Modifications (genetics)
In opposition to mutations, modifications are included in the band width of the genome of an individual creature. Mutation takes place when the DNA structures is partnered by the wrong structure (Proper rule: A=T and G=C for DNA and for mutation: A=G or A=C or T=G or T=C and G=A or G=T or C=A or C=T). Modifications are dependent on the plentiful of the substrate, light, warmth, stress, training, and so on.
A modification is a change in the physical appearance of an organism (phenotype) caused by environmental factors. Modifications can either be uninheritable or inheritable. In both cases, there is no change to the primary DNA sequence (genotype), rather an influence on gene expression which is the cause of the altered phenotype.[1]
Occurrence
Modifications often occur in domesticated animals: Decrease of the brain weight by 20 to 30 percent, decline of the cerebral cleavage especially in the projection areas of the sense organs, changes in the hormone status and in the behavior.
Modificability
In heredity the genes of the parents are passed on to their offspring unchanged. That is why the organisms which carry the same genotype should be identical in every feature. However, this is not the case. Due to environmental conditions they can vary from each other up to a certain point. There are two types of modifications: the continuous modification and the switching modification.
To illustrate the modificability you can take a look at our cultivated plants. The harvest of those plants do not only depend on the quality of the seeds but also greatly on environmental factors like the condition of the soil, the nutrient content of the soil, the fertilization, the humidity and temperature as well as the interference of other plants.
Example: Dandelion
If you take a lowland dandelion and plant half of it in the lowland and the other half in the mountains the result will be a dandelion with big leaves in the lowland and one with small leaves in the mountains. The reason is that in the lowland the environmental conditions are different from those in the mountains.