RSS

Cat amongst the pigeons?

26 Sep

Because of the way it’s written it may take a couple of attempts to absorb but something very relevant to Glen of Imaal Terriers.

”GENE POOL” In our breed with global small numbers but wide range of physical variation– unlike more uniform & established bigger breeds-we have to be careful talking about ”gene pool” as it is not advisable to simply randomly cross individuals which don’t show common ancestors in a 3 or 5 generation pedigree to ”increase the gene pool’. Already for some characteristics there is too much variation- & arguably for these characteristics the gene pool is ”too big” —on the other hand for health reasons it is dangerous to narrow down the range of variation in other sometimes invisible characteristics involving DNA & its phenotypic expression via RNA for the many biochemical processes essential for life & efficiently working joints etc —-especially with dominant genes it is easier to increase problem gene frequencies inadvertently than to reduce them again even the effects of genetic drift kick in-especially when international travel was so difficult –So the breeder in a low numbers breed with a wide range of physical variation is walking a tightrope between fixing the desired shape & maintaining health & soundness…ie to increase the frequency of & bring in desired genes for the shape, angulation etc required by the standard by selectively breeding for type & bringing in type from outside- -whilst simultaneously maintaining health & soundness by weeding unsound or unhealthy animals out of breeding but not breeding too closely related individuals together except when there is not a suitable less closely related source of the characteristics the breeder is seeking to fix in by doubling up on– thus increasing the amount of useful genetic variation governing biochemical body processes etc — some characteristics are determined by several different sets of polygenic genes & others by surprisingly few genes– hopefully more info will be forthcoming from the dog genome project as scientists look at its many different implications

Delia Shepherd.

 

Advertisements
 
2 Comments

Posted by on September 26, 2013 in General dog things, General Glen Things

 

Tags: ,

2 responses to “Cat amongst the pigeons?

  1. Woodie

    September 26, 2013 at 9:26 am

    Polygenic Inheritance

    A polygenic trait is one where it is thought that many genes control a single trait, and it is the ‘quantitative sum’ of the ‘values’ of those genes that define the degree to which the trait is expressed.
    Such polygenic traits typically show a continuous range of expressions (=variations).
    This mode of inheritance applies to many of the most important characteristics breeders need to focus on in a breeding program. See also “effective population size’

    http://www.tenset.co.uk/ba/gen_poly.html

     
  2. Marty

    September 26, 2013 at 2:49 pm

    Provocative. Well worth the time to read if you’re a breeder or intending to be. Marty Dagneau-Bates Glenbride Irish Dogs

     
 
%d bloggers like this: