The diversity of the living world is staggering. The virtually infinite variations on life are the fruit of the evolutionary process. All living creatures are related by descent from common ancestors.
Biological evolution is a process of descent with modification.
The DNA of an organism plays the central role for its existence. Its sequential arrangement forms chromosomes . Due to the rapid development of sequencing technology evolution can be studied in the form of numerous DNA sequences , certain stretches of DNA that can be described by the letters A,C,T and G. Many similar DNA sequences from different species have common ancestors in evolution. The relationship among sequences are described by phylogenetic trees . Phylogenetic trees do not merely allow for an exact classification of life forms, but also give hints to yet unknown properties of organisms, as well as insight into the mechanisms of evolution.