4.3 Selective Breeding

Pages 140-143

Selective Breeding

• Choosing to breed plants and animals because they have desirable characteristics

Inbreeding

• Mating closely related individuals to preserve characteristics

Hybridization

• Dogs

Hybridization

• fruit

Hybridization

• Honey crisp apples (parent type unknown)

Hybridization

• Canola from rapeseed(used to have a bad taste)

Hybridization

• Marquis wheat from Red Fife and Red Calcutta

Heirloom

Pedigree

A diagram of an individual’s ancestors used to analyze the Mendelian inheritance of a certain trait.

Pedigree

• also used for selective breeding of plants and animals.

Family Tree

Freckles

The allele for freckles, F, is dominant.

Image: genetics.thetec.org

Marfan’s Syndrome

Pedigree

Example:

Image: saburchill.com

Legend

Symbols and their meaning: image: uic.org

Guidelines:

Roman numerals signify generationsArabic numerals identify individuals within generations.Birth order is left to right

Sex Linkage-Following the X and Y chromosome

Autosomal inheritance is found on the autosome

Sex-linked genes are found on the X chromosome

X-linked

Females must inherit 2 recessive alleles on the X-chromosomes to express the trait.

Males only need to inherit one X chromosome from their mothers to express the trait. The Y chromosome cannot mask the trait.

hemophilia

Carried on the X chromosome image: torresbioclan.pbworks.com

hemophiliaImage: torresbioclan.pbworks.com

Punnett square for hemophilia

Father is a carrier. Image: macalester.edu

Red-green colour blindness

X-linked traits

The sexes exhibit different phenotypic ratios. More males than females will express the

recessive phenotype. More females are carriers of the recessive X-

linked alleles.Examples: red-green colour blindness, hemophilia, and male-pattern baldness

Y-linked traits

Traits are controlled by a single allele passed on from fathers to sons on the Y chromosome.