The booklet that comes with AZ calls back crossing "return breeding". AZ's definition states that return breeding is "the process of crossing offspring with the parents, in order to concentrate particular genetic characteristics and stabilize the genetic line." I use the term "back crossing" because I am reaching back to a parent (usually a male but not all the time) to mate with a daughter, granddaughter, great granddaughter (you get the picture) for several generations. This practice would only be possible in real life for only as many generations as the original "dad" was alive and capable of breeding. Using TransWarp, the breeder of AZ guppies can use the original "dad" indefinitely. This is not genetics, but manipulation of AZ's programming by the use of a "cheat".
We have used selected back crosses with caution in several of the previous pools. If the "dad" guppy you are using is homozygous for all the traits exhibited by his phenotype you can use him to quickly stabilize a strain in as few as five generations. If the "dad" guppy you have selected is heterozygous for one or more traits (one or more tail colors and/or one or more tail patterns) his sons, grandsons, great grandsons (so on and so forth) can begin to exhibit a wide variety of phenotypes. And, the possibilities take on an added dimension when you consider the female is also heterozygous and is selected at random from each generation. I say, "things can get real goofy". All sorts of phenotypes can start to show up when the breeding tank opens to reveal the 90-day-old males. I have a mental image of Mother AZ saying to herself, "Just what is this pseudo geek trying to make me produce? Here fool, see anything here that you like? Hey, how `bout this guy? Enough already!"
Looking over the .fsh files we have generated up to this point I decided to return to the ill-fated "quad cobra chase" folder and use the F1 generation from that cross in this demonstration. I know this specific F1 is fully loaded with many of Mother AZ's heterozygous tricks and I want to exploit this situation.
Once again, here are the F1 males in this family group.
I decide to use the "leopard multi orange" male to father successive generations just to see what AZ will reveal to us. I have no idea what might happen. What I am looking for is something "new and wonderful". Just what phenotype will qualify as "new and wonderful" remains to be seen. This technique often leads nowhere.
Enough talk! Let's get started and see what happens.
Here are the males in the F2 generation.
Nothing special here. I select a female at random (usually the first one in the file) and mate her with her dad.
Here are the males produced in the F3 generation.
I've seen all those guys before. I select a female at random and mate her with her granddad to produce the F4 generation.
Here are the males produced in the F4 generation.
Here we see the guys on the left have a pale cornflower blue color in the dorsal instead of the white rectangle we usually see. Interesting development, but not "new and wonderful" IMHO. OK, now what do we do for the next generation? That's correct. Select a female at random and mate her with her great granddad to produce the F5 generation.
Here are the males of the F5 generation.
This is boring so far. Wonder what would happen if we selected a female from this batch and mated her with her great great granddad to produce the F6 generation. (I've been known to do this for 15 - 20 generations.)
Here are the males produced in the F6 generation.
Wow, what a beautiful turquoise color. I love that color! I think I will name this color "wow" until I give it an official color label later on. We also see the improved dorsal trait in one of the males. It is a shame AZ has chosen to scar the leopard phenotypes with that darn white rectangle in the dorsal.
OK, AZ has performed as hoped for and produced something "new and wonderful" for us to work with. Let's continue to use the same technique of back crossing and see where this "wow" male will lead us. We mate this guy with one of his sisters to produce a new F1 generation but for us it is the F7 generation. (Don't try to follow that. I just need to keep each generation at the top of my "items" folder so I know where I am at in this breeding session.)
Mr. Wow and one of his sisters produced this F7 generation.
Here we see a tiger multi male (#4) and several more of Mr. Wow's phenotype (#1) and two additional leopard multi colors (#2 and 3). We reach back and haul Mr. Wow out of his file and make him do the nasty with one of his daughters to produce the F8 (for us, F2 for them) generation.
Here are the males in this F8 generation.
AZ is running low on genetic possibilities for us to see. We now see this "wow" color in tiger multi and leopard multi. Keeping with the plan, we haul Mr. Wow out of his .fsh file and force him to do the deed with one of his granddaughters to produce the next generation.
Here are the males in the F9 generation.
We still see the tiger multi phenotype. Is this back cross going to produce a homozygous leopard multi strain or will things get goofy again? In order to find out we haul Mr. Wow out of his file again and match him up with one of his great granddaughters to produce the next generation.
Here are the males of the F10 generation.
Let me tell you that this is one beautiful batch of guppy brothers swimming around in the display tank posing for their picture. However, in reality this generation is actually just the F4 generation as far as this phenotype is concerned. Returning to the F6 .fsh file, we haul Mr. Wow out and oblige him and one of his great great granddaughters to produce the next generation. (This is usually where my wife starts to call me a "weird little old man".)
Here are the males produced in the F11 generation.
We still have tiger multi in this gene pool. This is not an unexpected development. Let's do it again. Who will be the father? Mr. Wow! Who will be the mother? One of his great great great granddaughters of course. Makes sense to me.
Here are the males in the F12 generation.
|
