ANT 1 Lecture Notes - Lecture 5: Phenylalanine, Human Height, Twin Study
Document Summary
+/+ tall | -/+ medium | -/- short. Assume p = q = 0. 5, apply hardy-weinberg. Produces normal distribution; add independent effects = normal distribution. Possible explanation for some rare diseases or impairments. Evidence that additive effects characterize height variation. Bad job at predicting human height: many more loci are involved. These only explain ~27% of variation in height. Height is highly heritable in most populations. Heritability = variation accounted by genotype / total variation. Monozygotic twins share all of their genes (some variation due to mutation) Dizygotic twins share only half their genes. Adoptions = different environments = study of environmental influence. 60 - 80% due to genetic variation/heritability rather than environment. Imagine we gave everyone the same amount of food throughout life. Environmental conditions play less of a role. Natural selection can act on discrete (on/off, wet/dry) or continuous phenotypes. Freq (u) = p = 0. 4 so. Uu = 0. 16 | uu = 0. 36 | uu = 0. 48.
