|
Molecular phylogeny is the use of a gene's molecular characteristics to classify an organism and to place it
on a map of evolutionary relationships known as the phylogenetic
tree.
Every living organism is composed of certain substances such as DNA, RNA, and proteins. Closely related organisms generally have a high degree of agreement in the molecular structure of
these substances, while the molecules of organisms distantly related usually show
a pattern of dissimilarity. Molecular phylogeny uses such data to build a "relationship tree" that shows the probable evolution of various organisms. Not until recent decades, however, has it been possible
to isolate and identify these molecular structures. That it is now possible to do so can be seen by the ever more popular use of
genetic testing to determine a child's paternity, as well as the emergence of a new branch of criminal forensics focused on genetic evidence.
The effect on traditional scientific
classification schemes in the biological sciences has been dramatic as well. Work that was once immensely labor- and
materials-intensive can now be done quickly and easily. As a result many branches of the phylogenetic tree have been disassembled
and reassembled into patterns based on molecular identification rather than on the previous system of taxonomy based on morphology.
Because it is now possible to infer a gene's relationships by the existence of molecular similarities between it and other
genes, it is also possible to use that information to determine the relationships of organisms based on the presence or absence,
and the DNA sequence, of various genes.
See also: phylogeny - molecular evolution
External links
|