Partridge Birds’ Genetics Family Tree
Name & Hr:
An Exercise in Traditional Genetics
In this exercise, you will need to predict the phenotypes and
genotypes of the un-hatched baby birds. To do so, you will
have to use your skills of observation, your understanding of
Punnett Squares, and your knowledge of dominance,
recessiveness, incomplete dominance, and co-dominance.
The traits shown in this picture are as follows:
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Body color
Wing color (co-dominant trait)
Beak color
Beak size
Feet size
Head feather (incomplete dominance)
Mating pairs of birds are denoted by a dotted line running between them. This dotted line forms a box – inside of this
box are the offspring of that pair. In this case, the four birds at the top of the diagram are the grandparents of the eggs.
The two individuals in the middle directly above the eggs (connected with a dotted line) are the parents.
To begin, determine which traits are dominant and which are recessive. You best bet is to then figure out the genotypes
of the parents for each trait, and then figure out the genotypes (and subsequent phenotypes) of the eggs.
If you recall, dominant traits overshadow recessive traits if they are together (heterozygous, e.g. Bb). This does not
mean that their offspring cannot express these traits! For example, the four offspring of the Blue and Yellow pair on the
left all have yellow beaks except for one, indicating that both parents carried the recessive traits for the orange beak.
Some traits are not completely recessive or dominant. One trait is co-dominant. In the same way that co-captains of a
football team are both equally captain, co-dominant traits are when two dominant traits are both equally expressed. In
this case, we see that Wing Color is a co-dominant trait. Some birds have blue wings, some have yellow wings, and
some have blue AND yellow wings.
Some traits are incompletely dominant. In this case, they blend. One trait here is incompletely dominant as well (the
size of the head feather). In some cases, the head feather is large, in some cases the head feather is shorter, and in
some cases, the head feather does not exist at all. The large feather would be homozygous dominant, the medium
feather would be heterozygous, and the non-feather would be homozygous recessive.
You may work together, but each person must complete their own sheet. The genetics PowerPoint is available online
from my website on the Weekly Schedule page. The partridge diagram is also available there.
Those who correctly identify the genotypes and phenotypes of the eggs and can explain how they came to this will
receive one point of extra credit on their final class grade. YOU MUST show your work. Keep in mind that no one, not
even the teachers and substitute teacher, know the answer. Mr. Kohn is the only one with the answer, and he’s gone!
You will need to use your scientific training to figure this one out. Work together and use what you know to determine
the answer. Ask yourself “How do I know I am not wrong?”
Show your work here. Attach separate sheets if needed.
Egg Genotype Possibilities and Ratios
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Body color
Wing color (co-dominant trait)
Beak color
Beak size
Feet size
Head feather (incomplete dominance)
Parent Genotypes and Phenotypes
-
Body color
Wing color (co-dominant trait)
Beak color
Beak size
Feet size
Head feather (incomplete dominance)