Intermediate Inheritance/alleles SOMETIMES it is possible for genes to work together to create new phenotypes that are neither Dominant nor Recessive

Intermediate Inheritance/alleles These traits are considered Intermediate Inheritance, and are the result of gene-blending by Co-dominance.

Intermediate Inheritance/alleles Co-dominance means that sometimes there are more than 1 Dominant Trait. If you receive 2 co- dominant alleles, they will blend together to create a new phenotype.

Intermediate Inheritance/alleles Example: Mice hair color genes have a co-dominance with Black and White—meaning that BOTH black and white are dominant alleles. Brown is the recessive allele in mice.

Intermediate Inheritance/alleles If a mouse’s genotype is heterozygous Black and White, these co-dominant genes will blend together and create a mouse with a grey phenotype.

Intermediate Inheritance/alleles In Mice, the grey phenotype is considered an Intermediate Trait because its phenotype is neither truly dominant or recessive, but rather a blend.

Intermediate Inheritance/alleles Some flowers are Co-dominant Red and White, and if cross-pollinated will produce heterozygous, codominant Pink offspring. If the pink flowers are crossed, then the offspring will be either Red or White again.

Intermediate Inheritance/alleles Other Intermediate examples: (in humans) Red Hair (blending of pheomelanin into other hair pigment) Green /Hazel Eyes (blending of melanin into other pigments)

Intermediate Inheritance examples 2 Skin color (blending of various dark/light pigments) Blood type ( A and B types are both Dominant type O is recessive) AB blood type)

Intermediate Inheritance—How it works Ex: Andalusian Chickens come in Black, White, or ‘Blue’. White and Black Colors are co- dominant with each other.

Intermediate Inheritance—How it works Blue is the intermediate trait, created when a Black Color allele and a White color allele are combined and blended.

Intermediate Inheritance Genotype When writing these Intermediate alleles, the “C” for Color is used. With the “C”, a superscript “W” or “B” is used to show which Intermediate alleles it has.

Intermediate Inheritance—How it works C w C w = White C B C B = Black C B C w = Blue chicken Tasty Chicken…

Intermediate Inheritance Punnett Squares A Punnett Square testcross is the same as a Mono- hybrid cross, but would place each intermediate allele in each section of the diagram.

Intermediate Test-cross (punnett square) Mr. Vogel has Blood Type B. There is no type O in his family, So he is homozygous Type B Mrs. Vogel is Type A, with some type O (recessive allele) so her genotype is heterozygous A and O Both A and B are co-dominant alleles, but O type is recessive. What are the possible outcomes of their children's’ blood type?

Intermediate Test-cross (punnett square) Step 1: make the square

Intermediate Test-cross (punnett square) Step 2: create the genotypes: T will be used for blood Type Mr. V is homozygous B—so the genotype is T B T B

Intermediate Test-cross (punnett square) Step 2: create the genotypes: Mrs. V. is Heterozygous A and recessive O, so the genotype is T A t. (t = the recessive blood type allele)

Intermediate Test-cross (punnett square) Step 3: add the genes to the square, and do the test- cross, like normal

Intermediate Test-cross (punnett square) Note: if you see genotypes with both dominant traits, then they will be blended.

Intermediate Test-cross (punnett square) So, the outcomes of blood types are… _____% A _____% AB _____% B______% O

Intermediate Test-cross 2 (punnett square) Snapdragons are co-dominant red and white. If these genes are combined, then the produce pink flowers. What % of the offspring would white if 2 pink parents are mated?

Intermediate Test-cross 2 (punnett square) Step 1 –square Step 2: create genotypes: --C for Color is used. --Pink is a blend of red and white so a pink’s genotype must be C R C W.

Intermediate Test-cross 2 (punnett square) Step 3: add the genes to the square and do the test-cross. According to the data ____ of the offspring will be white, and _____ will be red.

Polygenic Inheritance  Many traits are NOT determined by 1 set of 2 alleles alone.  Some phenotypes, like tallness, and eye appearance are considered Polygenic, or created from more than 1 set of genes.

Polygenic Inheritance  Ex: Height  A person’s height may be determined by multiple characteristics:  Length of leg-bones  Length of torso/vertebrate  Length of neck.

Polygenic Inheritance  Since these characteristics all have their own Genotype, and are all combined to make a person’s total height, Height would be a Polygenic trait.

Polygenic Inheritance and the environment  Many traits may be affected by their environments as well.

Polygenic Inheritance and the environment  Ex 1: a person’s polygenic genotype may say that this person should be very tall, but a lack of proper nutrition may keep the person shorter than they could be.

Polygenic Inheritance and the environment  Ex 2: A person may have a genotype for dark hair color, but if they spend a lot of time outside in the sun, then the hair color may become lighter than the Genotype said it should be. (and makes skin darker)

Polygenic Inheritance and the environment Different Hormones produced by different genders will also have an effect on the POTENTIAL of certain traits, like facial/body hair, muscle mass and body shape.