Research Activities                               Go Back!

Laboratory:
Division of Population Biology, Institute of Zoology, University of Berne, Switzerland.
Contact person (name and e-mail):
Carlo Rodolfo Largiadèr, largiader@zoo.unibe.ch
Persons working on brown trout population genetics:
Maya Mezzera, Bruno Schneider (University of Zurich), Carlo R. Largiadèr, Adolf Scholl
General research topics of the laboratory:
Conservation and Management, Phylogeography, Reproduction biology , Population structure.
General description of research on brown trout population genetics:
A major research topic of our laboratory is the conservation and management of brown trout. In particular, we study the genetic effects on local populations through introductions of hatchery trout (or through exchanges of wild trout across major watersheds). Another important topic is the phylogeography of brown trout since we depend on correct identification of the autochthonous form for the study of interactions between introduced and native trout. Because of the long tradition of intensive stocking of brown trout populations and because natural exchanges of fish communities across major watersheds (e.g. Black Sea - Atlantic Sea) could have occurred in Switzerland after the last glaciations, we started to carry out phylogeographic studies on less „disturbed" freshwater species (e.g. Cottus gobio) in order to infer natural colonisation patterns of the Alpine region by different brown trout forms. Furthermore, some of our studies address the relationship between migratory Lake trout and sedentary trout and the mating system of brown trout.

Protein electrophoresis, microsatellites, mtDNA PCR-RFLP are the major molecular tools that are employed in these studies.

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List of projects (brown trout) for the past 3 years:

 

Study #1
Researcher: Maya Mezzera (M.Sc. student), Adolf Scholl (supervisor), Carlo R. Largiadèr (co-supervisor)
Source of project funding: Fisheries administrations of diverse Swiss cantons & in house.
Topic: Stocking effects.
Objective: To compare introgression rates between different age classes in a stocked population and to assess genetic incompatibilities between introduced and native trout forms.
Design: Samples from age classes 0+, 1+.,2+ and a reference sample from the local hatchery strain used for stocking were analysed at „diagnostic" loci. Reciprocal crosses between native and hatchery trout were reared under hatchery conditions.
Methodology: Protein electrophoresis.
Trout population: Resident population (& Hatchery stock).
Origin of samples: Switzerland, Mediterranean Sea Basin (& Atlantic Basin).
Status: Started in Nov. 1994 and was completed in June 1996.

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Study #2
Researcher: Maya Mezzera (PhD student), Adolf Scholl (supervisor), Carlo R. Largiadèr (co-supervisor)
Source of project funding: Federal Office of Environment, Forests and Landscape (FOEFL) of Switzerland.
Topic: Stocking effects, stocking efficiency, selective angling.
Objective: To study selective fishing pressure by anglers on native and introduced trout and their hybrids.
Design: The genetic composition of trout samples caught by anglers is compared with samples obtained by electrofishing. Several factors such as time of capture, angling technique, age, body size are included into the analysis.
Methodology: Single locus microsatellite DNA.
Trout population: Resident population.
Origin of samples: Switzerland, Mediterranean Sea Basin.
Status: Started in 1997 as part of M.M.’s PhD thesis, will be completed in 1999.

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Study #3
Researcher: Maya Mezzera (PhD student), Adolf Scholl (supervisor), Carlo R. Largiadèr (co-supervisor)
Source of project funding: Federal Office of Environment, Forests and Landscape (FOEFL) of Switzerland.
Topic: Stocking effects , stocking efficiency.
Objective: To assess „survival rates" of different genotype classes (native and introduced trout and their hybrids) by studying the temporal variation of admixture and introgression rates within cohorts of a stocked population.
Design: The population is regularly re-sampled over a period of three years and the genetic composition of all subsamples of the same cohort is compared.
Methodology: Single locus microsatellite DNA.
Trout population: Resident population (& Hatchery stock).
Origin of samples: Switzerland, Mediterranean Sea Basin (& Atlantic Basin).
Status: Started in 1997 as part of MM PhD thesis, will be completed in 2000.

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Study #4
Researcher: Carlo R Largiadèr
Collaborators: René Guyomard and Arnaud Estoup, Laboratoire de Génétique des Poissons, INRA, F- 78352 Jouy-en-Josas (France); Alexis Champignuelle; Station d’Hydrobiologie Lacustre, INRA, F-74203 Thonon-les-Bains (France)
Source of project funding: Swiss National Science Foundation & in house.
Topic: Reproduction biology.
Objective: To study polyandry, intraspecific redd superimposition and assortative mating between native and introduced trout.
Design: Polyandrous redds were detected and analysed based on the genotype composition of egg samples and on the corresponding maternal genotype Redd superimposition and assortative mating between native and introduced trout were assessed by analysing the distribution of egg-genotypes within and among a large number of redds, respectively.
Methodology: Single locus microsatellite DNA, mtDNA-RFLP.
Trout population: Resident population.
Origin of samples: France, Mediterranean Sea Basin.
Status: Started in 1995 during CRL’s postdoctoral stay at the Laboratoire de Génétique des Poissons (INRA) in Jouy-en-Josas (France).

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Study #5
Researcher: Carlo R Largiadèr
Collaborators: René Guyomard and Arnaud Estoup, Laboratoire de Génétique des Poissons, INRA, F- 78352 Jouy-en-Josas (France); Alexis Champignuelle; Station d’Hydrobiologie Lacustre, INRA, F-74203 Thonon-les-Bains (France)
Source of project funding: Swiss National Science Foundation & in house.
Topic: Stocking effects.
Objective: To study cytonuclear introgression patterns on a microgeographic scale in a stocked population.
Design: A small creek (25 km) was divided into 14 sectors of about equal length and trout samples from each sector and three reference samples from the main river were genetically analysed and compared.
Methodology: Single locus microsatellite DNA, mtDNA-RFLP.
Trout population: Resident population.
Origin of samples: France, Mediterranean Sea Basin.
Status: Started in 1995 during CRLs postdoctoral stay at the Laboratoire de Génétique des Poissons (INRA) in Jouy-en-Josas (France) and will be completed in 1998.

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Study #6
Researcher: Bruno Schneider (PhD student), Carlo R Largiadèr
Collaborators: Vinzenz Ziswiler (supervisor)
Source of project funding: University of Zurich.
Topic: Stocking effects, gene diversity, gene flow, temporal variation.
Objective: To study the genetic relationship between migratory and stream resident populations of Lake Zurich.
Design: Within this system two trout morphs can be distinguished by their growth pattern The genetic composition of samples of „slow" (presumably resident trout) and „fast" growing individuals (presumably migratory trout) are compared within and among localities.
Methodology: Single locus microsatellite DNA.
Trout population: Resident population, potamodromous.
Origin of samples: Switzerland, Atlantic North Sea Basin.
Status: Started in 1997 and will be completed in 1998.

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Publications (brown trout genetics)

Journal papers:

  • Estoup, A, Largiadèr, C R , Perrot, E & Chourrout, D (1996) Rapid one-tube DNA extraction for reliable PCR detection of fish polymorphic markers and transgenes Mol Mar Biol Biotech, 5, 295-298.
  • Largiadèr, C R& Scholl, A (1994) Untersuchungen zur genetischen Variabilität bei einheimischen Forellen Mitteilungen zur Fischerei, 52, 35-45.
  • Largiadèr, C R & Scholl, A (1996) Effects of stocking on the genetic diversity of brown trout populations of the Adriatic and Danubian drainages in Switzerland J Fish Biol, 47 (Supplement A), 209-225.
  • Largiadèr, C R & Scholl, A (1996) Cellulose acetate electrophoresis for screening transferrin polymorphism in brown trout (Salmo trutta) populations In Advances in Life Sciences: Endangered Freshwater Fish in Europe (Kirchhofer, A & Hefti, D, eds), pp 199-202. Basel/Switzerland: Birkhäuser Verlag.
  • Largiadèr, C R & Scholl, A (1996) Genetic introgression between native and introduced brown trout (Salmo trutta L) populations in the Rhône River basin Mol Ecol, 5, 417-426.
  • Largiadèr, C R, Guyomard, R & Roche, P (1996) Evidence for natural reproduction of Atlantic salmon (Salmo salar L) in a French tributary of the Rhine based on genetic analysis of eggs collected from redds Bulletin Français de la Pêche et de la Pisciculture 343, 183-188.
  • Largiadèr, C R, Scholl, A & Guyomard, R (1996) The role of natural and artificial propagation on the genetic diversity of brown trout (Salmo trutta L) of the upper Rhône drainage In Advances in Life Sciences: Endangered Freshwater Fish in Europe (Kirchhofer, A & Hefti, D, eds), pp 181-197. Basel/Switzerland: Birkhäuser Verlag.
  • Mezzera, M, Largiadèr, C R & Scholl, A (1997) Discrimination of native and introduced brown trout in the River Doubs (Rôhne drainage) by number and shape of parr marks J Fish Biol, 50, 672-677.

Theses (eg, PhD and MSc theses):

  • Mezzera, M (1996) Untersuchungen über die Hybridisierung zwischenautochthonen Forellen und eingestzten Zuchtforellen im Doubs Diploma Thesis, University of Berne.
  • Largiadèr, C R (1995) Genetische Differenzierung der Forellen (Salmo trutta L) in der Schweiz und der Einfluss von Besatz auf die Lokalpopulationen PhD Thesis, University of Berne.

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