PATTERNS OF HEREDITYCHP. 10

INCOMPLETE DOMINANCE

• An individual displays a trait that is intermediate between the two parents.

• Neither allele is completely dominant

• Ex: red vs. white = pink

• Hair texture: straight vs. curly = wavy

CODOMINANCE

• Equal expression of both alleles

• Ex: Type AB blood

POLYGENIC INHERITANCE• Inheritance pattern of a trait

that is controlled by 2 or more genes

• Can be on the same chromosome or different ones

• Ex: eye color, skin color, height

ENVIRONMENTAL INFLUENCES• Internal environment- age,

gender can affect gene function, hormones, structural differences

• External environment- temperature, nutrition, light, chemicals, infection

SELECTIVE BREEDING• Produces organisms with

desired traits (dogs, horses)

• Eliminate undesired traits by inbreeding (mating closely related individuals), keeps a pure line

• Testcross- cross of an individual of unknown genotype with an individual of known genotype

Carrier- heterozygous, looks like a homozygous dominant individual

HYBRIDS• Mating of closely related

species

• The offspring are sterile

• Rarely happens in nature

• Ex: Liger (lion x tiger)

Wolfdog Wolphin

Zeedonkey Grolar bear

CAMA