inbreeding
- Thread starter Killer Chams
- Start date
sandrachameleon
Chameleon Enthusiast
adding to the tangent discussion - anyone else heard of the Doma (aka Vadoma) people who live near the Zambezi river valley?
DanSB
Avid Member
The Vadoma people make for an interesting case study in how evolution works. Their primary trait being ectrodactyly as we have some lovely pictures above illustrating (Thanks Kibu!). This is a trait that appears in the human genome world wide, although very rare especially as it confers no reproductive advantage in the majority of the world.
In this particular group due to the small population and rules against mating outside the tribe it is becoming more and more prevalent. Globally this deformity occurs on hands and feet and is linked to deafness. In the Vadomo population it occurs mainly on the feet and is not linked to deafness.
It is also reported that this particular genetic variation gives an advantage when climbing trees.
So what we have here is a trait that is dominant which means it will manifest physically if only one allele is present and is not life threatening and in this instance offers certain advantages.
Should the human race find itself with a survival advantage in being able to climb trees over being able to run fast we could have ALL been born with this trait.
Sometimes (rare as it might be) genetic variation in small populations can bring out traits in the genome that would have ordinarily been cancelled or absorbed in a larger population where no survival advantage was conferred.
Inbreeding can only be detrimental if there are detrimental traits already in the genome being passed along. The Vadomo are an excellent example of how this happens.
I am still confused about the Chameleon Genome causing total failures with inbreeding and certainly hope someone with some insight on how DNA combines in Chameleon reproduction to cause total failure...
Dr O
Veterinarian
i've come late to this thread, but the thought above was one of my first thoughts as well. i do not know chameleon lineage back to when Madagascar split from the mainland, but as many animals from Madagascar are so unique, i wonder if there may be completely different answers for different locales; panthers vs. veileds, for instance. i found Jim Flaherty's report fascinating that at least a dozen clutches were abominations under his roof---Jim, can you clarify which species they were?
as a very Darwinian-minded person and believer in natural selection (although i have read many scientific articles recently that have made me even question those beliefs), if it ain't meant to be, nature will phase it out. i think Chris Jury had an excellent point regarding diseases. i certainly can see that perhaps the F1 generation onwards may look and act normally for a period of time, however it seems that eventually a virus or bacteria will also evolve and take advantage of an innate weakness with potential massive losses of the population. it happens in livestock veterinary medicine all the time. and even then, the strong survive. Ebola and the other hemmorhagic fever diseases of the Congo have approximately a 90% mortality rate, but 10% will make it. and they will pass on those stronger, disease-resistant genes and so on.
i guess part of my point is that nature is just full of checks and balances. and in the scheme of things, we're talking about a few years or perhaps decades of what inbreeding may do; imo the real answer won't even reveal itself for potentially hundreds/thousands/millions of years.
in terms of the K. matschiei, i would have no problems trying to breed them if there were no other course, but i would also track the lineage very carefully and of course let any interested buyer know exactly what they are dealing with.
Dr O
Veterinarian
and even the House Targaryen from Game of Thrones mate incestously for three centuries before they allow the mingling of outside blood. but of course, perhaps that also explains their purple eyes and silver hair........(in the books at least; apparently the contact lenses were too painful for the actors).
so sorry to post this, i just couldn't help myself.
so sorry to post this, i just couldn't help myself.
Carlton
Chameleon Enthusiast
Just a little reminder about wild individuals who may happen to breed with their direct relatives: they have this major culling agent called the Cold Cruel World that will take care of the less fit young such a pairing would produce. Captive chams who are less fit in subtle or undetectable ways can survive to pass these defects on because we take care of them. And, these defects can be magnified as more and more of the offspring carry the defect. What started out as a very recessive or rare trait eventually can be common (hip displaysia in dogs for example). In the wild, the fittest individuals survive to pass on their genetic makeup, inbred or otherwise. At some point for every species (and it is different for every species), the effects of inbreeding will create a fitness bottleneck that can doom the entire population. This is one of the threats to endangered species. Even if we remove all the habitat, poaching, disease, or other environmental threats to the species they can still be lost to inbreeding depression.
Carlton
Chameleon Enthusiast
Well, the degree of genetic drift between cham species does vary. It could be that the species that dispersed soonest and farthest away from the mythic "cradle of chameleon origin" are now the most genetically distinct which is why they are unable to hybridize. They no longer got "refreshers" from the original parent populations once they were cut off by distance. This would include far flung species like common chameleon, veiled chameleon, possibly the Comoros, Namaqua, and eventually between the African mainland species. But we don't really know for certain where that original cradle was, where or when the divergences occurred.
I also suspect that plain old adaptation to new habitats plays a role in genetic drift. If the colonizing animals had to adapt a lot (and fast) to survive wherever they dispersed, it would speed up their rate of development into a new distinct species. I remember reading about the rapid speciation rate amongst rainforest birds. Many of these birds don't even cross clearings in the rainforest to breed. They become genetically isolated pretty fast because they don't move much. One major reason why deforestation causes so much loss of diversity. All those little isolated subspecies and races disappear the more the forest is fragmented.
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DanSB
Avid Member
I am at least 10 years out of date, anything online to illustrate any new counters?
I think that is true when we are talking on the grand scale concerning the entire population of the species; however, for the purposes of breeding small groups of chameleons that can potentially receive vigor from additional lines it isn't likely to be so far out that a problem can be detected.
I still think that in theory if you have an individual lineage with very few bad traits and can carefully breed them out you can wind up with a healthy population from a very small group.
DanSB
Avid Member
Great line!
I got really interested in space time theory only because I love the idea of the possibility to actually be able to look back in time and figure out mysteries like this... I think we can get so far by mapping Genetic information then we just hit another road block. And as far as I know the fossil record for chameleons is nearly non-existent.
Dr O
Veterinarian
Dr O
Veterinarian
Nothing that I can point to offhand. Just about a decades worth (wink) of reading various articles in Smithsonian, Discover, National Geographic and the like.
Has anyone ever read "The Blind Watchmaker"? It's a fascinating deconstruction of Darwinian theory.
