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Projects / Programmes source: ARIS

Conservation genetics of indigenous brown trout in Slovenia

Research activity

Code Science Field Subfield
4.02.01  Biotechnical sciences  Animal production  Genetics and selection 

Code Science Field
B220  Biomedical sciences  Genetics, cytogenetics 

Code Science Field
4.02  Agricultural and Veterinary Sciences  Animal and Dairy science 
Keywords
Salmo trutta, brown trout, Slovenia, extinction, Atlantic evolutionary lineage, molecular markers, mtDNA, microsatellites, SNP, hybridization, introgression, adaptive variation, environment, selection, immune response
Evaluation (rules)
source: COBISS
Researchers (5)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  37309  PhD Jernej Bravničar  Animal production  Technical associate  2014 - 2017  36 
2.  35373  PhD Ida Djurdjevič  Animal production  Junior researcher  2014 - 2017  35 
3.  05008  PhD Mojca Narat  Biotechnology  Researcher  2014 - 2017  688 
4.  11906  PhD Aleš Snoj  Animal production  Head  2014 - 2017  219 
5.  15658  PhD Simona Sušnik Bajec  Biochemistry and molecular biology  Researcher  2014 - 2017  194 
Organisations (1)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0481  University of Ljubljana, Biotechnical Faculty  Ljubljana  1626914  66,255 
Abstract
The Slovenian indigenous populations of brown trout (Salmo trutta; the Danubian evolutionary lineage) are highly endangered due to domestic Atlantic brown trout lineage, which has been largely stocked in Slovenian waters, causing extensive hybridization between introduced and indigenous individuals. Stocking with domestic brown trout is economically inefficient, because, due to genetic adaptation to captivity they are maladaptive in the wild, where less than 10 % of stocked individuals survive; it is also harmful from conservation perspective as stocked domestic trout genetically admix with local individuals, which leads to hybrid swarms, loss of genetic adaptability of indigenous populations to specific wild environment, changes of locally characteristic phenotypes, and in the worst case, loss of self-sustainability of introgressed populations followed by their collapse and extinction. Loss of adaptation ability to the wild can affect also indigenous Danubian brown trout when intensively reared under farm conditions, especially if long-term exploitation of breeding stock and prolonged retention of fry in hatchery are performed. Hatchery-rearing usually causes also population bottlenecks followed by loss of genetic diversity of progeny to be stocked, and additionally reduces its survival in the wild.   According to the past genetic research done on the brown trout in Slovenia, all the breeding stocks and most of the natural brown trout populations screened turned out as highly introgressed with domestic Atlantic genes; non-introgressed (»pure«) populations are scarce; only nine of them were found, all being confined to the upper reaches of some isolated tributaries, exhibiting territorial genetic profiles, very low genetic diversity and effective population size, which makes them unsuitable material for restoring brown trout in its entire range in Slovenia.   The objectives of the proposed project are as follows: • to find additional sources of genetically pure populations. • to establish a system of molecular markers with which it will be possible to distinguish between the genetic profiles, specific to each local population. • to identify the genetic profile (e.g., in the context of molecular markers related with MHC complex), which is typical for specific environment (e.g., farm, natural environment). • to make proposals for measures destined to repopulation of indigenous brown trout in Slovenia   Across all the fishing areas in the Sava and Drava river system, about 70 locations (20-30 fish per location) will be electro-fished for fin-clips used for DNA extraction. After the sampling process, fish will be returned to the site of catch. The sampling locations will be sorted out on the basis of phenotypic uniformity of the trout, impassability for the fish inhabiting downstream area from the location, fishery cadastral register information, etc. Sampling will be conducted in collaboration with the angling clubs and Fisheries research institute of Slovenia. We tend to analyzed (1) nucleotide sequence of the control region of mtDNA (for phylogenetic and phylogeographic analysis), (2) single nucleotide polymorphisms of nuclear DNA specific for Danubian and Atlantic lineage of brown trout (to determine the degree of introgression), (3) neutral microsatellite loci to determine basic population genetic parameters (F-statistic, genetic diversity and divergence, genetic structure etc.) and design DNA "fingerprinting" assay, (4) microsatellite loci linked to genes with adaptive value (e.g., immune response: the loci UBA, TAP2A inTAP2B), which are under the selection pressure. The analysis of both groups of microsatellite loci will be used to measure the outcome of field experiment, designed to determine the selection impact of different environment on genetics of brown trout, which will be in the stage of eyed eggs introduced into different kind of environments, but will be identical by origin.   We expect to identify populations of
Significance for science
V okviru analiz predlaganega projekta bomo uporabljali obstoječa molekularna orodja in pristope, zato projekt ne bo neposredno vplival na razvoj bazičnih znanosti. Bo pa doprinesel k širšemu poznavanju molekularne ekologije potočne postrvi, predvsem bo dopolnjeno poznavanje filogeografije te vrste; za območje Slovenije namreč še ni natančnih podatkov o prisotnosti vseh evolucijskih linij in o njihovi geografski razporejenosti, zato niti ni možno sklepanje o kolonizacijskih in demografskih potekih potočne postrvi, ki so vplivali na razporejenost njenih populacij na območju Slovenije. To bodo rezultati projekta omogočili. Novost na področju genomike bo predstavljala študija adaptivnih sprememb, izvedena v okviru poljskega poskusa, preko katerega bomo spremljali vpliv različnih selekcijskih pritiskov na genetske profile živali, ki bodo v fazi iker z očmi naseljene v različna okolja, vendar bodo po poreklu identične. Po našem vedenju tak poskus še ni bil izveden na salmonidih.
Significance for the country
Glavni pomen rezultatov predlaganega projekta je varovanje naravne dediščine, katere del v Sloveniji je nedvomno tudi avtohtona potočna postrv, ki je bila upodobljena celo na kovancu slovenskega tolarja. Projekt je izrazito praktično usmerjen in je namenjen kot neposredna pomoč pri izdelavi varstvenega načrta za avtohtono potočno postrv v Sloveniji s končnim ciljem njene repopulacije. Podatke o lokacijah genetsko čistih donavskih populacij bomo posredovali MKO in ZZRS, ribiškim družinam in Ribiški zvezi Slovenije, ki bodo to informacijo implementirali v ukrepe za obnovo populacije avtohtone potočne postrvi, hkrati pa bo služila pri strateškem odločanju glede upravljanja rib v slovenskih celinskih vodah. Sistem molekularnih markerjev za regijsko in intra-populacijsko ločevanje osebkov bo omogočal ugotavljanje identitete posameznih populacij potočne postrvi in s tem tudi sledenje in nadziranje njihovega prenašanja izven dovoljenega geografskega območja. S pomočjo »DNA fingerpritinga« bo v populacijah možno ločevati med posameznimi osebki, kar bo služilo kot orodje za izvajanje dodatnih populacijskih analiz (e.g., starševska analiza, ocena efektivne velikosti populacije), to pa bo doprineslo k poznavanju populacijske dinamike preučevane populacije in preko tega do ocene njene genetske viabilnosti, ki predstavlja ključen parameter za ocenjevanje ogroženosti populacije in ga bodo lahko ribiški upravljavci vključili v svoj načrt upravljanja. Študij vpliva dednosti in selekcije na prilagojenost potočnih postrvi na določeno okolje bo z znanstvenim pristopom ovrednotil opažanje nekaterih slovenskih ribiških upravljavcev, ki poročajo, da poribljanje odprtih vod z ribogojniškimi populacijami potočnih postrvi pri njih ni učinkovito in da ima zarod potočnih postrvi iz divjine v ribogojnici izjemno nizek »fitness«. Hkrati bo to nova potencialna smernica za izboljšano strategijo upravljanja s potočno postrvjo.
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