Founder effect. - Page 1

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by srilankagsd on 09 July 2008 - 14:07

Today i found a new term called founder effect thanks to Bravo.

After researching the web for the term founder effect I am confused. I am a fan of line breeding and some what inbreeding. It has its advantage and draw backs. I guess founder effect has something similar to line breeding. We normally line breed to replica features that we like from the dogs that we like from the past.

Please throw some lite to this field as i would like to know what others feel is right.

 


pod

by pod on 09 July 2008 - 15:07

Founder effect is a term that's usually applied to isolated populations like a breed or species, though it could be used to describe certain traits within lines.  And it's most often used to explain the perpetuation of a trait that has not been deliberately selected for, either by natural selection or in domestication.

For example.... I can't think of any dog related ones off the top of my head, so I've got a 'natural' one   Over here in West Wales we have a small coastal island, Skomer, that has a significant rabbit population.  They were introduced by settlers centuries ago and they brought with them a mixture of colours including blacks and particolours.  These colours do occur in normal circumstances in wild rabbit populations but here on Skomer the incidence is much higher than on the mainland. The rabbits live as a wild population so are subject to natural selection, but still the higher than normal percentage of unusual colours persist.

The high incidence of the genes responsible for these colours is a results of the founder population also having a high proportion, and the resultant colour anomaly is known as 'founder effect.'


by bravo on 09 July 2008 - 15:07

 Hi,

 

I am not sure what you mean by founder effect.  Are you using a translation site to translate English to Tagalog?  I believe that is the language of Sri Lanka but do not remember for sure.  Any way, translation sites cannot always give the correct meaning.  

 

I will try to explain what I think you might be interested in as you talk about breeding.  Labradoodles are a mix of the parent breeds of Standard Poodle, Labrador Retriever, and generally a soft coat Wheaten Terrier or another similar breed.  These breeders originated in Hawaii and very quickly to Australia where through the efforts of a few very dedicated breeders and many not so informed breeders they are trying to create a new breed of dog.   The original goal was to create a breed that was hypoallergenic and nonshedding with the temperament of therapy dogs.  They are just a couple of generations away from being recognized by their breed recognition authority, the UKC and AKC.  It is considered outcrossing and not line breeding nor inbreeding as you are combining bloodlines of different established breeds.  Every year there are a couple of new breeds introduced to the AKC.  This is how a new breed is created, but it takes many generations and stringent record keeping of pedigrees.   

 

The problem is that many people have just started crossing their Labrador Retrievers with a Standard Poodle and trying to sell them as F1 Labradoodles, meaning first generation Labradoodles.  The result is somewhat far from what the creators are trying to accomplish.  What ever one thinks of "designer breeds," I recommend studying the websites of breeders such as Cloud Catcher Labradoodles and Rutland Manor Labradoodles for information on their breeding practices.  They are both located in Australia.  You can also look at the website of the Australian Labradoodle Association for more information on their breeding practices.

 

This is not an endorsement of any breeding practice, just thought you might be interested in learning more about breeding and how new breeds are created.  As our beloved German Shepherd Dogs are so inbred at this time I feel it worth the effort to educate oneself on how some dedicated individuals are trying to bring in new bloodlines for the health of the breed.  

 

I will not breed two dogs who I know have produced offspring with HD or ED, and yes I know the resultant littermates scores are more indicative of an accurate ZW score.  However, I feel that ZW scores are almost useless and no one ever actually submits an early failing hip or elbow x-ray for publication and inclusion in the parents scorings.  This makes it very difficult to actually get a true ZW score.  Until we can isolate for the gene that causes hip dysplasia and elbow dysplasia so we know which dogs are carriers and should not be bred to each other, and until we have breeders who will abide by this, we will continue to breed dogs who suffer these inherited diseases.  The only way to produce a dog with HD or ED is to have bred two dogs who carry the gene.  Yes, not every puppy produced will become dysplastic, but they will themselves be carriers.  So when a breeder has a litter where one or more of the pups fail their hip and elbow tests, I believe they should not breed those two dogs with each other again.  You know that by producing offspring with the disease that you have bred two carriers of the disease.  I believe that all breeders should educate themselves on the genetics prior to breeding dogs.  I am not an expert, just trying to do the best I can with the information available.  There is an excellent book "The Genetics of the Dog," by A. Ruvinsky and J. Sampson available, which I highly recommend to any breede


VKH

by VKH on 09 July 2008 - 18:07

As people breed dogs, they are emphasizing certain traits or eliminating others, depending on their needs.
People can promote certain characteristics (coat color, size, ect.) by either
a) breeding pairs of dogs that share the desired qualities or by
b) allowing dogs to breed randomly but culling (removing from the gene pool) puppies from the litter that do not possess those characteristics.
In either case, the genetic frequency for the desired quality goes up in each generation.
The Founder effect is the result of Linebreeding, Inbreeding and/or outcrossing! determined by the breeder’s priorities. 

The Founder effect can be a natural process based on natural selection,
a population of dogs, on an isolated island or in a very remote part of the country is ravished by rabies, disease or some other natural catastrophe, ...
In this case, much of the genetic diversity is lost as the breeding population is reduced to a small number of individuals …


panzertoo

by panzertoo on 09 July 2008 - 21:07


pod

by pod on 09 July 2008 - 21:07

Ah, I've though of a dog related example.  The high incidence of the neurological disorder Hypomyelinogenosis in the UK of population of Bernese mountain Dogs is down to Founder Effect.

The breed was introduced in the late 60s with imports from Switzerland and Scandinavia.  New imports following on from the first half dozen or so were very few and far between, so the original dogs has a strong influence on the gene pool for many decades. 

In the 80s this new disorder was discovered and found to be inherited as a simple recessive, and so traced back to one of the early import where the mutation is though to have originated.  The inevitable inbreeding that took places to establish the breed in the UK is no doubt responsible for distributing the defect gene widely in the population.... hence the association between low diversity and Founder Effect.






 


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