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It would be a good idea to explain the term "heterozygocity".
I am currently looking to update Wagyu and am about to discuss breeding practices once those genetics left Japan. This article seems to focus more on botany. I also notice that F2 generation has been removed. Should a Genetic hybrid article be created that encompasses F1, F2, F3 ...? Jaydjenkins 04:53, 7 December 2006 (UTC)
I deleted the sentence suggesting F2 generations were a cross between F1 generations, that's incorrect, F2s are the result of selfing of the F1. Although you could cross two F1 hybrids the genetics would be so crazy it would be pointless. In genetics the F2 generation is very important, usually a line with a desirable phenotype is backcrossed to the parental line to produce a hetereozygous F1 generation, selfing then recovers the mutant in the F2 generation in a Mendelian ratio. —Preceding unsigned comment added by 71.8.193.164 ( talk) 11:01, 7 April 2010 (UTC) DAMN BRO THIS HELPS
The second half of the second paragraph of this article currently reads as follows:
"Because of the almost pure homozygosity of the parent lines, F1 hybrids have a very high level of heterozygosity. As a result of this, F1 hybrids display improved growth and yield characteristics."
I'm no expert, but this does not sound quite accurate to me. I can think of a situation where crossing two purely homozygous parent lines will NOT give us a heterozygous F1 generation:
P Generation: aa x aa
F1 Generation = aa
In this situation, crossing two homozygous parent lines has given us a homozygous F1 generation. That parent lines are inbred and homozygous is irrelevant to the fact that the F1 hybrids are heterozygous.
Rather, the heterozygosity of the F1 generation observed in agronomy/hybrid seed production can be attributed to the relative dissimilarity between the two parent types (the less closely related they are, the less chance that multiple copies of the same “bad” alleles will be inherited).
The fact that parent lines are usually inbred and homozygous in seed production is simply to ensure that the F1 generation are phenotypically uniform; if both parent lines were heterozygous, the F1 generation would display a wide range of phenotypic variation, not something that farmers expect when handing over their folding-stuff to buy fancy hybrid seeds.
So in summary, heterozygosity (and therefore, improved growth and yield characteristics) of F1 generation is due to the marked differences between the two parent lines, whilst the pure homozygosity of the parent lines ensures a uniform F1 generation.
I think that the whole introduction could be made more concise and simple, but for now, I have made a small number of changes to correct this inaccurate paragraph. It now reads:
In agronomy, the term “F1 hybrid” is usually reserved for agricultural cultivars derived from two different parent cultivars, each of which are inbred for a number of generations to the extent that they are almost homozygous. The divergence between the parent lines promotes improved growth and yield characteristics through the phenomenon of heterosis, whilst the homozygosity of the parent lines ensures a phenotypically uniform F1 generation.
Sridge 12:51, 21 December 2006 (UTC)
There appears to be a contradiction in the current listing of disadvantages of F1 hybrids, specifically the following statements:
"F1 hybrids lack genetic diversity, due to the inbred parental lines. F1 hybrids are highly heterozygous and can hence harbour large levels of genetic diversity."
Which is correct?
Peppergrower 08:04, 15 October 2007 (UTC)
Atulsnischal 15:21, 15 October 2007 (UTC)
Atulsnischal 16:31, 16 October 2007 (UTC)
None of the sources that I've looked at use a subscript for F1 hybrid. What's up? Dicklyon ( talk) 18:34, 14 June 2009 (UTC)
What are you looking at? Try Britannica online http://www.britannica.com/EBchecked/topic/199610/F1-hybrid, or any genetics textbook. Nadiatalent ( talk)
So how about considering the other changes that you backed out so flippantly, rather than going into a tailspin over getting Wikipedia to match other sources that have sloppy typesetting? You've reverted to a statement about hysteresis, which makes no sense in this context ... I will not touch this page again!! Nadiatalent ( talk)
Here's the relevant diff that includes other small changes that someone might want to work on. Dicklyon ( talk) 00:19, 15 June 2009 (UTC)
This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||||||||||||||||
|
It would be a good idea to explain the term "heterozygocity".
I am currently looking to update Wagyu and am about to discuss breeding practices once those genetics left Japan. This article seems to focus more on botany. I also notice that F2 generation has been removed. Should a Genetic hybrid article be created that encompasses F1, F2, F3 ...? Jaydjenkins 04:53, 7 December 2006 (UTC)
I deleted the sentence suggesting F2 generations were a cross between F1 generations, that's incorrect, F2s are the result of selfing of the F1. Although you could cross two F1 hybrids the genetics would be so crazy it would be pointless. In genetics the F2 generation is very important, usually a line with a desirable phenotype is backcrossed to the parental line to produce a hetereozygous F1 generation, selfing then recovers the mutant in the F2 generation in a Mendelian ratio. —Preceding unsigned comment added by 71.8.193.164 ( talk) 11:01, 7 April 2010 (UTC) DAMN BRO THIS HELPS
The second half of the second paragraph of this article currently reads as follows:
"Because of the almost pure homozygosity of the parent lines, F1 hybrids have a very high level of heterozygosity. As a result of this, F1 hybrids display improved growth and yield characteristics."
I'm no expert, but this does not sound quite accurate to me. I can think of a situation where crossing two purely homozygous parent lines will NOT give us a heterozygous F1 generation:
P Generation: aa x aa
F1 Generation = aa
In this situation, crossing two homozygous parent lines has given us a homozygous F1 generation. That parent lines are inbred and homozygous is irrelevant to the fact that the F1 hybrids are heterozygous.
Rather, the heterozygosity of the F1 generation observed in agronomy/hybrid seed production can be attributed to the relative dissimilarity between the two parent types (the less closely related they are, the less chance that multiple copies of the same “bad” alleles will be inherited).
The fact that parent lines are usually inbred and homozygous in seed production is simply to ensure that the F1 generation are phenotypically uniform; if both parent lines were heterozygous, the F1 generation would display a wide range of phenotypic variation, not something that farmers expect when handing over their folding-stuff to buy fancy hybrid seeds.
So in summary, heterozygosity (and therefore, improved growth and yield characteristics) of F1 generation is due to the marked differences between the two parent lines, whilst the pure homozygosity of the parent lines ensures a uniform F1 generation.
I think that the whole introduction could be made more concise and simple, but for now, I have made a small number of changes to correct this inaccurate paragraph. It now reads:
In agronomy, the term “F1 hybrid” is usually reserved for agricultural cultivars derived from two different parent cultivars, each of which are inbred for a number of generations to the extent that they are almost homozygous. The divergence between the parent lines promotes improved growth and yield characteristics through the phenomenon of heterosis, whilst the homozygosity of the parent lines ensures a phenotypically uniform F1 generation.
Sridge 12:51, 21 December 2006 (UTC)
There appears to be a contradiction in the current listing of disadvantages of F1 hybrids, specifically the following statements:
"F1 hybrids lack genetic diversity, due to the inbred parental lines. F1 hybrids are highly heterozygous and can hence harbour large levels of genetic diversity."
Which is correct?
Peppergrower 08:04, 15 October 2007 (UTC)
Atulsnischal 15:21, 15 October 2007 (UTC)
Atulsnischal 16:31, 16 October 2007 (UTC)
None of the sources that I've looked at use a subscript for F1 hybrid. What's up? Dicklyon ( talk) 18:34, 14 June 2009 (UTC)
What are you looking at? Try Britannica online http://www.britannica.com/EBchecked/topic/199610/F1-hybrid, or any genetics textbook. Nadiatalent ( talk)
So how about considering the other changes that you backed out so flippantly, rather than going into a tailspin over getting Wikipedia to match other sources that have sloppy typesetting? You've reverted to a statement about hysteresis, which makes no sense in this context ... I will not touch this page again!! Nadiatalent ( talk)
Here's the relevant diff that includes other small changes that someone might want to work on. Dicklyon ( talk) 00:19, 15 June 2009 (UTC)