Michael Hansen's Publications List

Mitogenome sequencing reveals shallow evolutionary histories and recent divergence time between morphologically and ecologically distinct European whitefish (Coregonus spp.)

2012-01-28T18:16:40Z

M W Jacobsen, M M Hansen, L Orlando, D Bekkevold, L Bernatchez, E Willerslev, M T P Gilbert (2012) Molecular Ecology 21: in press

Monitoring adaptive genetic responses to environmental change

2011-12-18T17:02:32Z

MM Hansen, I Olivieri, DM Waller, EE Nielsen, the Genetic Monitoring Group (2012) Molecular Ecology 21: In press

The effect of spatially varying selection on locally adaptive alleles in the panmictic American eel (Anguilla rostrata)

2011-12-18T17:06:01Z

P-A Gagnaire, E Normandeau, C Côté, MM Hansen, L Bernatchez (2012) Genetics : In press

Differences in salinity tolerance and gene expression between two populations of Atlantic cod (Gadus morhua) in response to salinity stress

2012-01-02T19:56:15Z

P F Larsen, E E Nielsen, K Meier, P A Olsvik, M M Hansen, V Loeschcke (2012) Biochemical Genetics 50: in press

An assessment of the spatial scale of local adaptation in brown trout (Salmo trutta L.): footprints of selection at microsatellite DNA loci

2011-12-18T16:56:34Z

Meier, K., Hansen, M.M., Bekkevold, D., Skaala, Ø., Mensberg, K.-L.D. (2011) Heredity 106: 488-499

Extent and scale of local adaptation in salmonid fishes: review and meta-analysis

2011-12-18T16:55:25Z

Fraser, D.J., Weir, L.K., Bernatchez, L., Hansen, M.M., Taylor, E.B. (2011) Heredity 106: 404-420

All roads lead to home: Panmixia of European eel in the Sargasso Sea

2011-12-18T16:57:31Z

Als, T.D., Hansen, M.M., Maes, G.E., Castonguay, M., Riemann, L., Aarestrup, K., Munk, P., Sparholt, H., Hanel, R., Bernatchez, L. (2011) Molecular Ecology 20: 1333-1346

Differential timing of gene expression regulation between leptocephali of the two Anguilla eel species in the Sargasso Sea.

2012-01-02T19:53:10Z

L Bernatchez, J St-Cyr, E Normandeau, GE Maes, TD Als, S Kalujnaia, G Cramb, M Castonguay, MM Hansen (2011) Ecology and Evolution 1: 459-467

A comparison of SNP and STR loci for delineating population structure and performing individual genetic assignment

2010-01-06T10:46:53Z

K A Glover, M M Hansen, S Lien, T D Als, B Høyheim & Ø Skaala (2010) BMC Genetics 11: 2

Neglect of genetic diversity in implementation of the Convention on Biological Diversity.

2010-02-22T19:31:56Z

L Laikre, F W Allendorf, L C Aroner, C Scott Baker, D P Gregovich, M M Hansen, J A Jackson, K C Kendall, K McKelvey, M C Neel, I Olivieri, N Ryman, M K Schwartz, R Shortbull, J B Stetz, D A Tallmon, B L Taylor, C D Vojta, D M Waller, R S Waples (2010) Conservation Biology 24: 84-86

Population and family structure of brown trout, Salmo trutta, in a Mediterranean stream

2010-11-21T21:03:19Z

M Vera, N Sanz, M M Hansen, A Almodovar, J L Garcia-Marin (2010) Marine and Freshwater Research 61: 672-681

Expression of interest: transcriptomics and the designation of conservation units

2010-04-16T19:50:17Z

M M Hansen (2010) Molecular Ecology 19: 1757-1759

Sequencing, de novo annotation and analysis of the first Anguilla anguilla transcriptome: EeelBase opens new perspectives for the study of the critically endangered European eel

2010-11-21T21:06:35Z

Coppe, A., Pujolar, J.M., Maes, G.E., Larsen, P.F., Hansen, M.M., Bernatchez, L., Zane, L., Bortoluzzi, S. (2010) BMC Genetics 11: 635

Qualitative assessment of the diet of European eel larvae in the Sargasso Sea resolved by DNA barcoding

2010-11-21T21:04:42Z

European eels (Anguilla anguilla) undertake spawning migrations of more than 5000 kilometres from continental Europe and North Africa to frontal zones in the Sargasso Sea. Subsequently, the larval offspring are advected by large-scale eastward ocean currents towards continental waters. However, the Sargasso Sea is oligotrophic, with generally low plankton biomass, and the feeding biology of eel la...

L Riemann, H Alfredsson, M M Hansen, T D Als, T G Nielsen, P Munk, K Aarestrup, G E Maes, H Sparholt, M I Pedersen, M Bachler, M Castonguay (2010) Biology Letters 6: 819-822

Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels

2010-11-21T21:02:27Z

Anguillid freshwater eels show remarkable life histories. In the Atlantic, the European eel (Anguilla anguilla) and American eel (A. rostrata) undertake extensive migrations to spawn in the oceanic Sargasso Sea, and subsequently the offspring drift to foraging areas in Europe and North America, first as leaf-like leptocephali larvae which later metamorphose into glass eels. Since recruitment of Eu...

P Munk, M M Hansen, G E Maes, T G Nielsen, M Castonguay, L Riemann, H Sparholt, T D Als, K Aarestrup, N G Andersen, M Bachler (2010) Proceedings of the Royal Society London, Series B: Biological Sciences 277: 3593-3599

Identifying footprints of selection in stocked brown trout populations: a spatio-temporal approach.

2010-04-16T19:51:38Z

Studies of interactions between farmed and wild salmonid fishes have suggested reduced fitness of farmed strains in the wild, but evidence for selection at the genic level is lacking. We studied three brown trout populations in Denmark which have been significantly admixed with stocked hatchery trout (19 to 64%), along with two hatchery strains used for stocking. The wild populations were represen...

M M Hansen, K Meier, K-L D Mensberg (2010) Molecular Ecology 19: 1787-1800

Identifying the source of farmed escaped Atlantic salmon (Salmo salar): Bayesian clustering analysis increases accuracy of assignment

2009-04-25T15:59:46Z

Farmed Atlantic salmon escapees represent a significant threat to the genetic integrity of natural populations. Not all escapement events are reported, and consequently, there is a need to develop an effective tool for the identification of escapees. In this study, >2200 salmon were collected from 44 cages located on 26 farms in the Hardangerfjord, western Norway. This fjord represents one of the ...

K A Glover, M M Hansen, Ø Skaala (2009) Aquaculture 290: 37-46

Sixty years of anthropogenic pressure: a spatio-temporal genetic analysis of brown trout populations subject to stocking and population declines

2009-12-08T18:47:40Z

Analyses of historical samples can provide invaluable information on changes to the genetic composition of natural populations resulting from human activities. Here, we analyze 21 microsatellite loci in historical (archived scales from 1927-1956) and contemporary samples of brown trout (Salmo trutta) from six neighbouring rivers in Denmark, to compare the genetic structure of wild populations bef...

M M Hansen, D J Fraser, K R Meier, K L-D Mensberg (2009) Molecular Ecology 18: 2549-2562

Admixture analysis of stocked brown trout populations using mapped microsatellite DNA markers: indigenous trout persist in introgressed populations

2009-12-08T18:48:00Z

Admixture between wild and captive populations is an increasing concern in conservation biology. Understanding the extent of admixture and the processes involved requires identification of admixed and non-admixed individuals. This can be achieved by statistical methods employing Bayesian clustering, but resolution is low if genetic differentiation is weak. Here, we analyze stocked brown trout popu...

M M Hansen, K-L D Mensberg (2009) Biology Letters 5: 656-659

Oceanic Spawning Migration of the European Eel (Anguilla anguilla)

2009-09-26T09:46:37Z

Aarestrup, K., Økland, F., Hansen, M.M., Righton, D., Gargan, P, Castonguay, M., Bernatchez, L., Howey, P., Sparholt, H., Pedersen, M.I., & McKinley, R.S. (2009) Science 325: 1660

Depauperate genetic variability detected in the American and European bison using genomic techniques.

2009-12-08T19:29:05Z

A total of 929 polymorphic SNPs in EB (out of 54,000 SNPs screened using a BovineSNP50 Illumina Genotyping BeadChip), and 1,524 and 1,403 polymorphic SNPs in WB and PB, respectively, were analysed. EB, WB and PB have all undergone recent drastic reductions in population size. Accordingly, they exhibited extremely depauperate genomes, deviations from genetic equilibrium and a genome organization co...

C Pertoldi, M Tokarska, J Wójcik, D Demontis, V Loeschcke, V R Gregersen, D Coltman, G A Wilson, E Randi, M M Hansen, C Bendixen (2009) Biology Direct 4: 48

Spatially and temporally fluctuating selection at non-MHC immune genes: evidence from TAP polymorphism in populations of brown trout (Salmo trutta, L.).

2008-01-31T09:35:15Z

Temporal samples of Danish brown trout (Salmo trutta) from populations representing varying geographical scales were analysed using eight putatively neutral microsatellite loci and two microsatellite loci embedded in TAP genes (Transporter associated with Antigen Processing). These genes encode molecules that are central to the major histocompatibility complex (MHC) class I restricted antigen pres...

L F Jensen, M M Hansen, K-L D Mensberg, V Loeschcke (2008) Heredity 100: 79-91

Genetic structure and demographic history of brown trout (Salmo trutta) populations from the southern Balkans

2009-12-08T18:49:29Z

1. The present study was designed to characterize the genetic structure of brown trout (Salmo trutta) populations from the southern Balkans and to assess the spread of non-native strains and their introgression into native trout gene pools. We analysed polymorphism at nine microsatellite loci in seven supposedly non-admixed and three stocked brown trout populations. 2. The analyses confirmed th...

A P Apostolidis, M-J Madeira, M M Hansen, A Machordom (2008) Freshwater Biology 53: 1555-1566

Genetic and environmental correlates of morphological variation in a marine fish: the case of Baltic Sea herring

2009-12-08T18:48:34Z

Baltic Sea herring (Clupea harengus) have been shown to exhibit morphological differences across the marked salinity and temperature gradients in the region. Here we analyse genetic (nine microsatellite loci), morpho metric (skull shape), and meristic (pectoral fin rays and number of vertebrae) variations across seven samples of spawning herring collected from four spawning locations in the Baltic...

H B H Jørgensen, C Pertoldi, M M Hansen, D E Ruzzante, V Loeschcke (2008) Canadian Journal of Fisheries and Aquatic Science 65: 389-400

Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: the case of European lake whitefish and the endangered North Sea houting (Coregonus spp.)

2009-12-08T18:50:01Z

BACKGROUND: Adaptive radiation within fishes of the Coregonus lavaretus complex has created numerous morphs, posing significant challenges for taxonomy and conservation priorities. The highly endangered North Sea houting (C. oxyrhynchus; abbreviated NSH) has been considered a separate species from European lake whitefish (C. lavaretus; abbreviated ELW) due to morphological divergence and adaptat...

M M Hansen, D J Fraser, T D Als, K-L D Mensberg (2008) BMC Evolutionary Biology 8: 137

Visible implant elastomer (VIE) marking of brown trout, Salmo trutta, alevins

2009-12-08T18:49:08Z

L F Jensen, M M Hansen, S Thomassen (2008) Fisheries Management and Ecology 15: 81-83

Waking the dead: the value of population genetic analyses of historical samples.

2008-12-13T09:41:11Z

Archived scales and otoliths constitute a unique source of DNA that potentially enables extension of the temporal scale of genetic studies of fish populations by decades and even centuries. We review recent insights into fish population and conservation genetics obtained using analysis of DNA from archived samples. This involves both new knowledge about demographic parameters and population struct...

E E Nielsen & M M Hansen (2008) Fish and Fisheries 9: 450-461

Landscape genetics, historical isolation and cross-Andean gene flow in the wax palm Ceroxylon echinulatum (Arecaceae).

2009-12-08T18:50:24Z

Knowledge of the role of landscapes in shaping genetic connectivity and divergence is essential for understanding patterns of biogeography and diversity. This is particularly relevant for the Andes region, a major biodiversity hotspot of relatively recent origin. We examined the phylogeography and landscape genetics of the Andean wax palm Ceroxylon echinulatum (Arecaceae) that occurs in two narrow...

P Trénel, M M Hansen, S Normand, F Borchsenius (2008) Molecular Ecology 17: 3528-3540

Population transcriptomics of life-history variation in the genus Salmo

2009-12-08T18:50:57Z

In this study, we demonstrate the power of applying complementary DNA (cDNA) microarray technology to identifying candidate loci that exhibit subtle differences in expression levels associated with a complex trait in natural populations of a nonmodel organism. Using a highly replicated experimental design involving 180 cDNA microarray experiments, we measured gene-expression levels from 1098 trans...

T Giger, L Excoffier, U Amstutz, P J R Day, A Champigneulle, M M Hansen, J Kelso, C R Largiadèr (2008) Molecular Ecology 17: 3095-3108

Local adaptation in brown trout early life-history traits: implications for climate change adaptability.

2009-12-08T18:52:10Z

Knowledge of local adaptation and adaptive potential of natural populations is becoming increasingly relevant due to anthropogenic changes of the environment, such as climate change. The concern is that populations will be negatively affected by increasing temperatures without the capacity to adapt. Temperature-related adaptability in traits related to phenology and early life-history are expected...

L F Jensen, M M Hansen, C Pertoldi, G Holdensgaard, K-L D Mensberg, V Loeschcke (2008) Proceedings of the Royal Society London, Series B: Biological Sciences 275: 2859-2868

Gene flow, effective population size and selection at major histocompatibility complex genes: brown trout in the Hardanger Fjord, Norway.

2009-12-08T18:53:00Z

Brown trout populations in the Hardanger Fjord, Norway, have declined drastically due to increased exposure to salmon lice from salmonid aquaculture. We studied contemporary samples from seven populations and historical samples (1972 and 1983) from the two largest populations, one of which has declined drastically whereas the other remains stable. We analysed 11 microsatellite loci, including one ...

M M Hansen, Ø Skaala, L F Jensen, D Bekkevold, K-L D Mensberg (2007) Molecular Ecology 16: 1413-1425

Investigating the Genetics of Populations

2008-01-30T21:22:36Z

M M Hansen, B Villanueva, E E Nielsen, D Bekkevold (2007) The Atlantic Salmon: Genetics, Conservation and Management 86-113

Comparative estimation of effective population sizes and temporal gene flow in two contrasting population systems.

2009-12-08T18:52:32Z

Estimation of effective population sizes (N(e)) and temporal gene flow (N(e)m, m) has many implications for understanding population structure in evolutionary and conservation biology. However, comparative studies that gauge the relative performance of N(e), N(e)m or m methods are few. Using temporal genetic data from two salmonid fish population systems with disparate population structure, we (i)...

D J Fraser, M M Hansen, S Østergaard, N Tessier, M Legault, L Bernatchez (2007) Molecular Ecology 16: 3866-3889

Landscape genetics goes to sea.

2009-12-08T18:53:27Z

ABSTRACT: A recent study revealing geographical and environmental barriers to gene flow in the harbour porpoise shows the great potential of 'landscape genetics' when applied to marine organisms.

M M Hansen, J Hemmer-Hansen (2007) Journal of Biology 6: 6

Life history shapes gene expression in salmonids.

2009-12-08T18:53:50Z

T Giger, L Excoffier, P J R Day, A Champigneulle, M M Hansen, R Powell, C R Largiadèr (2006) Current Biology 16: R281-R282

Underwater but not out of sight : genetic monitoring of effective population size in the endangered North Sea houting (Coregonus oxyrhynchus)

2009-12-08T18:55:36Z

We analysed 12 microsatellite DNA loci in temporal samples (1980, 1994, and 2002) from the only remaining indigenous population of the North Sea houting (Coregonus oxyrhynchus) in the Vidaa River, Denmark. Using a novel temporal method, we estimated effective population size (N-e) to be 577.4 (90% highest posterior density limits 297.2-3719.8). The same method was used to estimate Ne at the beginn...

M M Hansen, E E Nielsen, K L D Mensberg (2006) Canadian Journal of Fisheries and Aquatic Science 63: 780-787

Loss of genetic variation in hatchery-reared Indian major carps, Catla catla.

2009-12-08T18:56:56Z

The hypothesis that effective population sizes are low in hatchery-reared catla (Catla catla) from Bangladesh, possibly leading to inbreeding and loss of variation, was tested. The study was based on analysis of seven microsatellite loci in three samples of hatchery-reared catla and four samples representing wild populations. Pair-wise estimates of genetic differentiation between samples were low ...

M M Hansen, V Simonsen, K-L D Mensberg, M R I Sarder, M S Alam (2006) Journal of Fish Biology 69 (sb): 229-241

Evidence of microsatellite hitch-hiking selection in Atlantic cod (Gadus morhua L.): implications for inferring population structure in nonmodel organisms.

2009-12-08T18:54:29Z

Microsatellites have gained wide application for elucidating population structure in nonmodel organisms. Since they are generally noncoding, neutrality is assumed but rarely tested. In Atlantic cod (Gadus morhua L.), microsatellite studies have revealed highly heterogeneous estimates of genetic differentiation among loci. In particular one locus, Gmo 132, has demonstrated elevated genetic differen...

E E Nielsen, M M Hansen, D Meldrup (2006) Molecular Ecology 15: 3219-3229

Genetic impact of gadoid culture on wild fish populations : predictions, lessons from salmonids, and possibilities for minimizing adverse effects

2009-12-08T18:54:59Z

Little is known about the effects of ranched gadoids escaping into wild populations, and plans for substantial up-scaling of gadoid mariculture raise concerns about detrimental effects on local gene pools. Genetic studies from salmonid populations subjected to intentional or unintentional releases of hatchery-produced fish suggest that wild gene pools are affected by introgression, but that the ge...

D Bekkevold, M M Hansen, E E Nielsen (2006) ICES Journal of Marine Science 63: 198-208

Genetic restoration of a stocked brown trout (Salmo trutta) population using microsatellite DNA analysis of historical and contemporary samples

2009-12-08T18:56:06Z

1. Gene flow from domesticated to wild populations is a major threat to wild salmonid fish. However, few studies have addressed how populations could be restored after admixture has occurred. We analysed the prospects for restoring the previously intensively stocked brown trout population of the Skjern River, Denmark, by identifying remaining non-admixed individuals to be used for supportive breed...

M M Hansen, D Bekkevold, L F Jensen, K-L D Mensberg, E E Nielsen (2006) Journal of Applied Ecology 43: 679-689

Spring-spawning herring (Clupea harengus L.) in the southwestern Baltic Sea : do they form genetically distinct spawning waves?

2009-12-08T18:59:49Z

Temporal sampling within the spring-spawning season has revealed differentiation in length-at-age in herring at Rugen and differentiation in, e.g., Anisakis infestation rate, otolith microstructure, and gillraker counts in Gdansk Bay, leading to the expectation that spawning waves consist of distinct herring populations. We tested this expectation by analysing genetic variation at nine microsatell...

H B H Jorgensen, M M Hansen, V Loeschcke (2005) ICES Journal of Marine Science 62: 6 1065-1075

Spatial and temporal genetic differentiation and effective population size of brown trout (Salmo trutta, L.) in small Danish rivers

2009-12-08T18:59:22Z

The spatial and temporal genetic structure of brown trout populations from three small tributaries of Lake Hald, Denmark, was studied using analysis of variation at eight microsatellite loci. From two of the populations temporal samples were available, separated by up to 13 years (3.7 generations). Significant genetic differentiation was observed among all samples, however, hierarchical analysis o...

L F Jensen, M M Hansen, J Carlsson, V Loeschcke, K L D Mensberg (2005) Conserv ation Genetics 6: 615-621

Stocking impact and temporal stability of genetic composition in a brackish northern pike population (Esox lucius L.), assessed using microsatellite DNA analysis of historical and contemporary samples.

2008-01-31T17:23:23Z

During the last decade, brackish northern pike populations in Denmark have been subject to stocking programmes, using nonindigenous pike from freshwater lakes, in order to compensate for drastic population declines. The present study was designed to investigate the genetic impact of stocking freshwater pike into a brackish pike population in Stege Nor, Denmark. We analysed polymorphism at eight mi...

P F Larsen, M M Hansen, E E Nielsen, L F Jensen, V Loeschcke (2005) Heredity 95: 136-143

Sibship within samples of brown trout (Salmo trutta) and implications for supportive breeding

2009-12-08T18:58:08Z

We analysed family relationships among brown trout from two small tributary populations that have been suggested as a source of individuals for supportive breeding, using variation at eight microsatellite loci. As a control, we analysed a sample of supposedly unrelated individuals representing a large anadromous population, and we simulated unrelated individuals based on the allelic distributions ...

M M Hansen, L F Jensen (2005) Conserv ation Genetics 6: 2 297-305

Microsatellite DNA analysis of northern pike (Esox lucius L.) populations : insights into the genetic structure and demographic history of a genetically depauperate species

2009-12-08T18:58:45Z

The northern pike Esox lucius L. is a freshwater fish exhibiting pronounced population subdivision and low genetic variability. However, there is limited knowledge on phylogeographical patterns within the species, and it is not known whether the low genetic variability reflects primarily current low effective population sizes or historical bottlenecks. We analysed six microsatellite loci in ten po...

B H Jacobsen, M M Hansen, V Loeschcke (2005) Biological Journal of the Linnean Society 84: 91-101

Widespread hybridisation among species of Indian major carps in hatcheries, but not in the wild

2009-12-08T19:01:15Z

Twenty‐one allozyme loci in samples of wild‐caught and hatchery‐reared Indian major carps from Bangladesh were analysed. Bayesian model‐based clustering analysis revealed the presence of four taxa, corresponding to the three known species along with a fourth unknown taxon present in two hatchery samples. Individual admixture coefficients showed that 24% of all hatchery‐reared fishes were...

V Simonsen, M M Hansen, K-L D Mensberg, M Alam, M Sarder (2005) Journal of Fish Biology 67: 794-808

Marine landscapes and population genetic structure of herring (Clupea harengus L.) in the Baltic Sea.

2009-12-08T18:57:36Z

Numerically small but statistically significant genetic differentiation has been found in many marine fish species despite very large census population sizes and absence of obvious barriers to migrating individuals. Analyses of morphological traits have previously identified local spawning groups of herring (Clupea harengus L.) in the environmentally heterogeneous Baltic Sea, whereas allozyme mark...

H B H Jørgensen, M M Hansen, D Bekkevold, D E Ruzzante, V Loeschcke (2005) Molecular Ecology 14: 3219-3234

Present and past microsatellite variation and assessment of genetic structure in Eurasian badger (Meles meles) in Denmark

2009-12-08T19:00:47Z

During the past 50 years the number of badgers (Meles meles) in Denmark has declined by c. 50%. To assess the genetic consequences of the demographic decline, six DNA-microsatellite loci were used to analyse 139 badger tissue-samples, which were collected in 1995-98 from three zones (1, 2 and 3) in Jutland (Denmark). Results from contemporary samples were compared to data obtained from DNA extract...

C Pertoldi, V Loeschchke, E Randi, A B Madsen, M M Hansen, R Bijlsma, L Van De Zande (2005) Journal of Zoology 265: 387-394

Genetic introgression between wild and stocked salmonids and the prospects for using molecular markers in population rehabilitation: the case of the Adriatic grayling (Thymallus thymallus L. 1785).

2008-01-31T21:06:44Z

In the north Adriatic basin, a morphologically and genetically distinct lineage of grayling is found, designated as the Adriatic grayling. In Slovenia, the Adriatic grayling is restricted to the Soca river system, where it is critically endangered. The most pertinent threat is stocking with non-native, highly divergent Sava (Danubian) drainage stock, and this activity has been going on for more th...

S Susnik, P Berrebi, P Dovc, M M Hansen, A Snoj (2004) Heredity 93: 273-282

Genetic population structure of turbot (Scophthalmus maximus L.) supports the presence of multiple hybrid zones for marine fishes in the transition zone between the Baltic Sea and the North Sea.

2009-12-08T19:03:07Z

Genetic population structure of turbot (Scophthalmus maximus L.) in the Northeast Atlantic was investigated using eight highly variable microsatellite loci. In total 706 individuals from eight locations with temporal replicates were assayed, covering an area from the French Bay of Biscay to the Aaland archipelago in the Baltic Sea. In contrast to previous genetic studies of turbot, we found signif...

E E Nielsen, P H Nielsen, D Meldrup, M M Hansen (2004) Molecular Ecology 13: 585-595

Genetic detection of sex-specific dispersal in historical and contemporary populations of anadromous brown trout Salmo trutta.

2009-12-08T19:01:46Z

The study of sex-biased dispersal has attracted considerable attention in birds and mammals, but less in other taxa, including fishes. We analysed sex-specific dispersal in historical (1910s and 1950s) and contemporary (1990s) samples of anadromous brown trout Salmo trutta. We tested the hypothesis that dispersal is unbiased using information from microsatellite DNA and applying an assignment inde...

D Bekkevold, M M Hansen, K-L D Mensberg (2004) Molecular Ecology 13: 1707-1712

Stocking impact and migration pattern in an anadromous brown trout (Salmo trutta) complex: where have all the stocked spawning sea trout gone?

2009-12-08T19:02:08Z

We examined polymorphism at seven microsatellite loci among sea trout (Salmo trutta) (n = 846) collected from three areas in the Limfjord (Denmark). We then assessed their potential population source by comparing, using a mixed stock analysis (MSA) Bayesian framework, their genetic composition to that of brown trout collected from 32 tributaries pooled into nine geographical regions (n = 3801) and...

D E Ruzzante, M M Hansen, D Meldrup, K M Ebert (2004) Molecular Ecology 13: 1433-1445

Kin-biased distribution in brown trout: an effect of redd location or kin recognition?

2008-01-31T21:06:20Z

A wide range of animals have been reported to show kin-biased behaviours, such as reduced aggressiveness and increased food sharing among relatives. However, less is known about whether wild animals also associate with relatives under natural conditions, which is a prerequisite to facilitate kin-biased behaviours and hence kin selection. We tested, by means of microsatellite polymorphism, correlat...

J Carlsson, J E L Carlsson, K H Olsén, M M Hansen, T Eriksson, J Nilsson (2004) Heredity 92: 53-60

Evidence of a hybrid-zone in Atlantic cod (Gadus morhua) in the Baltic and the Danish Belt Sea revealed by individual admixture analysis.

2009-12-08T19:04:36Z

The study of hybrid zones is central to our understanding of the genetic basis of reproductive isolation and speciation, yet very little is known about the extent and significance of hybrid zones in marine fishes. We examined the population structure of cod in the transition area between the North Sea and the Baltic Sea employing nine microsatellite loci. Genetic differentiation between the North ...

E E Nielsen, M M Hansen, D E Ruzzante, D Meldrup, P Grønkjær (2003) Molecular Ecology 12: 1497-1508

Application of molecular markers in population and conservation genetics, with special emphasis on fishes

2008-02-01T17:56:40Z

This DSc thesis, which includes 23 scientific papers and a general introduction, was accepted for defence by the Faculty of Natural Sciences, University of Aarhus in 2003. The thesis describes how molecular markers have been applied for studying the genetic population structure of brown trout (Salmo trutta), Atlantic salmon (S. salar), Atlantic cod (Gadus morhua), lake whitefish and North Sea hout...

M M Hansen (2003) Faculty of Natural Sciences, University of Aarhus, Denmark

Long-term temporal changes of genetic composition in brown trout (Salmo trutta L.) populations inhabiting an unstable environment.

2009-12-08T19:04:07Z

The genetic structure of brown trout (Salmo trutta) populations inhabiting rivers on the island of Bornholm in the Baltic Sea was studied on a spatial and temporal scale. Low water levels in the rivers during the summer period are assumed to have a significant impact on the persistence of local populations, possibly resulting in a metapopulation structure. Extinctions may, however, also be buffere...

S Østergaard, M M Hansen, V Loeschcke, E E Nielsen (2003) Molecular Ecology 12: 3123-3135

Long-term effective population sizes, temporal stability of genetic composition and potential for local adaptation in anadromous brown trout (Salmo trutta) populations.

2009-12-08T19:05:31Z

We examined the long-term temporal (1910s to 1990s) genetic variation at eight microsatellite DNA loci in brown trout (Salmo trutta L) collected from five anadromous populations in Denmark to assess the long-term stability of genetic composition and to estimate effective population sizes (Ne). Contemporary and historical samples consisted of tissue and archived scales, respectively. Pairwise theta...

M M Hansen, D E Ruzzante, E E Nielsen, D Bekkevold, K-L D Mensberg (2002) Molecular Ecology 11: 2523-2535

Male reproductive competition in spawning aggregations of cod (Gadus morhua, L.).

2009-12-08T19:06:39Z

Reproductive competition may lead to a large skew in reproductive success among individuals. Very few studies have analysed the paternity contribution of individual males in spawning aggregations of fish species with huge census population sizes. We quantified the variance in male reproductive success in spawning aggregations of cod under experimental conditions over an entire spawning season. Mal...

D Bekkevold, M M Hansen, V Loeschcke (2002) Molecular Ecology 11: 91-102

Myths and moderation in marine “metapopulations”

2009-12-08T19:07:03Z

The metapopulation concept is appearing with increasing frequency in the marine population dynamics and genetics literature, though its applicability to marine systems remains an open question. Moreover, in recent years, the meaning of the term ‘metapopulation’ has become blurred, concomitant with its increasing use. In this paper, we summarize the concept of metapopulation dynamics and the as...

R K Smedbol, A McPherson, M M Hansen, E Kenchington (2002) Fish and Fisheries 3: 20-35

Estimating the long-term effects of stocking domesticated trout into wild brown trout (Salmo trutta) populations: an approach using microsatellite DNA analysis of historical and contemporary samples.

2009-12-08T19:06:11Z

Indigenous salmonid fish gene pools are affected by domesticated conspecifics, derived from aquaculture escapes and deliberate releases. Variability was examined at nine microsatellite loci in order to assess the long-term impact of stocking domesticated trout in two brown trout populations. The study was based on analysis of two historical samples (1945-56), represented by old scale collections, ...

M M Hansen (2002) Molecular Ecology 11: 1003-1015

Does dispersal from landlocked trout explain the coexistence of resident and migratory trout females in a small stream?

2009-12-08T19:11:45Z

The hypothesis that stream-resident females of brown trout Salmo trutta occurring in sympatry with sea-migrant females in a small stream were immigrants from an up-stream allopatric landlocked population was rejected. Genetic differentiation was not detected between the sympatric forms whereas they both diverged significantly from the land-locked population. suggesting a common gene-pool for the s...

J C E Petersson, M M Hansen, T Bohlin (2001) Journal of Fish Biology 58: 2 487-495

Fisheries. Population of origin of Atlantic cod.

2008-01-31T21:24:45Z

Most of the world's cod (Gadus morhua) fisheries are now tightly regulated or closed altogether. Being able to link individual fish to their population of origin would assist enormously in policing regulations and in identifying poachers. Here we show that microsatellite genetic markers can be used to assign individual cod from three different populations in the northeastern Atlantic Ocean to thei...

E E Nielsen, M M Hansen, C Schmidt, D Meldrup, P Grønkjaer (2001) Nature 413: 6853 272

Genetic consequences of population decline in the European otter (Lutra lutra): an assessment of microsatellite DNA variation in Danish otters from 1883 to 1993.

2009-12-08T19:09:05Z

The European otter (Lutra lutra) was common in Denmark until the 1960s, but its present distribution encompasses only a minor part of the country. The aim of this study was to assess whether the recent population decline has resulted in loss of genetic variability and to gain further insight into the dynamics of the population decline. This was done by analysing microsatellite DNA variation in con...

C Pertoldi, M M Hansen, V Loeschcke, A B Madsen, L Jacobsen, H Baagoe (2001) Proceedings of the Royal Society London, Series B: Biological Sciences 268: 1775-1781

Assigning individual fish to populations using microsatellite DNA markers: Methods and applications

2009-12-08T19:12:09Z

New statistical developments combined with the use of highly polymorphic microsatellite DNA markers enable the determination of the population of origin of single fish, resulting in numerous new research possibilities and applications in practical management of fish populations. We first describe three main categories of methods available, i.e. (i) assignment tests and related methods, (ii) discri...

M M Hansen, E Kenchington, E E Nielsen (2001) Fish and Fisheries 2: 93-112

Looking for a needle in a haystack : Discovery of indigenous salmon in heavily stocked populations

2009-12-08T19:11:19Z

Microsatellite analysis of Atlantic salmon fromfive Danish rivers was performed to determinethe stocked or indigenous status ofindividuals. Genetic variation at six highlypolymorphic microsatellite loci was assayed andused for individual based analyses (assignmenttests). Contemporary samples of adult returningspawners and fry were compared to baseline datafrom: 1) historical DNA samples (from olds...

E E Nielsen, M M Hansen, L Bach (2001) Conservation Genetics 2: 219-232

Use of microsatellite markers for identification of indigenous brown trout in a geographical region heavily influenced by stocked domesticated trout

2009-12-08T19:09:51Z

Based on estimates of genetic differentiation between populations, assignment tests and analysis of isolation by distance, stocked populations of brown trout Salmo trutta of Funen Island, Denmark, had been genetically affected by domesticated trout, whereas the stocking of wild exogenous trout into one of the rivers had little or no impact. At the same time, there were clear indications of remaini...

N G Fritzner, M M Hansen, S S Madsen, K Kristiansen (2001) Journal of Fish Biology 58: 1197-1210

Admixture analysis and stocking impact assessment in brown trout (Salmo trutta), estimated with incomplete baseline data

2009-12-08T19:10:25Z

Studies of genetic interactions between wild and domesticated fish are often hampered by unavailability of samples from wild populations prior to population admixture. We assessed the utility of a new Bayesian method, which can estimate individual admixture coefficients even with data missing from the populations contributing to admixture. We applied the method to analyse the genetic contribution ...

M M Hansen, E E Nielsen, D Bekkevold, K L D Mensberg (2001) Canadian Journal of Fisheries and Aquatic Science 58: 1853-1860

Distribution of individual inbreeding coefficients, relatedness and influence of stocking on native anadromous brown trout (Salmo trutta) population structure.

2009-12-08T19:07:27Z

We examined polymorphism at seven microsatellite loci in 4023 brown trout (Salmo trutta) collected from 32 tributaries to the Limfjord, Denmark (approximately 200 km) and from two hatcheries used for stocking. Populations differ in their estimated sizes and stocking histories. Mean individual inbreeding coefficients do not differ among locations within rivers. Relatedness varies between sites with...

D E Ruzzante, M M Hansen, D Meldrup (2001) Molecular Ecology 10: 2107-2128

Brown trout (Salmo trutta) stocking impact assessment using microsatellite DNA markers

2009-12-08T19:10:50Z

The genetic integrity of many salmonid fish populations is threatened by stocking of domesticated conspecifics. The purpose of this study was to assess the utility of microsatellite DNA markers for detecting loss of genetic diversity in hatchery strains, for estimating their genetic relationships, and for monitoring the genetic impact of stocking activity on wild populations of salmonid fishes. Br...

M M Hansen, D E Ruzzante, E E Nielsen, K L D Mensberg (2001) Ecological Applications 11: 148-160

Genetic monitoring of supportive breeding in brown trout (Salmo trutta L.), using microsatellite DNA markers

2009-12-08T19:13:04Z

Stocking with offspring of local wild fish, so-called supportive breeding, is often advocated as an alternative to stocking domesticated fish. However, it is important to ensure that supportive breeding does not result in inbreeding and loss of genetic variability. We analysed eight microsatellite loci in samples of wild and hatchery-reared brown trout (Salmo trutta) from three populations subject...

M M Hansen, E E Nielsen, D E Ruzzante, C Bouza, K L D Mensberg (2000) Canadian Journal of Fisheries and Aquatic Science 57: 2130-2139

Microsatellite and mitochondrial DNA polymorphism reveals life-history dependent interbreeding between hatchery and wild brown trout (Salmo trutta L.).

2009-12-08T19:12:29Z

The effects of stocking hatchery trout into wild populations were studied in a Danish river, using microsatellite and mitochondrial DNA (mtDNA) markers. Baseline samples were taken from hatchery trout and wild trout assumed to be unaffected by previous stocking. Also, samples were taken from resident and sea trout from a stocked section of the river. Genetic differentiation between the hatchery st...

M M Hansen, D E Ruzzante, E E nielsen, K L Mensberg (2000) Molecular Ecology 9: 583-594

Identification of mustelid species : otter (Lutra lutra), American mink (Mustela vison) and polecat (Mustela putorius), by analysis of DNA from faecal samples

2009-12-08T19:13:59Z

The abundance of mink, otter, and polecat may be inferred from records of their seats, and the feeding biology of the species is often studied by analysis of skeletal remains and other hard parts in faeces. However, in some situations it is difficult to distinguish between faeces from these three mustelid species. A method is described for assigning faeces to these three mustelid species, based on...

M M Hansen, L Jacobsen (1999) Journal of Zoology 247: 177-181

Genetic variation in time and space : Microsatellite analysis of extinct and extant populations of Atlantic salmon

2008-01-31T22:01:05Z

Information on genetic composition of past and present populations may be obtained by analyzing DNA from archival samples. A study is presented on the genetic population structure of extant and extinct local populations of Atlantic salmon from 1913 to 1989 using dried scales as a source of DNA. Variation at six microsatellite loci was studied. Tests for differentiation among populations and among ...

E E Nielsen, M M Hansen, V Loeschcke (1999) Evolution 53: 261-268

Analysis of DNA from old scale samples : technical aspects, applications and perspectives for conservation

2008-01-31T21:59:52Z

Collections of old scales from salmonid fishes can be found in many fisheries institutions in Europe and North America. Such scales have been shown to be useful as a source of DNA, which can be used for analysis of microsatellites. We here describe the technical procedures in relation to extraction and PCR amplification of DNA from old scales. Further, we describe case stories of the application o...

E E Nielsen, M M Hansen, V Loeschcke (1999) Hereditas 130: 265-276

Postglacial recolonization patterns and genetic relationships among whitefish (Coregonus sp.) populations in Denmark, inferred from mitochondrial DNA and microsatellite markers

2009-12-08T19:14:25Z

The genetic relationships among morphologically and geographically divergent populations of whitefish (genus: Coregonus) from Denmark and the Baltic Sea region were studied by analysis of microsatellites and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of mitochondrial DNA (mtDNA) segments, The endangered North Sea houting (classified as C. oxyrhynchus) di...

M M Hansen, K L D Mensberg, S Berg (1999) Molecular Ecology 8: 239-252

Development of new VNTR markers for pike and assessment of variability at di- and tetranucleotide repeat microsatellite loci

2009-12-08T19:13:34Z

Levels of variation at six VNTR (variable number of tandem repeats) loci, one minisatellite and five microsatellite loci, isolated from tri- and tetranucleotide enriched DNA libraries for northern pike were generally low in two Danish populations (1-4 alleles; expected heterozygosity 0-0.57), though one highly variable microsatellite (13 alleles; expected heterozygosity 0.79) was identified. In co...

M M Hansen, J B Taggart, D Meldrup (1999) Journal of Fish Biology 55: 183-188

Improved primer sequences for the mitochondrial ND1, ND3/4 and ND5/6 segments in salmonid fishes : application to RFLP analysis of Atlantic salmon

2009-12-08T19:14:56Z

New specific primers for the mtDNA segments ND1, ND3/4 and ND5/6 designed from the rainbow trout sequence, improved PCR amplification for salmonid fishes. RFLP analysis revealed restriction site variation for all three segments in Atlantic salmon. Eleven haplotypes were detected in a screening of 30 individuals from four European populations. (C) 1998 The Fisheries society of the British Isles

E E Nielsen, M M Hansen, K L D Mensberg (1998) Journal of Fish Biology 53: 216-220

Genetic differentiation and relationship between genetic and geographical distance in Danish sea trout (Salmo trutta L.) populations

2008-02-01T07:01:16Z

Twenty-four samples of anadromous brown trout from four river systems/geographical regions were studied by PCR-RFLP analysis of the ND-1 and ND-5/6 regions of the mitochondrial genome. A total of 14 haplotypes was observed, and these could be divided into three phylogenetic groups. Populations within river systems/regions tended to be more closely related to each other than to populations from oth...

M M Hansen, K L D Mensberg (1998) Heredity 81: 493-504

Analysis of microsatellite DNA from old scale samples of Atlantic salmon Salmo salar : A comparison of genetic composition over 60 years

2009-12-08T19:15:42Z

Microsatellite analysis was applied to scale samples of Atlantic salmon collected up to 60 years ago. Samples from the 1930s, from a now endangered Danish population, were compared with recent samples (1989), to test if the present population consists of descendants from the original one. Allele frequencies had changed over time, but individuals from the two samples caught about 60 years apart clu...

E E Nielsen, M M Hansen, V Loeschcke (1997) Molecular Ecology 6: 487-492

Genetic variation within and among Danish brown trout (Salmo trutta L) hatchery strains, assessed by PCR-RFLP analysis of mitochondrial DNA segments

2008-02-01T18:23:22Z

Eleven Danish brown trout hatchery strains were studied by PCR-RFLP analysis of the ND-I and ND-5/6 segments of the mitochondrial genome. For comparison, data from wild trout representing three Danish river systems also were included. Reduced variability in terms of nucleon diversity and number of haplotypes was observed in most hatchery strains. However, computer simulations showed that even with...

M M Hansen, K L D Mensberg, G Rasmussen, V Simonsen (1997) Aquaculture 153: 15-29

The problem of sampling families rather than populations : Relatedness among individuals in samples of juvenile brown trout Salmo trutta L

2009-12-08T19:15:17Z

In species exhibiting a nonrandom distribution of closely related individuals, sampling of a few families may lead to biased estimates of allele frequencies in populations. This problem was studied in two brown trout populations, based on analysis of mtDNA and microsatellites. In both samples mtDNA haplotype frequencies differed significantly between age classes, and in one sample 17 out of 18 ind...

M M Hansen, E E Nielsen, K L D Mensberg (1997) Molecular Ecology 6: 469-474

Temporal variation in mitochondrial DNA haplotype frequencies in a brown trout (Salmo Trutta L) population that shows stability in nuclear allele frequencies

2008-02-01T18:10:11Z

M M Hansen, V Loeschcke (1996) Evolution 50: 454-457

Founder effects and genetic population structure of brown trout (Salmo trutta) in a Danish river system

2009-12-08T19:16:19Z

The influence of founder effects on the genetic population structure of brown trout (Salmo trutta) was studied in a small Danish river system. Samples of trout from seven locations were analysed by allozyme electrophoresis and mitochondrial DNA restriction fragment length polymorphism analysis. For comparison, allozyme data from other Danish trout populations and mtDNA data from two hatchery strai...

M M Hansen, K L D Mensberg (1996) Canadian Journal of Fisheries and Aquatic Science 53: 2229-2237

Genetic structure of European populations of Salmo salar L (Atlantic salmon) inferred from mitochondrial DNA

2008-02-01T18:08:47Z

The genetic relationships between the only natural population of Atlantic salmon (Salmo salar L.) in Denmark and seven other European salmon populations were studied using RFLP analysis of PCR amplified mitochondrial DNA segments. Six different haplotypes were detected by restriction enzyme analyses of the NADH dehydrogenase 1 segment, employing four endonucleases. Significant genetic differentiat...

E E Nielsen, M M Hansen, V Loeschcke (1996) Heredity 77: 351-358

Genetic differentiation among Danish brown trout populations, as detected by RFLP analysis of PCR amplified mitochondrial DNA segments

2009-12-08T19:16:45Z

An initial screening with 18 restriction endonucleases of brown trout mitochondrial DNA from three regions of Denmark revealed no variation in the D-loop while seven restriction endonucleases were found to detect variability in the NADH-dehydrogenase 1 and/or 5/6 regions. Thirteen different haplotypes were observed, fewer in the Lake Hald populations than in the other samples, probably a result of...

M M Hansen, V Loeschcke (1996) Journal of Fish Biology 48: 3 422-436

Assessment of the stocked or wild origin of anadromous brown trout (Salmo trutta L) in a Danish river system, using mitochondrial Dna RFLP analysis

2009-12-08T19:17:09Z

Declines in the number of anadromous brown trout in the Karup River in Denmark, due to environmental degradation, led to the stocking of large numbers of hatchery trout during the 1980s. This practice was gradually replaced by stocking with the offspring of electrofished local trout. The genetic contribution of the hatchery fish to the current population of anadromous trout in the river was estima...

M M Hansen, R A Hynes, V Loeschcke, G Rasmussen (1995) Molecular Ecology 4: 189-198

Genetic differentiation among Danish brown trout (Salmo trutta L.) populations and interactions between wild and hatchery-reared trout

2008-01-31T11:40:54Z

M M Hansen (1994)

Effects of releasing hatchery-reared brown trout to wild trout populations

2008-01-31T10:38:37Z

M M Hansen, V Loeschcke (1994) Conservation Genetics 273-289

Genetic differentiation among Danish brown trout Salmo trutta populations

2008-02-01T18:00:33Z

Brown trout (Salmo trutta L.) from twelve locations in small rivers in Jutland, Denmark, were examined by allozyme electrophoresis. Seven of the locations are tributaries to the small (3.3 km2) Lake Hald. These and two other locations are assumed to have been mainly inaccessible to gene flow from outside for hundreds of years because of impassable dams. The levels of polymorphism indicated that li...

M M Hansen, V Loeschcke, G Rasmussen, V Simonsen (1993) Hereditas 118: 177-185

2008-04-18T19:37:30Z

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2008-04-18T19:35:16Z

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