I. What are pedigrees?
Charts used to study the inheritance of a
trait within a family or population.
II. Uses
A.
Commonly used in dealing with breeds of animals (cats, dogs, horses,
cattle . . .)
B. Useful
for zoos to prevent inbreeding within the zoo populations.
C. Especially
useful in determining which members of a family may have a disease.
D. Useful
in determining the odds that a couple will have a child with a birth defect.
E. Can
use to deduce genotypes of each family member.
III. Symbols that you will see when making
a pedigree.
1. Squares = males
2. Circles =
females
3. Shaded circles
and squares = individuals affected by the studied condition.
4. White or clear
squares and circles = unaffected individuals.
5. Half shaded
circles or squares = known heterozygous individuals
6. A straight
horizontal line between a male and a female represents a “marriage” or mating
line. A vertical line descending from a marriage line
represents the offspring of the
parents.
7. A circle or square with a line through it
represents a deceased individual
8. A marriage line that has a line through it
represents a divorce.
9. Rows of individuals represent generations and
are represented by Roman Numerals.
10. Each individual is numbered from left to
right in each row. #1 is the oldest
child
in each row and will
always be the first square or circle in the row. The next oldest
individual will
be #2 in the row. Etc. This rule applies to siblings.