200 "genetic manipulation of a species" "How much genetic variation is there Historical debate Classical school held that there was very little genetic variation, most individuals were homozygous fora "wild-type" allele. Rare heterozygous loci due to recurrent mutation natural selection purges populations of their "load" of mutations. Balance school held that many loci will be heterozy- gous in natural populations and heterozygotes maintained by "balancing selection" (het- erozygote advantage. Selection thus plays a role in maintaining variation. How do we measure variation To show that there is a genetic basis to a continuously varying character one can study 1) resemblance among relatives: look at the offspring of individuals from parents indifferent parts of the distribution can estimate heritability more later. 2) artificial selection: pigeons and dogs show that there is variation present does not tell how much variation" -- Reference http://biomed.brown.edu/Courses/BIO48/5.Geno.Pheno.HTML (back to 200)
