"As far as I know, incomplete dominance and codominance are the same
thing"
Couldnt have said it better myself !
Visually, in-complete and co-dom are both unidentifiable from one to the
other. The only way to know if something is in-complete or co-dom, is to do
DNA typing. For the most part...the term "Co-Dominant" is the easiest and
broadest way to describe partial dominance, incomplete dominance,
codominance, lack or absence of dominance, intermediate dominance, imperfect dominance, egalitarian dominance, and transdominance.
Anyone who believes animals they're working with may be anyone of those
above traits can call their project as one being of "Co-Dominant" genes.
There was recently a discussion on my own Forums on the ability for one to
know whether or not a specific animal was "in-complete" or "Co-dom", well
unless you've got access to a DNA typing lab, its nearly impossible to
discern the 2.
But what we can do is make an educated guess by the results after breeding
the animals believed to be either co-dom or incomplete. here are some
punnett squares for example....
Example for Incomplete Dominance:
This relationship has the same effects as above for homozygous individuals.
For heterozygous individuals, the dominant and recessive traits blend into a
middle ground.
R w
R RR Rw
w wR ww
R is red, w is white. Rw is pink, since red is incompletely dominant over
white.
When breeding in-complete carriers together you get offspring that will
reflect either one of the parents or a combination of both. If you look
above at the punnett square, both parents are "RW" which is PINK, when bred
together you get offspring that will be "RR" which is Red, "WW" which is
white, and "RW" / "WR" which is pink.
Example for Co-Dominance:
In co-dominance, neither phenotype is dominant. Instead, the individual
expresses both phenotypes.
A I
B BA B
I A O
In the square above "AI" and "BI" would be the carriers with "I" being the
co-dominant gene. The resulting offspring would be "AB" which would be more
"Co-Dom" carriers, "A" and "B" would be "normals" and the combination of
both "I" genes would create a "super" form of that particular trait, in this
case for clarity, "O" is being used.
For comparisons sake and for a visual of real life outcomes...
Lets say that a "Purple" cornsnake was a carrier for incomplete dominance,
when you breed 2 "purple" cornsnakes together...you would end up with babies that were "Red", "Blue" and "Purple" and vice versa if you bred "Red" to
"Blue", you would also get offspring that were "Red", "Blue" or "Purple".
If the "Purple" cornsnake was Co-dom, you would end up with babies that were "Normal", "Purple", and then last but not least "Super Purple" which would be the 2 co-dom genes combining. When breeding this "Super Purple" to ANYTHING...all of the resulting offsping would receive one of the 2 co-dom
genes. and thus making them all "Co-Dom". But in some variations/mutations ,
the "super" form looks visually like the original carriers thus making it
hard to determine whether or not it is in fact a carrier for both genes.
Some mutations which produce a "Super" form typically produces a much
crisper/enhanced version of the original carriers and makes it easy to
identify. But, in any case...to truly tell if that particular animal is
carrying both genes...all of their resulting offspring will look visually
like the carriers. If they're carrying just one of the genes, than you would
get a "percentage" and not all of the resulting offspring that would look
visually like the original carrier.
But I don't want a poodle or a collie...I want borders.....
