So yes, the first generation of clones will be almost an exact match. I say almost because of genetic mutation, which is always possible. The more clones you take from clones, the more genetic mutations will exist.
The mother plant will also experience genetic drift over time. Some strains happen faster than others, but eventually the mother plants need replacement also.
Genetic drift does not occur with asexual reproduction such as with vegetative propogation in plant cloning. This is because there is no sexual reproduction and as a result, no recombination which is required for genetic drift to occur.
Its an interesting topic this one. The theory that clones degrade in some way through successions due to mutations is thin, but not at all impossible.
Clones are classified as asexual reproduction which can occur naturally through organisms that intentionally produce identicle organisms of themselves through mitosis. Or through practices such as vegetative propagation which is known as cloning for cannabis.
The thoery behind succesive cloning degradation, is through genetic mutations. Although it has been shown that several generations of mutations can have an effect on genetic variances. It is a very small effect. Some plant species can only reproduce through vegetative propogation and so have gone through many centuries of cloning. Some species have naturally cloned for millions of years (
Bdelloid rotifers).
I believe the differences people see are more related to phenotype plasticity, where through environmental conditioning, changes the phenotype expressions of a certain plant.
There is also the possibility that pathological diseases can cause problems that stay with the plant through successions. This may just as likely be the cause.
One thing seems clear to though, is that successive cloning does not automatically degrade the genetics and if the original or successive genetics are well looked after, is a high possibility it will perform as well as its original mother. There are many people who have cloned the same genetics for decades and some species of plants have been carried over for centuries. Many organisms, do this naturally without third party intervention. Which is a natural process of these organisms. So its hard to believe that this is a genetic aspect, but likely more related to phenotype expression or pathological diseases.
