OK, let's see what we can do with the two strains we have stabilized. Our goal is to create a strain of "Tuxedo Christmas Reds". We have strains of Red Tail "Christmas Reds" and "Tuxedo Pearl Grays" with which to work. We know that the tuxedo phenotype is sex-linked and passed on by the female (I read it somewhere) so the female will come from the tuxedo pearl gray strain. I had trouble stabilizing the Christmas Red strain. I suspect a recessive red orange gene is hidden in that gene pool. If the F1 males all look alike I will continue with the cross. If the F1 males exhibit more than three different phenotypes I will have to go back and do some more work with the Christmas Red strain. Let's put a pair into the tank and see what we get. Crossing two stabilized strains to create a mixed hybrid is referred to as out-crossing (or out-breeding).
Here are the males produced in the F1 generation.
ALL RIGHT, they all look alike. The clear multi phenotype is to be expected. Happens all the time. It's like AZ is telling me that I am back to square one with a new gene pool to sort out. I'll save the entire brood to a file labeled "0 F1 Pearl Tux x Christmas Red" and see what the F2 looks like. Since all the males are identical a random pair was selected to produce this F2 generation (you can select for VCP scores it you like).
OK! Something to work with. One of the males is just what I was hoping to see. Ain't he purdy!
Non-tuxedo males are to be expected and I know that I will have to now look for the "right tuxedo sister" to produce the F3 generation. We cull the two non-tux males and save the Tuxedo Red Christmas male and all of his sisters to a file labeled "0 0 F2 male w females". I select the first female in the file and mate her with her brother now labeled "Christmas Red Male". Here are the males produced in the F3 generation.
We have only one male in this brood that looks like our template phenotype. At this point, for the purpose of this breeding example, I decided to use a breeding technique called "back-crossing". This technique will quickly fix the tuxedo trait into a strain in a generation or two. If the F2 male is homozygous for "Christmas Red" and clear tail pattern this approach will eliminate having to search for the right tuxedo sister. If the F2 male is heterozygous for color or tail pattern this approach will not work. I will use the F2 male to father the next couple of broods (concentrating his characteristics).
Back-crossing is tricky. If the male has a recessive (or heterozygous) gene hidden somewhere, back crossing will quickly reveal this gene (or pair of genes) in a generation or two. Taking a back-cross out too many generations can result in all sorts of phenotypes showing up. This is fun to do when you are searching for something "new and exciting". However, when you are trying to stabilize a strain you gotta know when to discontinue the back-crossing and switch to inbreeding (brother/sister or sibling/sibling) again to produce the next generation.
I rename the F3 file "0 0 0 F3 fathered by F2 male" so I can remember when I started using the F3 dad. (I keep no written notes. Call me crazy. I try to put everything I need to remember in the file name.) I select a female from the F3 file and haul out the F2 male from his file to produce the next generation. After he has done the deed I save him to his own file "0 0 dad from F2 to use in back-crosses" so I can easily find him again.
Here are the males produced by this incestuous union.
Three that look like granddad and three that look like great great granddad. Since this is the first generation produced by a back-cross, I don't expect to see good results for another generation or two. All I need from this brood is a female to use to produce the F5 generation when mated with the F2 dad. Here are the F5 males produced by this even more incestuous union of the F2 male and a female from the F4.
Well, well, well. There's that darn red orange color again (last seen in some early generations of the Christmas Red strain). Guess my suspicions were correct. There is a hidden recessive red orange gene in that Christmas Red strain. Time to conclude the back-crossing and switch to sibling matings for the next generation.
I select a pair to produce the F6 generation. (The back-cross may have been a bad idea. Will I be able to eliminate the red orange gene from the gene pool ? I may have to go back to the F2 and start over. Oh well, let's see what happens.) I crossed every female with every male and the red orange phenotype appeared in every batch. Not to worry, I'm just at the F6. Not bad really.
I selected this batch to be the F6.
Wonder if I will find a pair from this batch to produce a decent F7 generation? Boy, talk about searching for the "right sister". I also had to find the "right brother" to finally produce this F7 brood. I tried three different males before the third brother and a sister produced this batch of males.
Since Mother AZ gave me only four males in this batch, this may be just an illusion, but it is looking good at this point. The first pair selected produced this F8 batch of males.
Looks promising. I think we just might be almost there. Four or five more generations will let me know.
I took this strain out six generations to the F14. I saved a pair from each new generation into the F8 file (I've got lots of shortcuts up my sleeve) until I felt that the strain was fixed. Here is the F14 generation, now proudly labeled, "Tux Christmas Red stock".
Here is what my "Items" folder looks like after creating this strain. You can see the complete record of all the saved crosses made to create this strain. All the other broods produced in the search were flushed with each water change.
Now where do we want to go from here? In order to create a strain of "Tux Tiger Christmas Reds" we need to stabilize a strain of Yellow Mosaic Tigers first. Some people say the Mosaics look like just a bunch of dots, lines and squiggles. Guess I'll haul out a pair and give them a look. One strain of stabilized Yellow Mosaic Tigers or dots or squiggles coming up.
|
