Trying to understand genetics and I have a few questions

[tazcat70]

Can a chicken that is p+/p+ R/r+ have what is considered a "bad rosecomb"? Does anyone have a picture of this?

Linkage- Can someone please explain this to me. http://www.edelras.nl/chickengenetics/theory.html This is the website that I am looking at.

How does a 10% linkage change the gametic ratios from 9:3:3:1 to 14:4:1:1

I am sure that there is an algebra equation that will explain it, but for the life of me, I am not getting it.

I think that is it for now.

Thanks!

 

[Katy]

Sorry you know I'm no help on this!!

 

[Sonoran Silkies]

Linkage is when two genes are so closely located to each other than it is rare to inherit one gene from one chromosome and the other from the other chromsome. Now if the bird (or whatever creature) is homozygous, it really does not make a difference; there is only one option for each gene regardless of which chromosome it comes from. But if heterozygous, there is a difference in outcomes. The math--someone else will have to help you on that.

 

[tazcat70]

It is ok Katy. I appreciate the thought tho.

Sonoran- Ok, if the bird is Homzygous then the linkage doesn't even matter because it only has the same genes to pass down. Using the example on the web address (lav/lav mo/mo) since they are the same it doesn't matter if they are linked. However if you are trying to create the bird that is lav/lav mo/mo from 2 birds that are Lav+/lav Mo+/mo then you have to worry about linkage.

BTW: I do understand that these are just examples and the lavender and mottled genes are NOT linked together.

Ok, I think I have that part, just need the math...ugh. I hate algebra!

 

[Sonoran Silkies]

Me too

 

[Henk69]

This is a very interesting topic of genetics.
Ignoring it is no problem for most projects though.

Calculating these percentages is not that easy. Complexity builds up quickly.

I build a tool that can help to calculate the percentages.

Here is the example of fictional 10% linkage between lavender and mottled:
http://kippenjungle.nl/kruisingFlex...Lav+/lav,Mo:mo/Mo+&fgt=Lav:Lav+/lav,Mo:mo/Mo+

Copy and Paste if link does not work:
kippenjungle.nl/kruisingFlexCO.html?DATA=S;Fictional%20Lavender%20Mottle%20Linkage;;;kipkiezer_bestanden/;JPG;0,G;Lav;Lavender;;L,G;Mo;Mottled;;L,A;Lav;Lav+;;black;D;;W;,A;Lav;lav;;lavender;R;;;,A;Mo;Mo+;;;D;;W;,A;Mo;mo;;mottled;R;;;,C;CO;Lav;Mo;10;&mgt=Lav:Lav+/lav,Mo:mo/Mo+&fgt=Lav:Lav+/lav,Mo:mo/Mo+

With this you can change the settings (eg % crossing over) yourself:
http://kippenjungle.nl/WizardFlex2....;;D;;W;,A;Mo;mo;;mottled;R;;;,C;CO;Lav;Mo;10;

 

[tazcat70]

Thank you Henk! Now I don't have to do the math.

Can anyone help with this?

Can a chicken that is p+/p+ R/r+ have what is considered a "bad rosecomb"? Does anyone have a picture of this?​

 

[Henk69]

Quote:

Often you get a "high" rosecomb with square sides.
There are a few cockerels with such comb on this page: http://kippenjungle.nl/bruinzilverpatrijs.htm

 

[Chris09]

Refresh my memory is p+/p+ R/r+
a rose comb/ single comb cross?

Chris

 

[tazcat70]

Yes. They would be heterozygous for rosecomb.