Eric Verspoor | University of the Highlands and Islands - UHI (original) (raw)
Papers by Eric Verspoor
North American Journal of Fisheries Management, 2000
An incubator was designed and field tested for monitoring eggs of Atlantic salmon Salmo salar pla... more An incubator was designed and field tested for monitoring eggs of Atlantic salmon Salmo salar planted out in streams. It is robust, reusable, and could be adapted to accommodate the eggs of other salmonids. It comprises eight individual incubation trays within a portable wire basket that inserts into a frame installed in or on the streambed. Each tray can accommodate
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Journal of Fish Biology, 1997
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Canadian Journal of Zoology-revue Canadienne De Zoologie, 1987
ABSTRACT Within- and between-year variation in incubation and chick-brooding shift duration were ... more ABSTRACT Within- and between-year variation in incubation and chick-brooding shift duration were studied during the 1981–1983 breeding seasons in Common Murre, Uria aalge, pairs on the Gannet Islands, Labrador. Incubation shifts averaged 17 h (range: 1–38 h) and daytime brooding shifts, 4 h (range: 1–14 h). Brooding shifts that included the night, during which change-overs did not occur, averaged 12 h (range: 7–20 h). No differences in shift duration were detected between the sexes but females incubated more at night than did males and were more likely to initiate their incubation shifts in early morning or late evening than males. There was no evidence that pairs tended to change over at the same time each day or that change-overs of neighbouring pairs were synchronized. Shift duration during chick rearing showed significant differences between 1982 and 1983 and the possibility that this was in response to differences in food availability is discussed.
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Journal of Fish Biology, 2006
Spatial variation at the diallelic Me-2 locus in the Atlantic salmon, Salmo salar L., was analyse... more Spatial variation at the diallelic Me-2 locus in the Atlantic salmon, Salmo salar L., was analysed using data from 95 river basins. Gene diversity was apportioned as follows: 63% within samples, 20% between North America and Europe, 14% between regions within continents and 3% within and among rivers within regions. On both continents the variation between rivers was clinal with latitude and highly correlated with summer temperatures. The correlation was detectable within and between rivers. These correlations strongly suggest that variation at the locus is subject to the direct or indirect effects of natural selection, and that caution is required when interpreting between-location differentiation at the locus as evidence for distinct stocks.
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Biochemical Genetics, 1994
Electrophoretic studies of malate oxidoreductases routinely assess variation in two enzymes, mala... more Electrophoretic studies of malate oxidoreductases routinely assess variation in two enzymes, malate dehydrogenase (EC 1.1.1.37) and malic enzyme (NADP+) (EC 1.1.1.40). By modification of the standard isozyme staining conditions for these enzymes, we have resolved a new NAD+-preferring, MgCl2-requiring malic enzyme which is indicated to be EC 1.1.1.39. The enzyme was detected in 10 salmonid fish species of the generaSalmo, Salvelinus, andOnchoryhncus. Phenotypic variation indicates that the novel enzyme is tetrameric and coded by a single locus. Inheritance inS. salar follows a single-locus model and the phenotypes are unlinked to polymorphisms forsMDH-3,4* andmMEP-2*, two malate oxidoreductase loci previously shown to be variable in this species.
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Biological Journal of The Linnean Society, 1999
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Biological Reviews, 2007
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Canadian Journal of Fisheries and Aquatic Sciences, 1998
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Animal Genetics, 2004
A linkage map of the Atlantic salmon is described here consisting of 15 linkage groups containing... more A linkage map of the Atlantic salmon is described here consisting of 15 linkage groups containing 50 microsatellite loci with a 14 additional unlinked markers (including three allozymes). The map shows the largest sex-specific recombination rate differences so far found in any vertebrate species (3.92:1 female:male). Homologies with previous linkage mapping studies of Atlantic salmon and rainbow trout are described. An in silico search of the Genbank database carried out using the microsatellites used in the mapping process identified significant matches between the flanking regions of the microsatellite SS11 and the calcium-binding mitochondrial carrier protein, ‘Aralar1’.
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Molecular Ecology, 2002
Current understanding of the postglacial colonization of Nearctic and Palearctic species relies h... more Current understanding of the postglacial colonization of Nearctic and Palearctic species relies heavily on inferences drawn from the phylogeographic analysis of contemporary generic variants. Modern postglacial populations are supposed to be representative of their Pleistocene ancestors, and their current distribution is assumed to reflect the different colonization success and dispersal patterns of refugial lineages. Yet, testing of phylogeographic models against ancestral genomes from glacial refugia has rarely been possible. Here we compare ND1 mitochondrial DNA variation in late Pleistocene (16,000-40,000 years before present), historical and contemporary Atlantic salmon (Salmo salar) populations from northern Spain and other regions of western Europe. Our study demonstrates the presence of Atlantic salmon in the Iberian glacial refugium during the last 40,000 years and points to the Iberian Peninsula as the likely source of the most common haplotype within the Atlantic lineage in Europe. However, our findings also suggest that there may have been significant changes in the genetic structure of the Iberian refugial stock since the last ice age, and question whether modern populations in refugial areas are representative of ice age populations. A common haplotype that persisted in the Iberian Peninsula during the Pleistocene last glacial maximum is now extremely rare or absent from European rivers, highlighting the need for caution when making phylogeographic inferences about the origin and distribution of modern genetic types.
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Biological Journal of The Linnean Society, 1999
The diversity and distribution of mtDNA haplotypes in Atlantic salmon (Salmo salar L.) from 13 ri... more The diversity and distribution of mtDNA haplotypes in Atlantic salmon (Salmo salar L.) from 13 river systems across the species' European range was investigated. Salmon were screened by agarose electrophoresis for variation in a 1400 base pair fragment spanning the ND-1 and 16SrRNA genes. The fragment was amplified by PCR and digested using the restriction endonucleases Avail, Dral, Haelll, Hinfl and Rsal. Nine haplotypes were identified and resolved by parsimony analysis into two major clades. Clade I was ubiquitous and predominated in all samples while Clade II was restricted to eight out of 94 individuals in two of the 13 rivers. The first clade shows two sublineages whose frequency distribution is strongly associated with geography. One sublineage dominated in river systems draining into the Baltic sea and in Iceland, and the other in the river systems elsewhere in Europe. No geographical patterns were apparent within these regions but haplotype frequencies among samples, both within and outside the Baltic region, were significantly heterogeneous. Approximately 8% of haplotype frequency variation occurred among samples, 44% between Baltic and non-Baltic samples and 48% within samples. Baltic samples had a significantly lower haplotype and nucleotide diversity than non-Baltic samples. Current and historical factors potentially responsible for the observed levels and distribution of the haplotype variation are discussed.
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Canadian Journal of Fisheries and Aquatic Sciences, 1995
Abstract: A highly discriminatory and practical nuclear DNA genetic marker that can distinguish b... more Abstract: A highly discriminatory and practical nuclear DNA genetic marker that can distinguish between Atlantic salmon (Salmo salar) of European and North American origin is described. Screening of 2847 European and 247 North American Atlantic salmon from much of its ...
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Journal of Fish Biology, 1997
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Ices Journal of Marine Science, 1997
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Fisheries Research, 2003
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Molecular Ecology Notes, 2004
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Journal of Fish Biology, 2005
Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in ... more Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in many species including the Atlantic salmon Salmo salar, one of the most culturally and economically important fish species of the North Atlantic region. Since 1966, >350 scientific papers on protein variation have been published encompassing 25 000+ salmon from over 400 locations in >200 river systems across the species’ distribution. Variation has been detected at 30% of the 110 protein loci screened, though most studies examine <40. The method has been applied largely to the investigation of population structure and differentiation, but work has also led to the systematic revision of the genus Salmo and remains the primary source of insight into hybridization in the wild with brown trout Salmo trutta. Spatial patterns of differentiation show temporal stability, both within and among river systems, and strongly support structuring of the species into river and tributary specific populations and the designation of European and North American populations as distinct sub-species. They also show widespread regional differentiation within both continents, beyond the marked subcontinental differences between Baltic Sea and Atlantic Ocean populations in Europe. Most of the differentiation probably reflects gene flow and founder events associated with colonization following the retreat of the glaciers from much of the species’ modern range. However, variation at MEP-2* shows strong correlations with environmental temperature, both within and among rivers, and associations with phenotypic performance. This suggests selection is acting on the locus and provides compelling evidence for the local adaptation of populations. Protein studies have led to more population centred management of the species and have been exploited in the discrimination of regional stocks in mixed stock analysis in high seas fisheries, particularly in the Baltic Sea, and as markers for the assessment of stocking success. They have also advanced insight into how the genetic character of populations can be changed in cultivation and the potential impact of salmon aquaculture and stocking on wild populations. The method has been largely superseded by DNA based analyses, but the results remain highly relevant to Atlantic salmon management and conservation and are an irreplaceable data set for studying genetic stability of populations over time.
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Conservation Genetics, 2005
Small populations may be expected to harbour less genetic variation than large populations, but t... more Small populations may be expected to harbour less genetic variation than large populations, but the relation between census size (N), effective population size (N e), and genetic diversity is not well understood. We compared microsatellite variation in four small peripheral Atlantic salmon populations from the Iberian peninsula and three larger populations from Scotland to test whether genetic diversity was related to population size. We also examined the historical decline of one Iberian population over a 50-year period using archival scales in order to test whether a marked reduction in abundance was accompanied by a decrease in genetic diversity. Estimates of effective population size (N e) calculated by three temporal methods were consistently low in Iberian populations, ranging from 12 to 31 individuals per generation considering migration, and from 38 to 175 individuals per generation if they were regarded as closed populations. Corresponding N e/N ratios varied from 0.02 to 0.04 assuming migration (mean=0.03) and from 0.04 to 0.18 (mean=0.10) assuming closed populations. Population bottlenecks, inferred from the excess of heterozygosity in relation to allelic diversity, were detected in all four Iberian populations, particularly in those year classes derived from a smaller number of returning adults. However, despite their small size and declining status, Iberian populations continue to display relatively high levels of heterozygosity and allelic richness, similar to those found in larger Scottish populations. Furthermore, in the R. Asón no evidence was found for a historical loss of genetic diversity despite a marked decline in abundance during the last five decades. Thus, our results point to two familiar paradigms in salmonid conservation: (1)␣endangered populations can maintain relatively high levels of genetic variation despite their small size, and (2) marked population declines may not necessarily result in a significant loss of genetic diversity. Although there are several explanations for such results, microsatellite data and physical tagging suggest that high levels of dispersal and asymmetric gene flow have probably helped to maintain genetic diversity in these peripheral populations, and thus to avoid the negative consequences of inbreeding.
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Heredity, 2002
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North American Journal of Fisheries Management, 2000
An incubator was designed and field tested for monitoring eggs of Atlantic salmon Salmo salar pla... more An incubator was designed and field tested for monitoring eggs of Atlantic salmon Salmo salar planted out in streams. It is robust, reusable, and could be adapted to accommodate the eggs of other salmonids. It comprises eight individual incubation trays within a portable wire basket that inserts into a frame installed in or on the streambed. Each tray can accommodate
Bookmarks Related papers MentionsView impact
Journal of Fish Biology, 1997
Bookmarks Related papers MentionsView impact
Canadian Journal of Zoology-revue Canadienne De Zoologie, 1987
ABSTRACT Within- and between-year variation in incubation and chick-brooding shift duration were ... more ABSTRACT Within- and between-year variation in incubation and chick-brooding shift duration were studied during the 1981–1983 breeding seasons in Common Murre, Uria aalge, pairs on the Gannet Islands, Labrador. Incubation shifts averaged 17 h (range: 1–38 h) and daytime brooding shifts, 4 h (range: 1–14 h). Brooding shifts that included the night, during which change-overs did not occur, averaged 12 h (range: 7–20 h). No differences in shift duration were detected between the sexes but females incubated more at night than did males and were more likely to initiate their incubation shifts in early morning or late evening than males. There was no evidence that pairs tended to change over at the same time each day or that change-overs of neighbouring pairs were synchronized. Shift duration during chick rearing showed significant differences between 1982 and 1983 and the possibility that this was in response to differences in food availability is discussed.
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Journal of Fish Biology, 2006
Spatial variation at the diallelic Me-2 locus in the Atlantic salmon, Salmo salar L., was analyse... more Spatial variation at the diallelic Me-2 locus in the Atlantic salmon, Salmo salar L., was analysed using data from 95 river basins. Gene diversity was apportioned as follows: 63% within samples, 20% between North America and Europe, 14% between regions within continents and 3% within and among rivers within regions. On both continents the variation between rivers was clinal with latitude and highly correlated with summer temperatures. The correlation was detectable within and between rivers. These correlations strongly suggest that variation at the locus is subject to the direct or indirect effects of natural selection, and that caution is required when interpreting between-location differentiation at the locus as evidence for distinct stocks.
Bookmarks Related papers MentionsView impact
Biochemical Genetics, 1994
Electrophoretic studies of malate oxidoreductases routinely assess variation in two enzymes, mala... more Electrophoretic studies of malate oxidoreductases routinely assess variation in two enzymes, malate dehydrogenase (EC 1.1.1.37) and malic enzyme (NADP+) (EC 1.1.1.40). By modification of the standard isozyme staining conditions for these enzymes, we have resolved a new NAD+-preferring, MgCl2-requiring malic enzyme which is indicated to be EC 1.1.1.39. The enzyme was detected in 10 salmonid fish species of the generaSalmo, Salvelinus, andOnchoryhncus. Phenotypic variation indicates that the novel enzyme is tetrameric and coded by a single locus. Inheritance inS. salar follows a single-locus model and the phenotypes are unlinked to polymorphisms forsMDH-3,4* andmMEP-2*, two malate oxidoreductase loci previously shown to be variable in this species.
Bookmarks Related papers MentionsView impact
Biological Journal of The Linnean Society, 1999
Bookmarks Related papers MentionsView impact
Biological Reviews, 2007
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Canadian Journal of Fisheries and Aquatic Sciences, 1998
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Animal Genetics, 2004
A linkage map of the Atlantic salmon is described here consisting of 15 linkage groups containing... more A linkage map of the Atlantic salmon is described here consisting of 15 linkage groups containing 50 microsatellite loci with a 14 additional unlinked markers (including three allozymes). The map shows the largest sex-specific recombination rate differences so far found in any vertebrate species (3.92:1 female:male). Homologies with previous linkage mapping studies of Atlantic salmon and rainbow trout are described. An in silico search of the Genbank database carried out using the microsatellites used in the mapping process identified significant matches between the flanking regions of the microsatellite SS11 and the calcium-binding mitochondrial carrier protein, ‘Aralar1’.
Bookmarks Related papers MentionsView impact
Molecular Ecology, 2002
Current understanding of the postglacial colonization of Nearctic and Palearctic species relies h... more Current understanding of the postglacial colonization of Nearctic and Palearctic species relies heavily on inferences drawn from the phylogeographic analysis of contemporary generic variants. Modern postglacial populations are supposed to be representative of their Pleistocene ancestors, and their current distribution is assumed to reflect the different colonization success and dispersal patterns of refugial lineages. Yet, testing of phylogeographic models against ancestral genomes from glacial refugia has rarely been possible. Here we compare ND1 mitochondrial DNA variation in late Pleistocene (16,000-40,000 years before present), historical and contemporary Atlantic salmon (Salmo salar) populations from northern Spain and other regions of western Europe. Our study demonstrates the presence of Atlantic salmon in the Iberian glacial refugium during the last 40,000 years and points to the Iberian Peninsula as the likely source of the most common haplotype within the Atlantic lineage in Europe. However, our findings also suggest that there may have been significant changes in the genetic structure of the Iberian refugial stock since the last ice age, and question whether modern populations in refugial areas are representative of ice age populations. A common haplotype that persisted in the Iberian Peninsula during the Pleistocene last glacial maximum is now extremely rare or absent from European rivers, highlighting the need for caution when making phylogeographic inferences about the origin and distribution of modern genetic types.
Bookmarks Related papers MentionsView impact
Biological Journal of The Linnean Society, 1999
The diversity and distribution of mtDNA haplotypes in Atlantic salmon (Salmo salar L.) from 13 ri... more The diversity and distribution of mtDNA haplotypes in Atlantic salmon (Salmo salar L.) from 13 river systems across the species' European range was investigated. Salmon were screened by agarose electrophoresis for variation in a 1400 base pair fragment spanning the ND-1 and 16SrRNA genes. The fragment was amplified by PCR and digested using the restriction endonucleases Avail, Dral, Haelll, Hinfl and Rsal. Nine haplotypes were identified and resolved by parsimony analysis into two major clades. Clade I was ubiquitous and predominated in all samples while Clade II was restricted to eight out of 94 individuals in two of the 13 rivers. The first clade shows two sublineages whose frequency distribution is strongly associated with geography. One sublineage dominated in river systems draining into the Baltic sea and in Iceland, and the other in the river systems elsewhere in Europe. No geographical patterns were apparent within these regions but haplotype frequencies among samples, both within and outside the Baltic region, were significantly heterogeneous. Approximately 8% of haplotype frequency variation occurred among samples, 44% between Baltic and non-Baltic samples and 48% within samples. Baltic samples had a significantly lower haplotype and nucleotide diversity than non-Baltic samples. Current and historical factors potentially responsible for the observed levels and distribution of the haplotype variation are discussed.
Bookmarks Related papers MentionsView impact
Canadian Journal of Fisheries and Aquatic Sciences, 1995
Abstract: A highly discriminatory and practical nuclear DNA genetic marker that can distinguish b... more Abstract: A highly discriminatory and practical nuclear DNA genetic marker that can distinguish between Atlantic salmon (Salmo salar) of European and North American origin is described. Screening of 2847 European and 247 North American Atlantic salmon from much of its ...
Bookmarks Related papers MentionsView impact
Journal of Fish Biology, 1997
Bookmarks Related papers MentionsView impact
Ices Journal of Marine Science, 1997
Bookmarks Related papers MentionsView impact
Fisheries Research, 2003
Bookmarks Related papers MentionsView impact
Molecular Ecology Notes, 2004
Bookmarks Related papers MentionsView impact
Journal of Fish Biology, 2005
Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in ... more Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in many species including the Atlantic salmon Salmo salar, one of the most culturally and economically important fish species of the North Atlantic region. Since 1966, >350 scientific papers on protein variation have been published encompassing 25 000+ salmon from over 400 locations in >200 river systems across the species’ distribution. Variation has been detected at 30% of the 110 protein loci screened, though most studies examine <40. The method has been applied largely to the investigation of population structure and differentiation, but work has also led to the systematic revision of the genus Salmo and remains the primary source of insight into hybridization in the wild with brown trout Salmo trutta. Spatial patterns of differentiation show temporal stability, both within and among river systems, and strongly support structuring of the species into river and tributary specific populations and the designation of European and North American populations as distinct sub-species. They also show widespread regional differentiation within both continents, beyond the marked subcontinental differences between Baltic Sea and Atlantic Ocean populations in Europe. Most of the differentiation probably reflects gene flow and founder events associated with colonization following the retreat of the glaciers from much of the species’ modern range. However, variation at MEP-2* shows strong correlations with environmental temperature, both within and among rivers, and associations with phenotypic performance. This suggests selection is acting on the locus and provides compelling evidence for the local adaptation of populations. Protein studies have led to more population centred management of the species and have been exploited in the discrimination of regional stocks in mixed stock analysis in high seas fisheries, particularly in the Baltic Sea, and as markers for the assessment of stocking success. They have also advanced insight into how the genetic character of populations can be changed in cultivation and the potential impact of salmon aquaculture and stocking on wild populations. The method has been largely superseded by DNA based analyses, but the results remain highly relevant to Atlantic salmon management and conservation and are an irreplaceable data set for studying genetic stability of populations over time.
Bookmarks Related papers MentionsView impact
Conservation Genetics, 2005
Small populations may be expected to harbour less genetic variation than large populations, but t... more Small populations may be expected to harbour less genetic variation than large populations, but the relation between census size (N), effective population size (N e), and genetic diversity is not well understood. We compared microsatellite variation in four small peripheral Atlantic salmon populations from the Iberian peninsula and three larger populations from Scotland to test whether genetic diversity was related to population size. We also examined the historical decline of one Iberian population over a 50-year period using archival scales in order to test whether a marked reduction in abundance was accompanied by a decrease in genetic diversity. Estimates of effective population size (N e) calculated by three temporal methods were consistently low in Iberian populations, ranging from 12 to 31 individuals per generation considering migration, and from 38 to 175 individuals per generation if they were regarded as closed populations. Corresponding N e/N ratios varied from 0.02 to 0.04 assuming migration (mean=0.03) and from 0.04 to 0.18 (mean=0.10) assuming closed populations. Population bottlenecks, inferred from the excess of heterozygosity in relation to allelic diversity, were detected in all four Iberian populations, particularly in those year classes derived from a smaller number of returning adults. However, despite their small size and declining status, Iberian populations continue to display relatively high levels of heterozygosity and allelic richness, similar to those found in larger Scottish populations. Furthermore, in the R. Asón no evidence was found for a historical loss of genetic diversity despite a marked decline in abundance during the last five decades. Thus, our results point to two familiar paradigms in salmonid conservation: (1)␣endangered populations can maintain relatively high levels of genetic variation despite their small size, and (2) marked population declines may not necessarily result in a significant loss of genetic diversity. Although there are several explanations for such results, microsatellite data and physical tagging suggest that high levels of dispersal and asymmetric gene flow have probably helped to maintain genetic diversity in these peripheral populations, and thus to avoid the negative consequences of inbreeding.
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Heredity, 2002
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