill rakers, was under diversifying selection in the different whitefish morphs. Together, the results support a complex evolutionary scenario where ecological speciation acts, but where both allopatric (colonization history) and sympatric (within watercourse divergence) processes are involved.
Plos One, 2014
Invasion of exotic species has caused the loss of biodiversity and imparts evolutionary and ecolo... more Invasion of exotic species has caused the loss of biodiversity and imparts evolutionary and ecological changes in the introduced systems. In northern Fennoscandia, European whitefish (Coregonus lavaretus (L.)) is a highly polymorphic species displaying adaptive radiations into partially reproductively isolated and thus genetically differentiated sympatric morphs utilizing the planktivorous and benthivorous food niche in many lakes. In 1993, Lake Skrukkebukta was invaded by vendace (Coregonus albula (L.)) which is a zooplanktivorous specialist. The vendace displaced the densely rakered whitefish from its preferred pelagic niche to the benthic habitat harbouring the large sparsely rakered whitefish. In this study, we investigate the potential influence of the vendace invasion on the breakdown of reproductive isolation between the two whitefish morphs. We inferred the genotypic and phenotypic differentiation between the two morphs collected at the arrival (1993) and 15 years after (2008) the vendace invasion using 16 microsatellite loci and gill raker numbers, the most distinctive adaptive phenotypic trait between them. The comparison of gill raker number distributions revealed two modes growing closer over 15 years following the invasion. Bayesian analyses of genotypes revealed that the two genetically distinct whitefish morphs that existed in 1993 had collapsed into a single population in 2008. The decline in association between the gill raker numbers and admixture values over 15 years corroborates the findings from the Bayesian analysis. Our study thus suggests an apparent decrease of reproductive isolation in a morph-pair of European whitefish within 15 years (≃ 3 generations) following the invasion of a superior trophic competitor (vendace) in a subarctic lake, reflecting a situation of "speciation in reverse".
Polar Biology, 2009
... saida (Lepechin, 1774) Matias L. Madsen · Svein-Erik Fevolden · Jørgen S. Christiansen Receiv... more ... saida (Lepechin, 1774) Matias L. Madsen · Svein-Erik Fevolden · Jørgen S. Christiansen Received: 3 February 2009 / Revised: 10 March 2009 / Accepted: 11 March 2009 / Published online: 27 March 2009 © Springer-Verlag 2009 ... No. AF159238) (Miller et al. ...
Polar Biology, 2006
Population structure, growth and body composition (wet-, dry-, ash weight and total lipid) of the... more Population structure, growth and body composition (wet-, dry-, ash weight and total lipid) of the Arctic pelagic amphipod Themisto libellula were studied in four fjords on West Spitsbergen, Svalbard, from July to December 2000 and in April 2002. In one of the fjords, Kongsfjorden, growth of T. libellula was calculated as the change in mean length of the 0+ cohort
Molecular Ecology, 2002
To examine the role of contemporary selection in maintaining significant allele frequency differe... more To examine the role of contemporary selection in maintaining significant allele frequency differences at the pantophysin (PanI) locus among populations of the Atlantic cod, Gadus morhua, in northern Norway, we sequenced 127 PanIA alleles sampled from six coastal and two Barents Sea populations. The distributions of variable sites segregating within the PanIA allelic class were then compared among the populations. Significant differences were detected in the overall frequencies of PanIA alleles among populations within coastal and Arctic regions that was similar in magnitude to heterogeneity in the distributions of polymorphic sites segregating within the PanIA allelic class. The differentiation observed at silent sites in the PanIA allelic class contradicts the predicted effects of widescale gene flow and suggests that postsettlement selection acting on cohorts cannot be responsible for the genetic differences described between coastal and Arctic populations. Our results suggest that the marked differences observed between coastal and Arctic populations of G. morhua in northern Norway at the PanI locus reflect the action of recent diversifying selection and that populations throughout the region may be more independent than suggested by previous studies.
Marine Biology Research, 2009
To cite this Article Praebel, Kim, Christiansen, Jørgen S. and Fevolden, Svein-Erik(2009)'Tempera... more To cite this Article Praebel, Kim, Christiansen, Jørgen S. and Fevolden, Svein-Erik(2009)'Temperature and salinity conditions in a sub-Arctic intertidal spawning habitat for capelin',Marine Biology Research,99999:1, To link to this Article:
Journal of Fish Biology, 1993
... specific anti-body against Vibrio anguiilarum O-antigen (Va), Vibrio saìmonicida O-antigen (V... more ... specific anti-body against Vibrio anguiilarum O-antigen (Va), Vibrio saìmonicida O-antigen (Vs), Aeromonas saìmonicida A-layer (As), lysozyme and serum haemolytic activities (cf, Materials and Methods) 6 weeks after vaccination against the pathogens {SRI; Table I) Va Vs As ...
Journal of Fish Biology, 1997
Several nuclear RFLP loci have been discovered recently that exhibit extensive allele frequency v... more Several nuclear RFLP loci have been discovered recently that exhibit extensive allele frequency variation among Norwegian coastal and north-east Arctic populations of Atlantic cod Gadus morhua. One of these polymorphisms was detected by hybridizing an anonymous cDNA ...
Hydrobiologia, 2008
Atlantic cod (Gadus morhua) encompasses many different populations or stocks, which in part are m... more Atlantic cod (Gadus morhua) encompasses many different populations or stocks, which in part are managed separately. In the northeast Atlantic cod is divided into two main management units; northeast Arctic cod and coastal cod. These two groups have traditionally been separated by otolith classification. In this study, the power of different classes of genetic markers in separating the two cod
Genetics and Molecular Biology, 2008
The capelin, Mallotus villosus (Osmeriformes, Osmeridae), is an ecological and commercial key com... more The capelin, Mallotus villosus (Osmeriformes, Osmeridae), is an ecological and commercial key component of the sub-arctic ichthyofauna. Here, we provide the first cytogenetic information on the species based on both conventional karyotyping and chromosomal mapping of 45S and 5S ribosomal genes through fluorescence in situ hybridization (FISH). The capelin genome displayed a diploid number of 54 with the karyotypic formula 26m/sm+28st/a and a fundamental number (FN) = 80. Both classes of ribosomal genes appeared to be spread out to multiple chromosomal locations, i.e. the 45S and 5S rDNA clusters were detected on six and seven chromosome pairs, respectively. A linked chromosomal organization of the major and minor ribosomal genes classes has been visualized in most of the rDNAs chromosomal locations. A comparative analysis of the available cytogenetic data for the family Osmeridae reveals diploid numbers higher than 48 and high fundamental numbers. This suggests that a rearranged karyotype is a shared feature within this family.
Fisheries Research, 2005
The genetic population structure of Atlantic cod in Ullsfjord, north Norway, was studied by analy... more The genetic population structure of Atlantic cod in Ullsfjord, north Norway, was studied by analysing allele frequencies at the scnDNA locus pantophysin (Pan I) in 2597 fish. The Pan I frequencies displayed distinct horizontal stratification within the fjord, which persisted over seasons and years. In the spring spawning season, mature cod predominated by the Pan IA allele typical for Norwegian
Fisheries Research, 2007
A large majority of Atlantic cod (Gadus morhua) found all year round in outer parts of fjords and... more A large majority of Atlantic cod (Gadus morhua) found all year round in outer parts of fjords and along outer coastal areas in general in northern Norway have a genetic signature at the pantophysin (Pan I) locus that distinguish them from Norwegian coastal cod (NCC) found further inside fjords in the same areas. The identity of these fish has been controversial and to examine if they represent a distinct coastal cod group, or are identical to the migratory North East Arctic cod (NEAC) of the Barents Sea, a comparison was conducted at 10 microsatellite loci for 15 samples comprising each of the three groups inner coastal NCC, outer coastal cod and NEAC. Spatial analysis of molecular variance revealed that the outer coastal samples cannot be discriminated from NEAC by means of microsatellite markers, supporting the similarity of the two groups at the Pan I locus. This implies that a portion of the otherwise migratory NEAC, at least in its premature stage, remains in coastal areas in close contact with the genetically quite distinct NCC group. Both the coalescent-based simulation approach and the lnRH test for selective sweeps proved two of the microsatellite loci, GMO 34 and GMO 132 to be non-neutral. Notwithstanding, these two loci, together with the acknowledged non-neutral Pan I locus, which displayed profound linkage disequilibrium to GMO 34 within NEAC, are as yet the only nuclear markers which unambiguously discriminate between NEAC and NCC. Although the relative contribution of restricted gene flow versus selection as a causative agent for the divergence between NEAC and NCC has not been assessed, we believe the magnitude of differentiation at the three loci provides rational for maintaining NEAC and NCC as separate management units.
Fisheries Research, 2008
For stock assessment purposes, Atlantic cod (Gadus morhua) from the coastal and offshore regions ... more For stock assessment purposes, Atlantic cod (Gadus morhua) from the coastal and offshore regions off northern Norway is usually allocated to Norwegian coastal cod (NCC) or Northeast Arctic cod (NEAC) by internal morphological features of their otoliths. As this classification is subject to individual interpretation by otolith age readers, this study investigated an alternative objective approach for the separation of the two cod groups, using otolith shape analysis. Several hundred otolith samples from coastal fjord areas along northern Norway and from the Barents Sea were analysed by univariate shape descriptors and elliptical Fourier analysis (EFA). When combining uni-and multivariate descriptors and applying the otolith reader typing as reference, the classification score was 89% for NCC and 90% for NEAC. These results indicate that the internal morphology of the otoliths, evaluated by the age readers, is translated to a great extent to their outer morphology and that otoliths can be allocated to NCC and NEAC by their shapes with high certainty. When genetic typing data (Pan I marker) were used as reference, the classification scores were reduced to 83% for NCC and 76% for NEAC when combining uni-and multivariate descriptors and excluding heterozygotes. This implies that differences in otolith morphology cannot directly be linked to genetic structure. Differences in environmental conditions, however, seem to have a considerable influence on how otolith growth increments and consequently otolith shapes are formed. As the various fjord systems in Norway provide local habitats and as differences within the NCC with regard to genetic structure and life-history parameters had been found in earlier studies, variation of NCC otolith shapes between three coastal regions was also examined. The region classification scores for reader-typed NCC varied between 60% and 81%.
Fish & Shellfish Immunology, 1994
ABSTRACT
Conservation Genetics Resources, 2013
ABSTRACT Three methods for extracting DNA were tested on otoliths, scales, fins, and gill tissue ... more ABSTRACT Three methods for extracting DNA were tested on otoliths, scales, fins, and gill tissue from European whitefish [Coregonus lavaratus (L.)]. The aim was to find time-efficient and affordable ways to simultaneously extract DNA suitable for conservation genetic studies from a large number of samples and different tissues. A rapid low-cost method led to 97 % success of microsatellite amplification in otoliths and 100 % in scales. High amplification success was achieved with fin (97 %) and gill (99 %) tissue using a salt lysis-based protocol. A commercial extraction kit delivered good results with all tissues. The findings are useful for conservation genetic studies using both contemporary and archived samples.
BMC Evolutionary Biology, 2007
The walleye pollock (Theragra chalcogramma) and Norwegian pollock (T. finnmarchica) are confined ... more The walleye pollock (Theragra chalcogramma) and Norwegian pollock (T. finnmarchica) are confined to the North Pacific and North Atlantic Oceans, respectively, and considered as distinct species within the family Gadidae. We have determined the complete mtDNA nucleotide sequence of two specimens of Norwegian pollock and compared the sequences to that of 10 specimens of walleye pollock representing stocks from the Sea of Japan and the Bering Sea, 2 specimens of Atlantic cod (Gadus morhua), and 2 specimens of haddock (Melanogrammus aeglefinus).
Aquatic Living Resources, 2000
In order to elucidate the population structure of the deep-sea shrimp (Pandalus borealis) in the ... more In order to elucidate the population structure of the deep-sea shrimp (Pandalus borealis) in the NE Atlantic, 32 subsamples and 3 865 individuals were analysed for allozymic variation. They were caught at various locations in the Barents Sea, in waters off Svalbard, Jan Mayen and Iceland, and in fjords along the Norwegian coast. Only three enzymes (malate dehydrogenase, phosphoglucomutase and glucosephosphate isomerase) of the 22 initially tested showed a combination of gel images that could be interpreted with confidence and allozymic variation. The locus coding for malate dehydrogenase was by far the most polymorphic. Samples caught within the Barents Sea and in the Svalbard area showed no significant heterogeneity in allele frequencies, supporting earlier suggestions of only one population of P. borealis in the Barents Sea. Genetic differentiation was found, however, between Norwegian fjords and the Barents Sea, and among fjords.
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Papers by Svein-erik Fevolden