Genetic variation
-how is it measured among and within populations
within populatioons often measured as:
- heterozygosity
- allelic richness
among populations measured as Fst
what is an allele?
=any of several froms of a gene, usually arising through mutations
Genetic introgression
incorporation of genes from a donor population to a recipient population through hybridization,
e.g. farmed →wild salmon
what si evolution ?
any change in allele frquency
what are evolutionary forces ?
- muatation
- genetic drift
- gene flow
- natural selectiom
what is gene flow?
gene ftransfer from on to another population
what effect has gene flow within and between populations?
within : increases genetic variation
betwe. decreases genetci variation
what is natural selection :
different survival +reproduction betw. indiviudlaes due to different pehnotype (diff. genotyp)
what is genetic drift?
random changes in allel frequency in an allele pool
how does genetci drift effects small and how large populations?
Large in small populations and small in large populations. →increases genetic differences between populations and increase loss of genetic variation within populations.
what is the effective popuation size, Ne?
is the sizeof a statisticallly ideal popuation
what is the definition of an “ideal population” ?
- panmixia
- n(females)=n(males)
- no random genetic drift
- no mutatsion
- no migration
- no natural selection
what is outbreeding depression ?
=Reduced fitness in offspring from interbreeding between genetically distant individuals
e.g. populations adapted to dif. environments
what is inbreeding depression ?
closely related individuals give offspring of lower fitness than unrelated individuals
what does the HW-Law say?
in an ideal population is the frequencies of the genotypes determined by the frequencies of the alleles.
what is the ryman laike effect?
= increase in inbreeding and a reduction of the total effective population size; occurs when few parents produce large number ofoffsprings
what are indrect genetic effects from relase of cultured fish?
- may compete for:
+food (at high and at low food availability)
+shelter
+mates
+introduce parasites and disease (g.salaris)
–> indreict reduced pop.size and genetic variation, add extra selection pressure
how can escaped salmon be identified?
- their scale (farmed salmon even growth)
- morphology (fin damages, fat or skinny)
- DNA (SNP’s search for genetic differences betw. farmed and wild salmon )
what are the two breeding stragies?
delibertely release-stocking
non- delibertely release-stocking –> escaped farmed salmon
why deliberately release ?
to try to preserve genetic variation and integrity –> prevent inbreeding depression
what are guidelines for delberately release?
- only use fish from local population
- stock as juvenile stages as possible
to what rivers go escaped salmon to spawn?
river wich are not to steep
and have a lot of water
what is the life cycle of atlantic salmon?
- born in river
- spend 1-5 years in river beforer entering the sea
- migrate to the sea –> grow large (1-5 years)
- homing –> spawing
what is homing?
salmon return to the birth-river –> spawns in the same
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kjellinge_kahoot7
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parasites43
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sea_lice70
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introduction10
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non-native_species30
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modellingof_oceancirculation25
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biofouling31
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IMTA19
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epibiosis15
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aquaculture_inthefuture26
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diseases_infectiondynamics&biosecurity49
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environmental.legislation_state.assesment31
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genetic_interactions30
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monitoring_systems:watercolumn-seafloor40
