Inbreeding in wild populations ?

[LaughingDove]

Another example of this is in Tristan da Cunha where there supposedly was a founding population of 7 females and 8 males and this caused high rates of asthma and glaucoma. This I suppose could also happen with species that are going from a very small founding population though I think there would be more natural selection in animals because with people they would survive things resulting from inbreeding whereas in a wild population any animals that end up with health problems would die leaving the overall population without those problems and this wouldn't happen in a human example.

 

[Hix]

An example of this in humans would be the spread of Haemophilia in Europes royal families in the 19th and early 20th centuary. That did not occurr because of inbreeding as critics of royals would attest but simply the natural spread of a genetic disease within a small population

But that IS inbreeding. As I said earlier, inbreeding increases the frequency of mutations. If the royals hadn't been breeding with related 'stock', then the frequency of the disease would have appeared much lower and it wouldn't have garnered the reputation it has today.

And beware that the disease is actually more prevalent than many people understand, and strictly speaking it is not a disease that affects only males. The disease is sexlinked, carried on the X chromosome. Males have the disease because their Y chromosome can't compensate for the mutated X, whereas heterozygous females have one good X chromosome along with the mutant one.

But homozygous females are never carried to term.



Hix

 

[Teddy Dalton]

In one of the reptile husbandry books that I have, in the chapter about breeding, it says that reptiles in particular are quite robust in terms of how many levels they can take, an experiment with breeding garter snakes siblings back to each other generation after generation (not even once off inbreeding, but the babies of inbred snakes being inbred themselves, and their own offspring inbred again) resulted in no visible defects until the 11th generation, when there was a small litter of 3 snakes that came out albino. i think it is quite possible that animals inbreed routinely in the wild such as lizards or snakes that after a hurricane are left stranded on a totally new island, new populations could be started from only a few individuals or from a single gravid female and her resultant offspring. as well as that parthenogenesis comes into play where a female lizard may end up on an island where she is the only one of her species, have all male babies by way of parthenogenesis (unlike humans where males are XY and females are XX, some reptile species are the other way around, males are WW and females are WZ, thereore when a female has partho babies, instead of taking half of the fathers and half of the mothers dna, it takes half of the mothers dna and replicates it, in a species where the females are XX, that means partho babies are all females, in species where females are designated by 2 differing chromosones such as WZ, it will make zygotes that are either WW or ZZ, since ZZ is garbage, these are not viable and the only babies born will be WW, and therefore male) and now since the island will only have that 1 female and her male offspring (in the absence of any additional individuals arriving by happenstance) the only option for colonization will be for those sons to breed with their mother once sexually mature. it is probable that some species (such as the komodo dragon, which inhabits small, isolated islands, has the WZ for males, WW for female arrangement, and has been documented to have the ability to produce offspring by parthogenesis) have come to where they are today through inbreeding like this, especially in very isolated island like those found in the pacific.

 

[jay]

But that IS inbreeding. As I said earlier, inbreeding increases the frequency of mutations. If the royals hadn't been breeding with related 'stock', then the frequency of the disease would have appeared much lower and it wouldn't have garnered the reputation it has today.



Hix

Incorrect Hix


The Royal occurance of Haemophilia was not caused by, increased by or made more intense by inbreeding. It followed the typical habit of this genetic mutation.
The Haemophilia occurred as a spontaeous mutation in Queen Victoria, as is typical of this genetic disease. her parents weren't closely related. She passed the disease on as is typical of the gene, one son had haemophilia, two daughters were known carriers. The famous example of her granddaughter, the Empress Alexandra of Russia was a carrier, she passed the disease on to her son, at least one of her daughters probably was a carrier. She did marry a second cousin but that did not contribute to the dieseas spread or intensity. She could have married an Australian Aboriginal, a person as distantly related to her as could possibly be and her son would still have had a 50 per cent chance of having haemophilia.
Haemophilia was at its greatest spread in Queen Victorias great children but by two generatons later it had died out due chance, carrier daughters had no children to pass it on, Hamophiliac sons died young or had no daughters to carry it on. This is typical of the disease.

 

[Hix]

Incorrect Hix

Jay,

While I hate being wrong, it appears I am in this case. Research on the internet has shown me that the royal families of Europe aren't quite as incestuous as I believed them to be, and while I would like to see a big family tree for the royals (which I couldn't find), I also found no evidence to refute any of your statements.

I stand corrected, and little more informed.



Hix