| |
| | Phylogenetics Factsheet |
 | | Phylogenetic systematics is that field of biology that does deal with identifying and understanding the evolutionary relationships among the many different kinds of life on earth, both living (extant) and dead (extinct). |
 | | A phylogenetic tree is composed of nodes, each representing a taxonomic unit (species, populations, individuals), and branches, which define the relationship between the taxonomic units in terms of descent and ancestry. |
 | | Branches on phylogenetic trees may be scaled (top panel) representing the amount of evolutionary change, time, or both, when there is a molecular clock, or they may be unscaled (middle panel) and have no direct correspondence with either time or amount of evolutionary change. |
| www.ncbi.nlm.nih.gov /About/primer/phylo.html (5910 words) |
|