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BIO152H5 (270)
Maria Arts (237)
Lecture 15

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Maria Arts

Lecture 15 INBREEDING AND GENETIC DIVERSITY Can Research 251 DIVERSITY1 of ecosystems 2 variety of species species richness relative abundance3 genetic diversity with speciesTwo elements intraspecific variation or gene diversity interspecific variation or species diversity Gene Diversity outlinegenetic considerations small population sizeinterbreedingdemographic considerations immigrationemigrationconnectivity gene flowGenetic Consequences of Small Population Sizeloss of genetic diversity byo population bottlenecks o founder effects o genetic drift take alleles from large pop and now are in small pop inbreeding inbreeding depressionfixation of deleterious genes Inbreeding mating between relativesselfing Share alleles inherited by common ancestor Only heterozygote produce heterozygote offspring but only 50 of the time The other half is homozygous individuals 121 ratio HW Going from parental to g4 to g5 shrink heterozygous and increase homozygous individuals increases homozygosity in small pops hetero wipe out quicker does not cause evolution because allele frequencies do not change in the population as a whole inbreedingchanges genotype frequencies but not AF Evolution can occur by mutation or immigration where pop structure changes Inbreeding Depression decline in average fitness in a population that takes place whenhomozygosity increases and heterozygosity decreases fitness difference bw noninbred and inbred individuals 2 processes of Inbreeding Depressionmany recessive alleles represent loss of function mutationsmore heterozygotes have this allele but after inbreeding reduction in viability as these alleles are lethal andincrease rate at which natural selection exposes disadvantageous recessive alleles in the homozygous phenotype Therefore more exposure means evolutionary change increases because purifying selection can eliminate deleterious recessive alleles many genes involved in fighting disease have a heterozygote advantage
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