Home » Plants & Animals » Rats and Rodents » Rat Genetics 101 - Page 2

Rat Genetics 101 - Page 2

© Karen Yang

If the pet store that Pinky's in leaves the babies together too long, and two of the little ones mate, we'll end up with babies that have a mixture of both eye colors. Here's where the famous Punnett square comes in handy. Each egg of the female rat contains either a P or a p, and each sperm from the male contains either a P or a p, so we end up with the following:

x	P from Dad	p from Dad
P from Mom	PP	Pp
p from Mom	Pp	pp

As you can see from the chart, half the babies will be like mom and dad, heterozygous black-eyed rats, Pp. One fourth of the babies will be homozygous dominant black-eyed rats, PP, and one fourth will be homozygous recessive pink-eyed rats, pp. So half of the litter will have black eyes and carry the pink eye recessive trait, one fourth will have black eyes with no recessive pink-eyed trait, and one fourth will have pink eyes. (In reality, the numbers don't always work out this neatly, but they usually do come pretty close.)

Note: The pink eye gene does more than change the pigment in the rats' eyes. It also causes a dilution of fur color as well. A rat who otherwise would be Black will turn to Champagne if pp, for example!

Some of the gene information in this article taken from Nick Mays' The Proper Care of Fancy Rats

For more info:

Myomorpha: http://www.rodentfancy.com/myomorpha/fin...
Ratmap: http://ratmap.gen.gu.se/
What is Inheritance?: http://gslc.genetics.utah.edu/basic/conc...

The copyright of the article Rat Genetics 101 - Page 2 in Rats and Rodents is owned by . Permission to republish Rat Genetics 101 - Page 2 in print or online must be granted by the author in writing.