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Ok, so you've read all the
previous pages and feel like you understand it all (more or less) but you
still don't know how to apply it to the problem in hand. In other words, you
still don't know how to tell what you'll get when you breed your Amel Motley
Cornsnake, het for Caramel to your Butter Motley Cornsnake. Well, you are
not alone, and you are not stupid.
While all of this genetics stuff may seem complicated, it's really no harder than anything else
you've learned. Take mathematics for instance. Once you learned the basic
rules of addition, and did enough practice to let it all sink in, you could
add any two numbers together - no matter how large and complicated seeming.
Genetics is no different.
Here's how to do it:
- Step One - To predict any outcome from any breeding, you must
understand what traits are actually present in the parents. To proceed, you
MUST research the trade name you are familiar with (here Amel Motley, het
Caramel and Butter Motley) to find out what traits these morphs are actually
composed of.
In our example above, you must forget that one parent is an Amel Motley Cornsnake, het for
Caramel and the other is a Butter Motley Cornsnake. Names like that are
meaningless, genetically speaking.
Instead, you must learn
to view them as a Cornsnake that is homozygous for Amelanism, homozygous for
Motley, and heterozygous for Caramel and a Cornsnake that is homozygous for
Amelanism, homozygous for Motley, and homozygous for Caramel.
Do this for every locus containing a mutated allele in either parent (in this case three
alleles at three loci total). While
you are at it, learn the commonly used genetic connotations (abbreviations)
in use for each trait.
Parent 2) Amel Motley, het Caramel Cornsnake
(aaaa·mmmm·Ca+cac)
Amelanism, homozygous - abbreviated as: aaaa
Motley, homozygous - abbreviated as: mmmm
Caramel, heterozygous - abbreviated as: Ca+cac
Parent 2) Butter Motley Cornsnake
(aaaa·mmmm·caccac) Amelanism, homozygous
- abbreviated as: aaaa Motley, homozygous
- abbreviated as:
mmmm
Caramel, homozygous - abbreviated as:
caccac
- Step Two - You must treat each Locus separately when predicting
the outcome for the breeding. In our example, we have three alleles residing at
three separate loci - so we'll be doing three separate calculations, one for each
loci.
For our example, we'll simply list each locus and place the alleles present
there from each parent side-by-side, like this:
At the
Amel Locus ( A),
we have:
aa aa
At the Motley Locus (M),
we have:
mm mm
At the
Caramel Locus (Ca),
we have:
+c cc
Then we'll use our simplified FOIL technique to tabulate the results at each
locus. We could create a Punnett Square for each trait, but FOIL is quicker
once learned. FOIL is an anachronism for First pair, Outside
pair, Inside pair, and Last pair. Remember, one allele is
passed from each parent and FOIL will help us quickly determine the four
possible combinations for each locus. It works like this, and here we've
highlighted each pair from the first locus in red for you:
Amel Locus (A)
aa
aa
First Pair
Amel Locus (A)
aa aa
Outside Pair
Amel Locus (A)
aa aa
Inside Pair
Amel Locus (A)
aa
aa
Last Pair
In this example, we have:
aa,
aa,
aa,
aa.
Now we'll repeat this for the next locus:
Motley Locus (M)
mm mm
First Pair
Motley Locus (M)
mm
mm
Outside Pair
Motley Locus (M)
mm mm
Inside Pair
Motley Locus (M)
mm mm
Last Pair
In this example, we have:
mm,
mm,
mm,
mm.
Now we'll repeat this for the last locus:
Caramel Locus (Ca)
+c cc
First Pair
Caramel Locus (Ca)
+c
cc
Outside Pair
Caramel Locus (Ca)
+c cc
Inside Pair
Caramel Locus (Ca)
+c cc
Last Pair
In this example, we have:
+c,
+c,
cc,
cc.
Step Three - Now we combine the results of the first two alleles
(Amel and Anery) by using a simple grid, much like that of the Punnett
Square.
First, place the results of FOIL for the first allele along the left side:
Next, place the results of FOIL for the second allele along the top:
Finally, fill in the grid with the results:
| |
mm |
mm |
mm |
mm |
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aa |
aamm |
aamm |
aamm |
aamm |
|
aa |
aamm |
aamm |
aamm |
aamm |
|
aa |
aamm |
aamm |
aamm |
aamm |
|
aa |
aamm |
aamm |
aamm |
aamm |
To add in the results of the third allele, we now create another grid. This
time, place the results of the first grid along the left side:
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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aamm |
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Next, place the results of FOIL for the third allele along the top. Notice
that in this example, all results along the left side are the same.
Therefore, we can simplify our task by combining the results into one row.
Not all breedings will allow your to do this, but most will to at least some degree.
Now our grid should look like this:
Finally, fill in the grid with the results:
| |
+c |
+c |
cc |
cc |
| aamm |
aamm+c |
aamm+c |
aammcc |
aammcc |
Now, we can see the results of our breeding!
We've produced two types:
aamm+c
and
aammcc.
We can also see these are produced
in a half and half ratio.
By reinserting the connotations for each locus, we get:
aaaammmmCa+cac
and
aaaammmmcaccac
In other words, these
two types are: Cornsnakes that are homozygous for Amel, homozygous for
Motley, and heterozygous for Caramel and Cornsnakes that are homozygous for
Amel, homozygous for Motley, and homozygous for Caramel.
Or if you insist on going back to those confusing but
all too familiar trade names,
we've produced a clutch containing Amel motleys, het for Caramel and Butter Motleys. Not bad for a day's work!
Ok, so I've showed you how to do it. Let me guess you still have a gazillion
questions, right? Let's try to answer some of the common ones here:
Q: I have a total of five traits in my breeding, how do I figure this
when your example only has three?
A: No problem. Follow along exactly as I showed you. When you get to
the end, create yet another grid - placing the results you just obtained in
the left hand column just as before. Now FOIL allele number four and place
it at the top. Figure out the results and you will now have all the
combinations possible for four alleles. Repeat the whole thing again for
trait number five....six...seven...whatever.
Q: My snake contains a trait that's incomplete dominant, how does that affect
the outcome?
A: It doesn't. Such traits are still passed along in the exact same
fashion, and can still be predicted 100% accurately using the method we just
showed you. The only thing different about such traits is that specimens
heterozygous for the trait will be visibly distinguishable from normals.
Specimens homozygous for the trait will have still another appearance,
usually even more drastically different from normal.
Q: My snake contains a trait that I'm told is a selected trait, how
does that affect the outcome?
A: Well, the truth is that selected (polygenic) traits just don't
work this way. Well, actually they do, but they are composed of perhaps
dozens of alleles, each of which contribute to the overall appearance, many
of which cannot be identified by themselves. Thus the results cannot be
accurately predicted. Go back a page to Genetics
501 and review the information there on polygenic traits until it sinks
in. But remember, you can still use this method to predict the outcome of
crosses to typical mutations, you'll just have to sort through the babies
for a few generations to fully regain the desired appearance.
Q: Why didn't my clutch hatch out to match the predictions?
A: While this method does predict the correct ratios and types of
offspring that will result, mother nature still has her quirks. These
predictions are just averages, and it can take a LOT of hatchings to make
the numbers work out. Just because one in sixteen eggs is supposed to be a
rare yellow-spotted stump-whumper, doesn't mean egg number sixteen is going
to be one. In fact, you may go hundreds of hatchlings before a dozen of them
suddenly appear in one clutch. That happens to us quite often, and of course
the opposite often happens as well, but never to us. I'll put up a page on
Murphy's Law if you really can't understand how that can be. There are also
other potential factors which can account for this, such as trait linkage,
sex linkage and so forth. Go back to
Genetics 501 to learn more
about these subjects.
Q: My clutch produced types of specimens not included the predictions,
what happened?
A: Well, in today's herp marketplace, it seems nearly every specimen
sold is carrying hidden traits of some sort. Rare indeed is the breeder that
has full knowledge of every trait present in every specimen in their
colonies! Yours have now been proven to be no exception! The thing to do now
is realize that two situations exist: If neither parent exhibits the trait
in question, then both parents are heterozygous for it. If only one parent
exhibits the trait in question, the other has now been proven to be
heterozygous for it. Go back to step one, using the new information you have
just learned, and recalculate the whole thing. Your results will now be
correct.
Q: My question isn't answered here, what do I do?
A: Well, write me about it silly. I'll even include it here for
others who may have the same question!
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