Problemi inbreeding R. leachianus
Inviato: gio gen 08, 2009 1:10 am
Ciao a tutti, vorrei affrontare un argomento riguardante i possibili casi di problemi dovuti all'inbreeding tra R. leachianus per preservare una determinata locality. Come tutti ben sappiamo gli esemplari importati dai vari henkel, repashy, fast ecc non furono più di due coppie per locality (e le importazioni dalla nuova caledonia sono bloccate quindi il sangue che gira è sempre quello). Quindi a me, da convinto purista, vien da pensare se non sia pericoloso voler a tutti i costi mantenerla a discapito della loro futura salute? Mi piacerebbe sapere cosa ne pensano manu e altri esperti a riguardo.
Di seguito riporto il link di una interessante discussione sul forum di repashy a cui ha partecipato de vosjoli
http://www.forums.repashy.com/rhacodact ... ame-2.html
e qui sotto secondo me uno degli interventi piu interessanti di repashi
Philippe's idea is really the best one for the long term success of keeping the morphotypes alive in captivity. If we look at the offspring from even pure localities, there is a variation that can overlap with the offspring of another local. if you know statistics, there is a "standard deviation" factor. Most of the offspring from a local will have similar traits, but there will be a percentage that are outside of the curve. If these individuals are bred into the captive locality population, they will change the "look" of even the pure locality specimens.
As Philippe said... even with dogs for example, it is breed standards that keep German Shepherds looking the same, not just that fact that only German Shepherds are used to breed them. In ten generations, you could take pure pedigreed German Shepherd offspring, and produce something that doesn't look like a classic German Shepherd anymore if you weren't paying attention to the breed standards.
So what I am saying, is that even by breeding locality specific animals, if we don't have a "locality standard", in a matter of generations, our locality specific and pure animals will not accurately represent what is found in nature.
If we look and Pine Island and Moro for example, we can see certain traits that are more prevalent in one population over another, but there are definitely animals produced from each locality that share traits, and could not be discerned as to where they were from.... So if we take the traits that ARE different about these localities, and use this as a "locality standard" we can produce two types of gecko that are different looking, and best represent the differences that do exist. If a Moro gecko offspring shows classic Pine Island traits, then cross breeding this animal to the Pine island stock will increase genetic diversity as well as help produce two different looking lines...... Does this make sense to anyone?
I know people hate the dog comparison, but it really is applicable here. Dogs are genetically the same species, but breeds look different because we made them that way. Leachianus look different because of geographic isolation, but have not been isolated long enough to be genetically different.
If we use "locality standards", then breeding type A and type B, or Type A and "henkeli" together would not be something that one would want to do to fix "locality types" .... So it does not promote crossing of all leachianus. Just the ones that have "trait overlap" such as the various island morphs.
Many of these islands are close to each other and pine island, and it is not difficult to assume that there is occasional movement of geckos via rafting during storms that can change the "look" of a population from decade to decade. The populations on some islands are small enough, that a single introduced male, could change the look of the whole population in a matter of generations......
If we look at selective breeding as creating our own new "locality standard" Then someone could create their own "Island" by selecting traits from the available gene pool and creating their own goals. I can look at my snowflake line as "Island Allen" and take all the high pink and white offspring from various other "locality types" to produce my own "Island Allen Locality Type Standards"
So if we look at creating your own selectively produced line as creating your own Island, it makes sense. "locality standards" will allow us to keep island localities "pure" by description, while allowing greater genetic diversity.
The work of Aaron Bauer has shown that the genetic difference is very small. Captive breeding has shown thet there is a great morphological variation within even the locality specific populations. So even if we breed locality "pure" lines only, we are not going to end up with the same animals we see in nature unless we set "locality standards"
So what is more important.. Keeping genetics pure from a limited genepool of a population, even though the animals will stop looking like what they do in nature because of inbreeding and human selection within that line..... Or breeding for the "locality standard" differences we see in nature, using a wider genepool..... ?
We must remember, that Aaron has proved there is no significant genetic difference.. So that means the only difference is morphological (visual and structural). So if we are not breeding fro these visual differences, and setting a standard for them.....and instead breeding for genetic differences which aren't even there, WTF are we thinking?
I am not talking about widespread panic and crossing of lines, I am talking about the introction of outside localities that meet "type standards"
And of course none of this means anything if these standards are not developed and accepted by the main breeders.
Food for thought, Allen
Di seguito riporto il link di una interessante discussione sul forum di repashy a cui ha partecipato de vosjoli
http://www.forums.repashy.com/rhacodact ... ame-2.html
e qui sotto secondo me uno degli interventi piu interessanti di repashi
Philippe's idea is really the best one for the long term success of keeping the morphotypes alive in captivity. If we look at the offspring from even pure localities, there is a variation that can overlap with the offspring of another local. if you know statistics, there is a "standard deviation" factor. Most of the offspring from a local will have similar traits, but there will be a percentage that are outside of the curve. If these individuals are bred into the captive locality population, they will change the "look" of even the pure locality specimens.
As Philippe said... even with dogs for example, it is breed standards that keep German Shepherds looking the same, not just that fact that only German Shepherds are used to breed them. In ten generations, you could take pure pedigreed German Shepherd offspring, and produce something that doesn't look like a classic German Shepherd anymore if you weren't paying attention to the breed standards.
So what I am saying, is that even by breeding locality specific animals, if we don't have a "locality standard", in a matter of generations, our locality specific and pure animals will not accurately represent what is found in nature.
If we look and Pine Island and Moro for example, we can see certain traits that are more prevalent in one population over another, but there are definitely animals produced from each locality that share traits, and could not be discerned as to where they were from.... So if we take the traits that ARE different about these localities, and use this as a "locality standard" we can produce two types of gecko that are different looking, and best represent the differences that do exist. If a Moro gecko offspring shows classic Pine Island traits, then cross breeding this animal to the Pine island stock will increase genetic diversity as well as help produce two different looking lines...... Does this make sense to anyone?
I know people hate the dog comparison, but it really is applicable here. Dogs are genetically the same species, but breeds look different because we made them that way. Leachianus look different because of geographic isolation, but have not been isolated long enough to be genetically different.
If we use "locality standards", then breeding type A and type B, or Type A and "henkeli" together would not be something that one would want to do to fix "locality types" .... So it does not promote crossing of all leachianus. Just the ones that have "trait overlap" such as the various island morphs.
Many of these islands are close to each other and pine island, and it is not difficult to assume that there is occasional movement of geckos via rafting during storms that can change the "look" of a population from decade to decade. The populations on some islands are small enough, that a single introduced male, could change the look of the whole population in a matter of generations......
If we look at selective breeding as creating our own new "locality standard" Then someone could create their own "Island" by selecting traits from the available gene pool and creating their own goals. I can look at my snowflake line as "Island Allen" and take all the high pink and white offspring from various other "locality types" to produce my own "Island Allen Locality Type Standards"
So if we look at creating your own selectively produced line as creating your own Island, it makes sense. "locality standards" will allow us to keep island localities "pure" by description, while allowing greater genetic diversity.
The work of Aaron Bauer has shown that the genetic difference is very small. Captive breeding has shown thet there is a great morphological variation within even the locality specific populations. So even if we breed locality "pure" lines only, we are not going to end up with the same animals we see in nature unless we set "locality standards"
So what is more important.. Keeping genetics pure from a limited genepool of a population, even though the animals will stop looking like what they do in nature because of inbreeding and human selection within that line..... Or breeding for the "locality standard" differences we see in nature, using a wider genepool..... ?
We must remember, that Aaron has proved there is no significant genetic difference.. So that means the only difference is morphological (visual and structural). So if we are not breeding fro these visual differences, and setting a standard for them.....and instead breeding for genetic differences which aren't even there, WTF are we thinking?
I am not talking about widespread panic and crossing of lines, I am talking about the introction of outside localities that meet "type standards"
And of course none of this means anything if these standards are not developed and accepted by the main breeders.
Food for thought, Allen