* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Lecture 10
Hybrid (biology) wikipedia , lookup
Viral phylodynamics wikipedia , lookup
Dual inheritance theory wikipedia , lookup
Designer baby wikipedia , lookup
Genetic studies on Bulgarians wikipedia , lookup
Pharmacogenomics wikipedia , lookup
Genetic code wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Medical genetics wikipedia , lookup
Genetics and archaeogenetics of South Asia wikipedia , lookup
History of genetic engineering wikipedia , lookup
Behavioural genetics wikipedia , lookup
Polymorphism (biology) wikipedia , lookup
Public health genomics wikipedia , lookup
Genetic engineering wikipedia , lookup
Heritability of IQ wikipedia , lookup
Genome (book) wikipedia , lookup
Koinophilia wikipedia , lookup
Genetic testing wikipedia , lookup
Inbreeding avoidance wikipedia , lookup
Genetic drift wikipedia , lookup
Human genetic variation wikipedia , lookup
Lecture10TakeHomePoints • GeneticStochasticity -Randomfluctuationinallelefrequenciescanleadtolossofparticulargenotypes andfixationofparticulartraits. -Smallfounderpopulationsinherentlycontainlimitedgeneticdiversity,and inbreedingandgeneticdriftcanenhancethelossofdiversity. -Inbreeding:Populationsthathaveahighfrequencyofcloselyrelatedindividuals cansufferfrominbreeding.Ininbredpopulations,deleteriousallelescanbe exposedinhomozygousindividuals,whichmayreducefitness.Theimportanceof inbreedingvarieswithspecies. PotentialGeneticConsequencesofInvasion GeneticBottleneckandFounderEffect Constrainedgeneticdiversity–smallpopulationsample GeneticDrift Randomlossofallelesinsmallpopulations InbreedingDepression Consequencesofdeleteriousrecessivegenesbecomingapparentthrough inbreeding GeneticHotspots Repeatedintroductionsleadtohyperdiversityandthepotentialfornovel invasivegenotypes GeneticDiversityandInvasion Invasionsofteninvolveasmallsampleoftheoriginalpopulation Throughrandomchance,canoverorunderrepresentparticulargenotypes AreBottlenecksBadforInvaders? Yes Reducedgeneticdiversity Lessforselectiontoacton,thuslessresponsivetovariableenvironments Expressionofdeleteriousallelesthroughinbreeding Inbreedingdepression andNo Genetic‘purging’ Advantageofrelatedness Manyinvasivespeciesarenotreallybottlenecked Geneticpurging–moderatelyinbredpopulationscansheddeleteriousallelesover severalgenerationsasselectionactsagainstthem.Afteranumberofgenerations, thefitnessincreasestothatofoutbredpopulations. Harmoniaaxyridis(Harlequinladybeetle) Underwentabottleneckofintermediateintensity Relatedindividualshadanincreasedprobabilityofmating,increasingthe homozygosityofthepopulation. Deleteriousrecessivealleleswerethenpurgedfromthefrompopulationafter~15 generationsbecauseonceexposed(asahomozygousrecessive),naturalselection eliminatedthem • GeneticConsequencesofInvasion • Lowgeneticdiversity • Mayhavenegative,neutral,orpositive(shortterm)effects • Lowgeneticdiversity–canlimitresponsestoenvironmental stochasticity.Canlimitabilityofapopulationtoadapttonovel environments.Maycontributetoinbreeding. • Insomesocialinsects,lowgeneticdiversitycanfacilitatemuch higherpopulationdensitiesasindividualcoloniesfailto recognizeotherindependentcoloniesasdistinctpreventing theaggressionthatmaintainslowerpopulationdensitywhere thespeciesarenative. • Highgeneticdiversity • Ininvasions,usuallytheproductofrepeatedintroductions • Higherdiversitywithinpopulationsthanbetweenthem. Thiscontrasttonativerangewhereindividual populationsaregeneticallydistinctandmostvariation isbetweenpopulationsasopposedtowithin. • BrownanoleinS.Floridaisagoodexample. • • Foundereffect–gypsymothinNorthAmerica(largelyasingle introduction)butnotraccoonsinGermany(multipleindependent introductions). • Lagtimes–maybeaproductoflowgeneticvariabilityand maladaptationtonovelenvironment • Overcomethroughdenovomutation,geneflowfromanother population,orselectionontheexistingvariationwithinthe population.