We know today that the larger part of the DNA of all eucaryotes is non-encoding and this part can change in size from species to species without effecting active genes. We will treat this phenomenon in more detail in the next section. The amounts of DNA correlate primarily with the degree of ploidy, while differences in the size of the genome are often secondary causes for evolutionary changes. The values of species with several ploidy races behave therefore often not as integer multiples of a basic amount. More often, the increase of the amount of DNA as a function of the degree of ploidy results from a logarithmic function, a saturation curve.
Some striking correlations connected to the evolution of plants are nevertheless obvious.
Changes in the amount of DNA in the course of adaptive radiation. 1. and 2. The amounts of DNA are usually higher in gymnosperms than in woody angiosperms. The highest values were detected in Pinus -species and cycads. This is true for both monocots and dicots.