We studied the salmonid fish Arctic charr, Salvelinus alpinus, in a small and shallow landlocked ... more We studied the salmonid fish Arctic charr, Salvelinus alpinus, in a small and shallow landlocked lake in NW Iceland. The lake is productive but the only fish present is Arctic charr. Despite the apparent absence of discrete benthic and limnetic habitats for fish, two forms of Arctic charr are found in the lake. They show subtle differences in morphology related to swimming performance and manoeuvrability, but differences in life history such as growth, and age and size at sexual maturation are more pronounced. Both forms have benthic feeding habits with one form consuming greater number of species than the other. We suggest that the segregation of these forms is based on the evolution of a specialist from a local generalist and that this has been made possible by the absence of a common fish competitor in similar lakes, the threespined stickleback Gasterosteous muleatus.
This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Biological Journal of The Linnean Society, Jun 1, 2002
Icelandic threespine sticklebacks show parallel sympatric morphological differences related to di... more Icelandic threespine sticklebacks show parallel sympatric morphological differences related to different substrate habitats in four Icelandic lakes. The level of morphological diversification varies among the lakes, ranging from a population with a wide morphological distribution to a population with clear resource morphs, where morphological diversification was reflected in diet differences. These differences in morphological divergence are closely related to the differences in the ecological surroundings of each population. This appears to be resource polymorphism, which may lead to population differentiation and speciation. Trophically related sexual dimorphism was also common in these sticklebacks, which is possibly the result of sexual selection or habitat segregation by the sexes.
Er syndin náttúruleg? Um mikilvaegi heimsmynda og uppsprettu gilda Inngangur Vistkerfi jarðar haf... more Er syndin náttúruleg? Um mikilvaegi heimsmynda og uppsprettu gilda Inngangur Vistkerfi jarðar hafa allt frá upphafi tekið stöðugum breytingum sem einkennist ekki síst af þróun lífveranna. Náttúran er ekki kyrrstaeð. Lífið á jörðinni hefur í gegnum aldirnar staðið frammi fyrir ýmsum ógnum, svo sem eldgosum, ísöldum og fallandi loftsteinum. Samhliða haegfara breytingum hafa miklar og afdrifaríkar sviptingar eða hamfarir átt sér stað. Við lifum slíka tíma. Það sem er öðruvísi núna, er að ógnin á sér raetur í hegðun mannanna, sem hafa með drottnunarhlutverki sínu, taeknigetu og framkvaemdasemi haft þau áhrif að vistkerfi jarðar eru að umbyltast; lífríkinu hnignar og búsvaeði þverra. Þjóðir heims keppast við að ná tökum á loftslagsbreytingum af völdum stjórnlausrar kolefnislosunar okkar síðustu 300 árin. 1 Í ár er jafnframt tekist á við endurskoðun áaetlana um viðhald og endurheimt líffraeðilegrar fjölbreytni, sem hefur snarminnkað á undanförnum áratugum, en framkvaemd fyrri áaetlana hefur að mestu mistekist. 2 Eins og Andri Snaer Magnason rithöfundur útskýrir vel í bók sinni Um tímann og vatnið, erum við að upplifa á eigin aevi, og kynslóðanna sem við umgöngumst, breytingar á vistkerfum og lífsskilyrðum sem flestir sjá fyrir sér sem haega jarðsögulega ferla. 3 Auk þess hafa vísindamenn faert sannfaerandi rök 1 Sjá meðal annars vefsíðu Sameinuðu þjóðanna um loftslagsbreytingar: https://unfccc. int/, og upplýsingar um Loftslagsráð íslenskra stjórnvalda: https://loftslagsrad.is/.
Eins og kunnugt er blasir við okkur alvarlegur umhverfisvandi sem ógnar lífi á jörðinni. Framferð... more Eins og kunnugt er blasir við okkur alvarlegur umhverfisvandi sem ógnar lífi á jörðinni. Framferði mannsins á þar stærstan hlut að máli. Á líkingamáli má segja að orðið hafi misgengi milli viðhorfa okkar, siðferðis og lífshátta annars vegar og náttúrunnar hins vegar. Maðurinn hefur í krafti hraðvaxandi tæknilegrar getu sinnar og valds sagt sig úr lögum við vistkerfi jarðarinnar og farið að drottna yfir því og nýta sér á mjög óvarlegan hátt. Með því vinnur hann gegn viðgangi náttúrunnar sem hann er þó órjúfanlega samofinn. Í þessu birtist áðurnefnt misgengi. Í ritgerð þessari er leitast við að greina og leita skilnings á þessari stöðu, orsökum hennar og afleiðingum sem og úrræðum við vandanum. Nálgunin er þverfagleg og niðurstöður vísinda og fræða eru skoðaðar samhliða áhrifum siðmenningar og gildismats. Í þessu skyni er stuðst við leiðir líffræði og heimspeki, ekki síst líftáknfræði og siðfræði, og bent á órofa samspil þessara greina. Niðurstaðan er sú að menningu okkar, þekkingu og...
Er syndin náttúruleg? Um mikilvaegi heimsmynda og uppsprettu gilda Inngangur Vistkerfi jarðar haf... more Er syndin náttúruleg? Um mikilvaegi heimsmynda og uppsprettu gilda Inngangur Vistkerfi jarðar hafa allt frá upphafi tekið stöðugum breytingum sem einkennist ekki síst af þróun lífveranna. Náttúran er ekki kyrrstaeð. Lífið á jörðinni hefur í gegnum aldirnar staðið frammi fyrir ýmsum ógnum, svo sem eldgosum, ísöldum og fallandi loftsteinum. Samhliða haegfara breytingum hafa miklar og afdrifaríkar sviptingar eða hamfarir átt sér stað. Við lifum slíka tíma. Það sem er öðruvísi núna, er að ógnin á sér raetur í hegðun mannanna, sem hafa með drottnunarhlutverki sínu, taeknigetu og framkvaemdasemi haft þau áhrif að vistkerfi jarðar eru að umbyltast; lífríkinu hnignar og búsvaeði þverra. Þjóðir heims keppast við að ná tökum á loftslagsbreytingum af völdum stjórnlausrar kolefnislosunar okkar síðustu 300 árin. 1 Í ár er jafnframt tekist á við endurskoðun áaetlana um viðhald og endurheimt líffraeðilegrar fjölbreytni, sem hefur snarminnkað á undanförnum áratugum, en framkvaemd fyrri áaetlana hefur að mestu mistekist. 2 Eins og Andri Snaer Magnason rithöfundur útskýrir vel í bók sinni Um tímann og vatnið, erum við að upplifa á eigin aevi, og kynslóðanna sem við umgöngumst, breytingar á vistkerfum og lífsskilyrðum sem flestir sjá fyrir sér sem haega jarðsögulega ferla. 3 Auk þess hafa vísindamenn faert sannfaerandi rök 1 Sjá meðal annars vefsíðu Sameinuðu þjóðanna um loftslagsbreytingar: https://unfccc. int/, og upplýsingar um Loftslagsráð íslenskra stjórnvalda: https://loftslagsrad.is/.
Temperature and individual egg size have been long studied in the development of fishes because o... more Temperature and individual egg size have been long studied in the development of fishes because of their direct effects on individual fitness. Here we studied the combined effects of three important factors for fish development, i.e. egg size, social environment and water temperature. Arctic charr (Salvelinus alpinus), a coldwater fish known to be phenotypically plastic, was used to investigate how these factors may affect growth and foraging behaviour of juvenile fish in a benign environment. We accounted for the social environment during early development by comparing fish raised in groups and in isolation. We examined the effect of egg size and a 2˚C difference on foraging behaviour, activity and growth a few weeks after first feeding. Growth trajectories of fish originating from large and small eggs were similar within each temperature: larger fish coming large eggs were at all time larger than smaller fish. There was no indication that small fish raised at a higher temperature grew faster than larger fish raised at a lower temperature. A 2˚C difference in temperature affected the behaviour of fish differently according to body size and/or social context. The foraging probability difference between fish raised in groups and fish briefly isolated was higher at 4.5˚C than at 6.5˚C for both size fish. Finally, there was no repeatability in foraging behaviour and mobility for isolated individuals. These results highlight the importance of small changes in temperature when evaluating growth and behaviour of fishes, and reveal the importance of considering the interaction of temperature with other factors, e.g. individual size and social environment, especially at early stages of development in fishes. We discuss these findings in the context of rapid changes in temperature and how temperature and its interaction with other factors may affect the phenotypes, ecology and evolution of coldwater fishes.
Current data on the Y-specific sex-determining region of salmonid fishes from genera Salvelinus ,... more Current data on the Y-specific sex-determining region of salmonid fishes from genera Salvelinus , Salmo , and Oncorhynchus indicate variable polymorphisms in the homologous chromosomal locations of the sex-specific determining region. In the majority of the Atlantic lineage Arctic charr, including populations from the Fraser River, in Labrador Canada, as well as Swedish and Norwegian strains, the sex-determining locus maps to linkage group AC-4. Previously, sex-linked polymorphisms (i.e., variation in the associated sex-linked markers on AC-4) have been described in Arctic charr. Here, we report further evidence for intraspecific sex linkage group polymorphisms in Arctic charr (i.e., the detection of the SEX locus on either the AC-1 or AC-21 linkage group) and a possible conservation of a sex linkage arrangement in Icelandic Arctic charr and Atlantic salmon, involving sex-linked markers on the AC-1/21 homeologs and the European AS-1/6 homeologous linkage groups in Atlantic salmon. The evolutionary origins for the multiple sex-determining regions within the salmonid family are discussed. We also relate the variable sex-determining regions in salmonids to their ancestral proto-teleost karyotypic origins and compare these findings with what has been observed in other teleost species in general.
In 1987, a fjord in the Snaefellsnes peninsula, northwest Iceland, was dammed and a freshwater la... more In 1987, a fjord in the Snaefellsnes peninsula, northwest Iceland, was dammed and a freshwater lagoon formed. There is a large population of threespine stickleback in this lagoon. We compared morphological features of stickleback in the lagoon population to those of their marine ancestor, and morphological polymorphism within the lagoon in relation to mud and lava substrates. The freshwater stickleback have shorter spines and fewer armour plates than marine stickleback. There is also some morphological divergence between stickleback from the two substrates within the lagoon. Our results suggest that the threespine stickleback may adapt to a novel environment more rapidly than would be predicted from conventional models of biological differentiation.
Climate change poses a substantial threat to biodiversity, as rising temperatures are altering ab... more Climate change poses a substantial threat to biodiversity, as rising temperatures are altering abiotic and biotic conditions, and, in turn, imposing novel selection pressures on organisms (Crozier & Hutchings, 2014). In light of this, there is now a pressing need to understand the capacity of populations to respond and adapt to increasing temperatures (Crozier & Hutchings, 2014). Due to their
Biological Journal of The Linnean Society, Jan 7, 2013
We evaluated hypotheses of intralacustrine diversification and plastic responses to two diet envi... more We evaluated hypotheses of intralacustrine diversification and plastic responses to two diet environments in Icelandic Arctic charr (Salvelinus alpinus). Full-sib families of progeny of wild polymorphic charr from two lakes where morphs vary in their degree of phenotypic and ecological divergence were split, with half of the offspring reared on a benthic and half on a limnetic type of diet to estimate family norms of reaction. We focused on variation in craniofacial traits because they are probably functionally related to diet and complement a previous study of body shape in these charr. A hierarchical analysis of phenotypic variation between lakes, pairs of morphs within each lake, and two families within each morph found that phenotypic variation partitioned between families relative to morphs was reduced in the more ecologically diversified population, which is consistent with adaptive diversification. The effect size of plastic responses between lake populations was similar, suggesting little difference in the degree of canalization in contrast to a previous analysis of body form plasticity. Thus, the role that plastic morphological responses play in the adaptive diversification of morphs and different lake populations of Arctic charr may depend on the trait.
Canadian Journal of Fisheries and Aquatic Sciences, Apr 1, 2000
Most salmonids, as well as many other freshwater fish species in the Northern Hemisphere, have be... more Most salmonids, as well as many other freshwater fish species in the Northern Hemisphere, have been reported to show some form of daytime sheltering behaviour over the winter. Previous work has shown that temperatures around 6-8°C trigger the onset of this sheltering behaviour. However, fish from colder environments would be expected to respond differently to temperature than fish from warmer environments. The incidence of sheltering at different temperatures between two Icelandic populations of both juvenile Atlantic salmon (Salmo salar) and juvenile Arctic char (Salvelinus alpinus) was examined by quantifying the use of refuges in identical controlled laboratory conditions. The results showed clear differences in the sheltering response between the different populations. Salmon from a warm, productive stream and riverine char emerged more by day from their shelter at low temperatures (5-8°C) than did either salmon from a cold, unproductive stream or char from a landlocked lake population. These population differences indicate local adaptations that must be kept in mind when managing fish populations; moreover, the differences do not appear to be predictable on the basis of ambient thermal regimes. Résumé : On a signalé que la plupart des salmonidés, de même que de nombreux autres poissons dulcicoles de l'hémisphère Nord, s'abritent d'une façon ou d'une autre durant le jour en hiver. Des travaux antérieurs ont montré que des températures d'environ 6-8°C déclenchent ce comportement. Cependant, on devrait s'attendre à ce que les poissons des milieux plus froids réagissent différemment aux températures que les poissons des milieux plus chauds. On a examiné le taux d'utilisation de refuges à différentes températures chez deux populations islandaises de saumons atlantiques (Salmo salar) juvéniles et deux populations islandaises d'ombles chevaliers (Salvelinus alpinus) juvéniles en quantifiant l'utilisation des refuges dans des conditions de laboratoire contrôlées et identiques. Les résultats ont montré des différences évidentes dans le taux d'utilisation des refuges entre les différentes populations. Les saumons d'un cours d'eau chaud et productif et les ombles d'un cours d'eau sont demeurés plus longtemps hors de leur refuge durant le jour à de basses températures (5-8°C) que ne l'ont fait les saumons d'un cours d'eau froid et improductif ou les ombles d'une population inféodée à des eaux lacustres. Ces différentes entre populations témoignent d'adaptations locales qui doivent être prises en compte dans la gestion des populations de poissons; de plus, ces différences ne semblent pas prévisibles à partir des régimes thermiques ambiants.
When genetic constraints restrict phenotypic evolution, diversification can be predicted to evolv... more When genetic constraints restrict phenotypic evolution, diversification can be predicted to evolve along so-called lines of least resistance. To address the importance of such constraints and their resolution, studies of parallel phenotypic divergence that differ in their age are valuable. Here we investigate the parapatric evolution of six lake and stream threespine stickleback systems from Iceland and Switzerland, ranging in age from a few decades to several millennia. Using phenotypic data, we test for parallelism in ecotypic divergence between parapatric lake and stream populations and compare the observed patterns to an ancestral-like marine population. We find strong and consistent phenotypic divergence, both among lake and stream populations and between our freshwater populations and the marine population. Interestingly, ecotypic divergence in low dimensional phenotype space (i.e. single traits) is rapid and seems to be often completed within 100 years. Yet, the dimensionality of ecotypic divergence was highest in our oldest systems and only there parallel evolution of unrelated ecotypes was strong enough to overwrite phylogenetic contingency. Moreover, the dimensionality of divergence in different systems varies between trait complexes, suggesting different constraints and evolutionary pathways to their resolution among freshwater systems.
The high commercial value from the aquaculture of salmonid fishes has prompted many studies into ... more The high commercial value from the aquaculture of salmonid fishes has prompted many studies into the genetic architecture of complex traits and the need to identify genomic regions that have repeatable associations with trait variation both within and among species. We searched for quantitative trait loci (QTL) for body weight (BW), condition factor (CF) and age of sexual maturation (MAT) in families of Arctic charr (Salvelinus alpinus) from an Icelandic breeding program. QTL with genomewide significance were detected for each trait on multiple Arctic charr (AC) linkage groups (BW: AC-4, AC-20; CF: AC-7, AC-20, AC-23, AC-36; MAT: AC-13/34, AC-39). In addition to the genome-wide significant QTL for both BW and CF on AC-20, linkage groups AC-4, AC-7, AC-8, and AC-16 contain QTL for both BW and CF with chromosome-wide significance. These regions had effects (albeit weaker) on MAT with the exception of the region on AC-8. Comparisons with a North American cultured strain of Arctic charr, as well as North American populations of Atlantic salmon (Salmo salar), and rainbow trout (Oncorhynchus mykiss), reveal some conservation in QTL location and structure, particularly with respect to the joint associations of QTL influencing BW and CF. The detection of some differences in genetic architecture between the two aquaculture strains of Arctic charr may be reflective of the differential evolutionary histories experienced by these fishes, and illustrates the importance of including different strains to investigate genetic variation in a species where the intent is to use that variation in selective breeding programs. Keywords Linkage map Á Genetic map Á Salmonid Á QTL Á Comparative analysis Communicated by S. Hohmann.
doi: bioRxiv preprint 4. In sum, our study suggests that fish may diverge toward a lower standard... more doi: bioRxiv preprint 4. In sum, our study suggests that fish may diverge toward a lower standard metabolic rate in a warming world, but this might depend on connectivity and gene flow between different thermal habitats. .
Threespine stickleback most often have 10 pectoral fin rays, and it seems to be a highly canalize... more Threespine stickleback most often have 10 pectoral fin rays, and it seems to be a highly canalized trait. We observed an unusually high frequency of stickleback with 11 pectoral fin rays in a population recently isolated from the marine environment in a freshwater lagoon in Iceland. These new morphologies may be beneficial for the fish in the new habitat but may disappear because of strong canalizing selection for the typical 10 pectoral fin rays.
We studied the salmonid fish Arctic charr, Salvelinus alpinus, in a small and shallow landlocked ... more We studied the salmonid fish Arctic charr, Salvelinus alpinus, in a small and shallow landlocked lake in NW Iceland. The lake is productive but the only fish present is Arctic charr. Despite the apparent absence of discrete benthic and limnetic habitats for fish, two forms of Arctic charr are found in the lake. They show subtle differences in morphology related to swimming performance and manoeuvrability, but differences in life history such as growth, and age and size at sexual maturation are more pronounced. Both forms have benthic feeding habits with one form consuming greater number of species than the other. We suggest that the segregation of these forms is based on the evolution of a specialist from a local generalist and that this has been made possible by the absence of a common fish competitor in similar lakes, the threespined stickleback Gasterosteous muleatus.
This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Biological Journal of The Linnean Society, Jun 1, 2002
Icelandic threespine sticklebacks show parallel sympatric morphological differences related to di... more Icelandic threespine sticklebacks show parallel sympatric morphological differences related to different substrate habitats in four Icelandic lakes. The level of morphological diversification varies among the lakes, ranging from a population with a wide morphological distribution to a population with clear resource morphs, where morphological diversification was reflected in diet differences. These differences in morphological divergence are closely related to the differences in the ecological surroundings of each population. This appears to be resource polymorphism, which may lead to population differentiation and speciation. Trophically related sexual dimorphism was also common in these sticklebacks, which is possibly the result of sexual selection or habitat segregation by the sexes.
Er syndin náttúruleg? Um mikilvaegi heimsmynda og uppsprettu gilda Inngangur Vistkerfi jarðar haf... more Er syndin náttúruleg? Um mikilvaegi heimsmynda og uppsprettu gilda Inngangur Vistkerfi jarðar hafa allt frá upphafi tekið stöðugum breytingum sem einkennist ekki síst af þróun lífveranna. Náttúran er ekki kyrrstaeð. Lífið á jörðinni hefur í gegnum aldirnar staðið frammi fyrir ýmsum ógnum, svo sem eldgosum, ísöldum og fallandi loftsteinum. Samhliða haegfara breytingum hafa miklar og afdrifaríkar sviptingar eða hamfarir átt sér stað. Við lifum slíka tíma. Það sem er öðruvísi núna, er að ógnin á sér raetur í hegðun mannanna, sem hafa með drottnunarhlutverki sínu, taeknigetu og framkvaemdasemi haft þau áhrif að vistkerfi jarðar eru að umbyltast; lífríkinu hnignar og búsvaeði þverra. Þjóðir heims keppast við að ná tökum á loftslagsbreytingum af völdum stjórnlausrar kolefnislosunar okkar síðustu 300 árin. 1 Í ár er jafnframt tekist á við endurskoðun áaetlana um viðhald og endurheimt líffraeðilegrar fjölbreytni, sem hefur snarminnkað á undanförnum áratugum, en framkvaemd fyrri áaetlana hefur að mestu mistekist. 2 Eins og Andri Snaer Magnason rithöfundur útskýrir vel í bók sinni Um tímann og vatnið, erum við að upplifa á eigin aevi, og kynslóðanna sem við umgöngumst, breytingar á vistkerfum og lífsskilyrðum sem flestir sjá fyrir sér sem haega jarðsögulega ferla. 3 Auk þess hafa vísindamenn faert sannfaerandi rök 1 Sjá meðal annars vefsíðu Sameinuðu þjóðanna um loftslagsbreytingar: https://unfccc. int/, og upplýsingar um Loftslagsráð íslenskra stjórnvalda: https://loftslagsrad.is/.
Eins og kunnugt er blasir við okkur alvarlegur umhverfisvandi sem ógnar lífi á jörðinni. Framferð... more Eins og kunnugt er blasir við okkur alvarlegur umhverfisvandi sem ógnar lífi á jörðinni. Framferði mannsins á þar stærstan hlut að máli. Á líkingamáli má segja að orðið hafi misgengi milli viðhorfa okkar, siðferðis og lífshátta annars vegar og náttúrunnar hins vegar. Maðurinn hefur í krafti hraðvaxandi tæknilegrar getu sinnar og valds sagt sig úr lögum við vistkerfi jarðarinnar og farið að drottna yfir því og nýta sér á mjög óvarlegan hátt. Með því vinnur hann gegn viðgangi náttúrunnar sem hann er þó órjúfanlega samofinn. Í þessu birtist áðurnefnt misgengi. Í ritgerð þessari er leitast við að greina og leita skilnings á þessari stöðu, orsökum hennar og afleiðingum sem og úrræðum við vandanum. Nálgunin er þverfagleg og niðurstöður vísinda og fræða eru skoðaðar samhliða áhrifum siðmenningar og gildismats. Í þessu skyni er stuðst við leiðir líffræði og heimspeki, ekki síst líftáknfræði og siðfræði, og bent á órofa samspil þessara greina. Niðurstaðan er sú að menningu okkar, þekkingu og...
Er syndin náttúruleg? Um mikilvaegi heimsmynda og uppsprettu gilda Inngangur Vistkerfi jarðar haf... more Er syndin náttúruleg? Um mikilvaegi heimsmynda og uppsprettu gilda Inngangur Vistkerfi jarðar hafa allt frá upphafi tekið stöðugum breytingum sem einkennist ekki síst af þróun lífveranna. Náttúran er ekki kyrrstaeð. Lífið á jörðinni hefur í gegnum aldirnar staðið frammi fyrir ýmsum ógnum, svo sem eldgosum, ísöldum og fallandi loftsteinum. Samhliða haegfara breytingum hafa miklar og afdrifaríkar sviptingar eða hamfarir átt sér stað. Við lifum slíka tíma. Það sem er öðruvísi núna, er að ógnin á sér raetur í hegðun mannanna, sem hafa með drottnunarhlutverki sínu, taeknigetu og framkvaemdasemi haft þau áhrif að vistkerfi jarðar eru að umbyltast; lífríkinu hnignar og búsvaeði þverra. Þjóðir heims keppast við að ná tökum á loftslagsbreytingum af völdum stjórnlausrar kolefnislosunar okkar síðustu 300 árin. 1 Í ár er jafnframt tekist á við endurskoðun áaetlana um viðhald og endurheimt líffraeðilegrar fjölbreytni, sem hefur snarminnkað á undanförnum áratugum, en framkvaemd fyrri áaetlana hefur að mestu mistekist. 2 Eins og Andri Snaer Magnason rithöfundur útskýrir vel í bók sinni Um tímann og vatnið, erum við að upplifa á eigin aevi, og kynslóðanna sem við umgöngumst, breytingar á vistkerfum og lífsskilyrðum sem flestir sjá fyrir sér sem haega jarðsögulega ferla. 3 Auk þess hafa vísindamenn faert sannfaerandi rök 1 Sjá meðal annars vefsíðu Sameinuðu þjóðanna um loftslagsbreytingar: https://unfccc. int/, og upplýsingar um Loftslagsráð íslenskra stjórnvalda: https://loftslagsrad.is/.
Temperature and individual egg size have been long studied in the development of fishes because o... more Temperature and individual egg size have been long studied in the development of fishes because of their direct effects on individual fitness. Here we studied the combined effects of three important factors for fish development, i.e. egg size, social environment and water temperature. Arctic charr (Salvelinus alpinus), a coldwater fish known to be phenotypically plastic, was used to investigate how these factors may affect growth and foraging behaviour of juvenile fish in a benign environment. We accounted for the social environment during early development by comparing fish raised in groups and in isolation. We examined the effect of egg size and a 2˚C difference on foraging behaviour, activity and growth a few weeks after first feeding. Growth trajectories of fish originating from large and small eggs were similar within each temperature: larger fish coming large eggs were at all time larger than smaller fish. There was no indication that small fish raised at a higher temperature grew faster than larger fish raised at a lower temperature. A 2˚C difference in temperature affected the behaviour of fish differently according to body size and/or social context. The foraging probability difference between fish raised in groups and fish briefly isolated was higher at 4.5˚C than at 6.5˚C for both size fish. Finally, there was no repeatability in foraging behaviour and mobility for isolated individuals. These results highlight the importance of small changes in temperature when evaluating growth and behaviour of fishes, and reveal the importance of considering the interaction of temperature with other factors, e.g. individual size and social environment, especially at early stages of development in fishes. We discuss these findings in the context of rapid changes in temperature and how temperature and its interaction with other factors may affect the phenotypes, ecology and evolution of coldwater fishes.
Current data on the Y-specific sex-determining region of salmonid fishes from genera Salvelinus ,... more Current data on the Y-specific sex-determining region of salmonid fishes from genera Salvelinus , Salmo , and Oncorhynchus indicate variable polymorphisms in the homologous chromosomal locations of the sex-specific determining region. In the majority of the Atlantic lineage Arctic charr, including populations from the Fraser River, in Labrador Canada, as well as Swedish and Norwegian strains, the sex-determining locus maps to linkage group AC-4. Previously, sex-linked polymorphisms (i.e., variation in the associated sex-linked markers on AC-4) have been described in Arctic charr. Here, we report further evidence for intraspecific sex linkage group polymorphisms in Arctic charr (i.e., the detection of the SEX locus on either the AC-1 or AC-21 linkage group) and a possible conservation of a sex linkage arrangement in Icelandic Arctic charr and Atlantic salmon, involving sex-linked markers on the AC-1/21 homeologs and the European AS-1/6 homeologous linkage groups in Atlantic salmon. The evolutionary origins for the multiple sex-determining regions within the salmonid family are discussed. We also relate the variable sex-determining regions in salmonids to their ancestral proto-teleost karyotypic origins and compare these findings with what has been observed in other teleost species in general.
In 1987, a fjord in the Snaefellsnes peninsula, northwest Iceland, was dammed and a freshwater la... more In 1987, a fjord in the Snaefellsnes peninsula, northwest Iceland, was dammed and a freshwater lagoon formed. There is a large population of threespine stickleback in this lagoon. We compared morphological features of stickleback in the lagoon population to those of their marine ancestor, and morphological polymorphism within the lagoon in relation to mud and lava substrates. The freshwater stickleback have shorter spines and fewer armour plates than marine stickleback. There is also some morphological divergence between stickleback from the two substrates within the lagoon. Our results suggest that the threespine stickleback may adapt to a novel environment more rapidly than would be predicted from conventional models of biological differentiation.
Climate change poses a substantial threat to biodiversity, as rising temperatures are altering ab... more Climate change poses a substantial threat to biodiversity, as rising temperatures are altering abiotic and biotic conditions, and, in turn, imposing novel selection pressures on organisms (Crozier & Hutchings, 2014). In light of this, there is now a pressing need to understand the capacity of populations to respond and adapt to increasing temperatures (Crozier & Hutchings, 2014). Due to their
Biological Journal of The Linnean Society, Jan 7, 2013
We evaluated hypotheses of intralacustrine diversification and plastic responses to two diet envi... more We evaluated hypotheses of intralacustrine diversification and plastic responses to two diet environments in Icelandic Arctic charr (Salvelinus alpinus). Full-sib families of progeny of wild polymorphic charr from two lakes where morphs vary in their degree of phenotypic and ecological divergence were split, with half of the offspring reared on a benthic and half on a limnetic type of diet to estimate family norms of reaction. We focused on variation in craniofacial traits because they are probably functionally related to diet and complement a previous study of body shape in these charr. A hierarchical analysis of phenotypic variation between lakes, pairs of morphs within each lake, and two families within each morph found that phenotypic variation partitioned between families relative to morphs was reduced in the more ecologically diversified population, which is consistent with adaptive diversification. The effect size of plastic responses between lake populations was similar, suggesting little difference in the degree of canalization in contrast to a previous analysis of body form plasticity. Thus, the role that plastic morphological responses play in the adaptive diversification of morphs and different lake populations of Arctic charr may depend on the trait.
Canadian Journal of Fisheries and Aquatic Sciences, Apr 1, 2000
Most salmonids, as well as many other freshwater fish species in the Northern Hemisphere, have be... more Most salmonids, as well as many other freshwater fish species in the Northern Hemisphere, have been reported to show some form of daytime sheltering behaviour over the winter. Previous work has shown that temperatures around 6-8°C trigger the onset of this sheltering behaviour. However, fish from colder environments would be expected to respond differently to temperature than fish from warmer environments. The incidence of sheltering at different temperatures between two Icelandic populations of both juvenile Atlantic salmon (Salmo salar) and juvenile Arctic char (Salvelinus alpinus) was examined by quantifying the use of refuges in identical controlled laboratory conditions. The results showed clear differences in the sheltering response between the different populations. Salmon from a warm, productive stream and riverine char emerged more by day from their shelter at low temperatures (5-8°C) than did either salmon from a cold, unproductive stream or char from a landlocked lake population. These population differences indicate local adaptations that must be kept in mind when managing fish populations; moreover, the differences do not appear to be predictable on the basis of ambient thermal regimes. Résumé : On a signalé que la plupart des salmonidés, de même que de nombreux autres poissons dulcicoles de l'hémisphère Nord, s'abritent d'une façon ou d'une autre durant le jour en hiver. Des travaux antérieurs ont montré que des températures d'environ 6-8°C déclenchent ce comportement. Cependant, on devrait s'attendre à ce que les poissons des milieux plus froids réagissent différemment aux températures que les poissons des milieux plus chauds. On a examiné le taux d'utilisation de refuges à différentes températures chez deux populations islandaises de saumons atlantiques (Salmo salar) juvéniles et deux populations islandaises d'ombles chevaliers (Salvelinus alpinus) juvéniles en quantifiant l'utilisation des refuges dans des conditions de laboratoire contrôlées et identiques. Les résultats ont montré des différences évidentes dans le taux d'utilisation des refuges entre les différentes populations. Les saumons d'un cours d'eau chaud et productif et les ombles d'un cours d'eau sont demeurés plus longtemps hors de leur refuge durant le jour à de basses températures (5-8°C) que ne l'ont fait les saumons d'un cours d'eau froid et improductif ou les ombles d'une population inféodée à des eaux lacustres. Ces différentes entre populations témoignent d'adaptations locales qui doivent être prises en compte dans la gestion des populations de poissons; de plus, ces différences ne semblent pas prévisibles à partir des régimes thermiques ambiants.
When genetic constraints restrict phenotypic evolution, diversification can be predicted to evolv... more When genetic constraints restrict phenotypic evolution, diversification can be predicted to evolve along so-called lines of least resistance. To address the importance of such constraints and their resolution, studies of parallel phenotypic divergence that differ in their age are valuable. Here we investigate the parapatric evolution of six lake and stream threespine stickleback systems from Iceland and Switzerland, ranging in age from a few decades to several millennia. Using phenotypic data, we test for parallelism in ecotypic divergence between parapatric lake and stream populations and compare the observed patterns to an ancestral-like marine population. We find strong and consistent phenotypic divergence, both among lake and stream populations and between our freshwater populations and the marine population. Interestingly, ecotypic divergence in low dimensional phenotype space (i.e. single traits) is rapid and seems to be often completed within 100 years. Yet, the dimensionality of ecotypic divergence was highest in our oldest systems and only there parallel evolution of unrelated ecotypes was strong enough to overwrite phylogenetic contingency. Moreover, the dimensionality of divergence in different systems varies between trait complexes, suggesting different constraints and evolutionary pathways to their resolution among freshwater systems.
The high commercial value from the aquaculture of salmonid fishes has prompted many studies into ... more The high commercial value from the aquaculture of salmonid fishes has prompted many studies into the genetic architecture of complex traits and the need to identify genomic regions that have repeatable associations with trait variation both within and among species. We searched for quantitative trait loci (QTL) for body weight (BW), condition factor (CF) and age of sexual maturation (MAT) in families of Arctic charr (Salvelinus alpinus) from an Icelandic breeding program. QTL with genomewide significance were detected for each trait on multiple Arctic charr (AC) linkage groups (BW: AC-4, AC-20; CF: AC-7, AC-20, AC-23, AC-36; MAT: AC-13/34, AC-39). In addition to the genome-wide significant QTL for both BW and CF on AC-20, linkage groups AC-4, AC-7, AC-8, and AC-16 contain QTL for both BW and CF with chromosome-wide significance. These regions had effects (albeit weaker) on MAT with the exception of the region on AC-8. Comparisons with a North American cultured strain of Arctic charr, as well as North American populations of Atlantic salmon (Salmo salar), and rainbow trout (Oncorhynchus mykiss), reveal some conservation in QTL location and structure, particularly with respect to the joint associations of QTL influencing BW and CF. The detection of some differences in genetic architecture between the two aquaculture strains of Arctic charr may be reflective of the differential evolutionary histories experienced by these fishes, and illustrates the importance of including different strains to investigate genetic variation in a species where the intent is to use that variation in selective breeding programs. Keywords Linkage map Á Genetic map Á Salmonid Á QTL Á Comparative analysis Communicated by S. Hohmann.
doi: bioRxiv preprint 4. In sum, our study suggests that fish may diverge toward a lower standard... more doi: bioRxiv preprint 4. In sum, our study suggests that fish may diverge toward a lower standard metabolic rate in a warming world, but this might depend on connectivity and gene flow between different thermal habitats. .
Threespine stickleback most often have 10 pectoral fin rays, and it seems to be a highly canalize... more Threespine stickleback most often have 10 pectoral fin rays, and it seems to be a highly canalized trait. We observed an unusually high frequency of stickleback with 11 pectoral fin rays in a population recently isolated from the marine environment in a freshwater lagoon in Iceland. These new morphologies may be beneficial for the fish in the new habitat but may disappear because of strong canalizing selection for the typical 10 pectoral fin rays.
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