Expectations of spread (S) matings in pigeons, Columba livia

Breeding Expectations for Spread by Frank Mosca

Ash-red spread Spread (wild-type) Spread + rubella ee + pale-NOT Spread (Does anyone have a good picture of a brown spread I can use? The only one I have is grizzle.) Spread is the genetic factor which turns blue bars & checks into blacks; brown bars & checks into self browns; ash-red bars & checks into "lavenders", "barless mealies", or "strawberries". It is NOT the same factor as recessive red (e) which creates red selfs. Recessive red is epistatic to Spread. Spread is not sex-linked so a hen may be heterozygous for it. This is why you won't see that (.) symbol I use to indicate the sex-linked chromosome. Spread is on a totally different chromosome than that and a hen has two sides to that as she does to all others except the sex chromosome. When you add other modifiers to spread, the lid is off and you can get some of the most beautiful expressions of color available in pigeons. See the Spread rubella bird above or the Lavender Lahore below.

Spread milky lahore

Punnett Squares list the cock pigeon's genetic contribution down the left side and the hen pigeon's across the top. The expected youngsters are shown at the intersections of the square. There is an example on how to read these squares toward the bottom of the page.

Homozygous Spread cock ( S//S) X Wild-type hen (+//+) (In this case, wild-type means a bird without spread - a blue bar. The homozygous Spread is a black.)

	+	+
S	S+	S+
S	S+	S+

Expectations are: 100 % heterozygous Spread youngsters (all young of either sex are spread - in this case that means black)

Heterozygous Spread cock ( S//+) X Wild-type hen (+//+)

	+	+
S	S+	S+
+	++	++

Expectations are: 50% heterozygous Spread cocks and/or hens 50% homozygous wild-type cocks and/or hens

Heterozygous Spread cock ( S//+) X heterozygous Spread hen (S//+)

	S	+
S	SS	S+
+	S+	++

Expectations are: 25% homozygous Spread cocks and/or hens 50% heterozygous Spread cocks and/or hens 25% homozygous wild-type cocks and/or hens

Homozygous Spread cock ( S//S) X heterozygous Spread hen (S//+)

	S	+
S	SS	S+
S	SS	S+

Expectations are: 50% homozygous Spread cocks and/or hens 50% heterozygous Spread cocks and/or hens

Homozygous Wild-type cock (+//+) X Homozygous spread hen ( S//S)

	S	S
+	S+	S+
+	S+	S+

Expectations are: 50% heterozygous Spread cocks and/or hens 50% heterozygous Spread cocks and/or hens Notice that these expected results are identical to those in the second box. That's because Spread is not sex-linked.

Example For practice in reading a Punnett Square, let's take a Homozygous Ash-red Cock (B^A//B^A) X a wild-type Hen (+.) (In this case, wild-type means any blue/black hen, pattern immaterial)

	+	.
B^A	B^A//+	B^A.
B^A	B^A//+	B^A.

The cock's contribution is read top to bottom on the left side of the table. In this case, B^Aand B^AThe hen's is read right to left across the top of the table. In this case, + and .
So how do we figure the youngsters? Easy. Fill in the cock's contribution on each line across. On the first line it would be B^A. Fill in the hen's contribution going down. So in the first square we have B^A//+ In the next square to the right, we have B^A. Thus in this example, the first bird is an ash-red cock carrying wild-type (blue) and the second is an ash-red hen carrying nothing, and so on.
I am using a dot (.) to indicate the small tag a hen has in addition to her single sex chromosome. One more thing. I always refer to wild-type. If I'm discussing dilution, it means the wild-type condition to that particular gene, thus intense coloration. If I'm discussing Indigo, it means the wild-type condition to that, thus non-indigo. If I'm discussing pearl eyes, it means the wild-type condition to that, thus orange eyes, etc.
Therefore, youngsters bred from this mating can be:

50% heterozygous ash-red cocks. (B^A//+) Many will have black splotches.

50% hemizygous ash-red hens B^A/.

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