Lecture 17 - BIO220

Loci become monomorphic homozygous signalling a loss

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Unformatted text preview: more significant. Loci become monomorphic (homozygous), signalling a loss of genetic variation Partitioning genetic diversity Heterozygosity: within individuals What happens genetically to declining populations ? • Genetic drift is enhanced Among individuals in a population – Chance changes in gene frequency increase in size – Loss of genetic variation as alleles fix randomly • Inbreeding becomes more common – Heterozygosity reduced – Inbreeding depression from exposure of rare, recessive alleles – Loss of heterozygote advantage for fitness Among populations 5 6 -Inbreeding Depression: as a result of the small breeding pool, rare a nd deleterious alleles multiply in frequency -Net Result: Genotype frequency changes -> exposing 'bad' alleles > 'bad' alleles multiply in frequency 1 13/03/2013 -Allee Effects: Population falls below a certain size, mating decreases -Colonial breeders: get into a group to breed -If the population size is low, the group will not exist -It is the presence of this group that initiates mating behaviour -No group means no mating Demographic effects of declining populations Which matters m...
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