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Re: HYB: Punnett Square Question


Hello folks,

I did appreciate and enjoy Sharon's post, as always.  I'm keeping my
query on the list for the time being, so this will be long.  Don't try and
pretend you're surprised.  I think I may be losing my fear of displaying
my profound ignorance.  Probably part of the aging process.

Well, I've been working on the homework.  Maybe I can get help with
the areas I can't seem to get to crystallize for me.

>In the spirit of the hybridizing classes we held years ago when the list
>was smaller and a greater proportion of our members were interested in
>hybridizing, I'd like to suggest some "homework":
>
>1.      For each of the five types of tetraploids most often used to
>produce arilbreds [AAAA, AAAB, AABB, ABBB, and BBBB], go through the
>exercise of determining the type of gamete that will correspond with each
>row or column of a Punnett Square.
>2.      For each type, construct a square that represents a cross between
>two individuals of the same type.
>
All done, plus one more.
>
>The AAAB chart, like the ABBB chart I talked you through earlier should
>help you understand why we call the unbalanced types "relatively infertile"
>instead of dismissing them as sterile.
>
My biggest sticking point.  How do I read this in the square?  Or a chart
for that matter?  I know some of the theory here, but this I can't get to
gel
for me.

>The AABB chart should be enlightening, to say the least.  [Hint:  identify
>the underlying assumption of the Punnett Square that does not accurately
>represent amphidiploid genetics.
>
Well, I would say here it demonstrates the flaw in the quantum approach.
A 36 seed pod yielding a perfect statistical result would half, or 18, AABB
types, the other half would consist of 1 AAAA, 1 BBBB, 8 AAAB and 8
ABBB types (if I did the square correctly).  If the idea was crossing AABB
X AABB would result in offspring designated AABB in the system, then it
would be incorrect 1/2 the time.

As I understand the amphidiploid aspect, the Punnett Square would have
to be modified to accomodate the pairing.  The formula 3+2+1 = 3D6
does not work with the amphidiploid.  If AABB is a tetraploid
representation,
then you would have to think of A-A B-B as the amphidiploid counterpart,
where A-A transmit together rather than separately.  I didn't try to see if
if I could extend the square to accommodate a tetra x amphdiploid.

>Then......   After you have acquired a better feel for the fertile families
>and the relatively infertile groups, you'll be ready to tackle that
>complete set of charts I mentioned earlier.

Oh, I charted.  You wouldn't believe the amount of paper!  To do a chart
such as the ones Mike has posted on the HIPS website, I ended up having
charts separately just keeping the ancestors straight.  Unfortunately,
while it certainly was useful to a degree, I pretty much foundered in the
same areas as above.  Also, the charted one declined to bloom, so I
was looking around at others with some similar heritages to see if I
could apply all that tedious, time consuming work.  No takes. So this
feel for the fertility thing is still my sticking point, though I have vague
ideas of the area.  Fortunately, I am able to take advantage of information
others have worked out, both from this list and other sources.  Not
quite the same as really understanding, but useful until I can get hold
of the concept.
>
>MARY McCLELLAN must be judged against her peers, not later generations.

Welllll, she stood up pretty well this year against some decades later
generations in looks as well as growth habits.  And thanks for the great
description from Craig's 1964-65 catalog and the names of the contenders
for the first C.G. White medal.  The one I called SCARLET BUTTERFLY
should have been STRIPED BUTTERFLY in my previous post.  It was a
nice thing so now I'm wondering how these in the list stacked up in the
voting.

>this message is already too long and too technical for most tastes.
>
More than likely! :).  At one time I would have let this comment go
quietly because I think it's true for the most part.  But when I joined the
list several years ago (not from the beginning) and there was technical
information being bandied about, I read every post (still do).  I knew
then then I would never need the information because I had no plans
to do any pollinating...and if I did I couldn't imagine wanting to delve
any deeper than spreading pollen here and there to see what happens.
I swore when I started spreading that pollen, that I would limit it to
only that.  Well, ultimately I found myself beginning to a bit more
albeit in a haphazard, stop and start way.  So I have been the archives
and looked in WOI and visited your web page.  It is nice to know the
information is in the archives.  Useful that.  Also has the possibility of
having a query answered by real people with genuine interest.  I
appreciate the input there, even though the archives are frequently
not friendly to my computer.  So I posted to the list for that reason.
There is potentially another new talker who may come back later
and find they can use the information and remember it is there.  When
they are ready.  Maybe they will be faster learners.

Donald Eaves
donald@eastland.net
Texas Zone 7, USA


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