(1) The study of phylogeny
Phylogenetics is the scientific study of phylogeny. Phylogeny pertains to the evolutionary history of a taxonomic group of organisms. Thus, phylogenetics is mainly concerned with the relationships of an organism to other organisms according to evolutionary similarities and differences. Phylogenetics, therefore, is a part of the biological systematics, which has a wider scope. The latter involves not only the phylogenetics of organisms but also the identification and classification of organisms. It is also related to taxonomy, which is a branch of science concerned also in finding, describing, classifying, and naming organisms, including the studying of the relationships between taxa and the principles underlying such a classification. Phylogenetics provides information to taxonomy when it comes to classification and identification of organisms.
In phylogenetics, DNA sequencing methods are used to analyze the observable heritable traits. It also makes use of a phylogenetic tree which is a diagram to show the hypothetical evolutionary histories and relationships of groups of organisms based on the phylogenies of different biological species. The phylogenetic tree has been used to understand biodiversity, genetics, evolutions, and ecology of organisms.
Word origin: Greek from the terms phyle/phylon (meaning "tribe, race,") and genetikos (meaning "relative to birth" from genesis ("birth").