Hemlady said:Maurice, are you saying that a proliferation can produce a plant that is not necessarily exactly like the parent plant???
Actually, even a normal division can produce a plant that is not exactly like the parent plant. When these are obviously, visibly different, they are called "sports". In some of the plant species used in gardens many of the cultivars are related because they were produced by sports.
Unfortunately, producing a plant in any way, naturally or not, involves the possibility of errors. Not just the chance of an error occurring but the almost inescapable result of the errors that will occur with time. Some of the errors are mutations - genetic changes.
A new individual plant starts when the two cells (one from the pod parent and the other from the pollen parent) unite to produce one cell with the normal number of chromosomes and total genetic material. That single cell has to grow and divide into two new cells and they have to grow and divide and so on until there are millions and millions of cells that make the adult plant. Each time a cell divides there is a chance that there will be an error in duplicating the genetic material. Even though that chance is very small, because there are millions of cells in an adult plant there will be many cells with errors. The more a plant is vegetatively propagated the more errors will be accumulated. Those errors will nearly never be obviously visible to the naked eye since in a diploid an error would have to occur in the same gene in which a previous error had occurred for it to become visible (and it would need to be in a character that was obvious to the naked eye). In a tetraploid it would require errors in all four copies of a gene for it to become visible typically. However, their effects may be measureable using experimental techniques and by examining characteristics such as fertility, growth rates, etc.
The simplest example of this is with the Easter lily in the US. Only a few major producers grow most of the crop. They are reproduced by bulbs (vegetatively). There is only one apparent clone "Nellie White". Bulbs from the different growers should be more or less genetically identical - they are not. There are also noticeable differences in the plants from bulbs from different growers. This clone has existed for about the last 60 years so has accumulated genetic differences during that time as expected.
The scientific term for the genetic effects of continued asexual or vegetative propagation/division is Muller's ratchet.
