Transcript Dihybridization and Domestication

History of the Munchkin
• First noted in 1940’s
during London Blitz
• Cat reappears in
Stalingrad in 1953
• Pregnant cat found in
Rayville LA in 1983
Munchkin Genetics
• Short bone structure
in legs caused by a
dominant allele
• What is the risk of
breeding munchkin
cats of unknown
genotype?
How Is Heterozygosity A Problem
In The Domestication of Animals?
Puggles & Labradoodles
Dihybridization
• The probability of inheriting two traits
may be determined using a 16 box
Punnett square.
• Each parent makes 4 possible gamete
combinations from the two
homologous pairs associated with the
traits
• As before, gametes must contain only
one chromosome from each
homologous pair
• Homologous pairs are reunited in the
16 possible zygotes
Independent Assortment and
Formation of Gametes
Phenotypic Ratios
• Phenotypic:
• Dom1Dom2: Dom1Rec2: Rec1Dom2: Rec1Rec2
Genotypic Outcomes
Sample Dihybridization
• Assume that the trait of smooth peas is
dominant (S) relative to the trait of
wrinkled peas (s)
• Assume that the trait of yellow peas (Y) is
dominant to the trait of green (y)
• What proportion of the offspring from
the cross of two true dihybrid parents
(heterozygous for both traits) will
belong to each of the four phenotypic
categories?