3.22: Understand that Most Phenotypic Features are the Result of Polygenic Inheritance Rather than Single Genes

MOST PHENOTYPIC FEATURES ARE CAUSED BY POLYGENIC INHERITANCE:

• As most characteristics in an Organism are controlled by more than one Gene, these Organisms are described as Polygenic
• Polygenic characteristics involves Phenotypes that can express a wide range of combinations in features

EXAMPLE: EYE COLOUR

• B is a Dominant Allele for Brown Eyes

• b is a Recessive Allele for Blue Eyes

EYE COLOUR OF OFFSPRING
PHENOTYPES OF PARENTS	Brown Eyes                         Brown Eyes             (Heterozygous)                    (Heterozygous)
GENOTYPES OF PARENTS	Bb                                       Bb
GAMETES
GENOTYPES OF OFFSPRING
PHENOTYPES OF OFFSPRING
RATIO	Brown Eyes   =    ¾               Blue Eyes      =    ¼