If you were given a bunch of plants with a smooth continuous distribution of phenotypes, how would you determine if there was a genetic basis to the variation? Simply select individuals from the distribution with distinct phenotypes, breed them (=parents) and compare the phenotypes of these parents to that of their offspring. If the mean phenotype of offspring was close to the mean of the parents this would be evidence for a genetic basis for the phenotype and the trait would be identified as heritable . If on the other hand, the offspring produced from two "high" parents were extremely variable in phenotype and offspring produced from two "low" parents were extremely variable there would be a weak genetic component to the trait. The heritability in a "broad" sense can be expressed as the proportion of the total phenotypic variance that has a genetic component: h 2 B = V G /V P . (see figures 9.5 pg. 231; 9.6 pg. 237).
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This note was uploaded on 11/05/2011 for the course BIOLOGY MCB2010 taught by Professor Jessicadigirolamo during the Fall '10 term at Broward College.