Phylogram
A phylogram is a branching tree diagram that summarizes in graphic form the evolutionary history of a group of organisms.
The length of each branch stem indicates the amount of evolution, typically measured in a quantity like
number of nucleotide substitutions, that occured between the connected branch points.
In 1986, Michael M. Miyamoto and Morris Goodman published a phylogram showing the results of their
work in estimating the historical evolutionary relationships of a broad selection of eutherian
mammals.
Below is their published phylogram as drawn by
Phyloscope,
a JavaScript application developed at the
Berkeley Phylogenomics Group.
The horizontal lines in the tree are the stems that indicate the amount of evolution
along that branch. The spans, the vertical lines, serve only to connect an
ancestor to its immediate descendants. The length of the span has no special
significance.
A phylogram can be represented as a text string for transfer between software programs and
databases. The earliest general format for phylograms is the
Newick format,
based on the format originally developed in 1984 for the
PHYLIP
software package for inferring evolutionary trees. Below is the Miyamoto and Goodman
phylogram in Newick format that was used to draw this tree.
(Edentata:55, (((Orycteropus:12, Trichechus:43):1, (Procavia:29, (Elephas:18, Loxodonta:5):55):10):15, (((Chiroptera:27,
(Tupaia:43, ((Talpa:24, (Suncus:24, Erinaceus:58):6):4, (Manis:5, ((Felis:13, Leo:7):32, ((Canis:37, Ursidae:12):4,
((Phocidae:19, Zalophus:17):7, (Procyonidae:12, Mustelidae:22):9):5):17):13):3):10):6):8, (((Lemuridae:46,
(Galago:16, Nycticebus:27):10):8, (Tarsius:15, ((Cebus:10, (Atelinae:5, (Aotus:6, Callithrix:9):3):3):18,
((Hylobates:6, (Pongo:1, (Gorilla:2, (Homo:22, Pan:1):2):6):2):5, (Presbytis:1, (Cercopithecus:1, (Erythrocebus:0,
('Macaca fascicularis':2, ('Macaca mulatta':5, 'Macaca fuscata':0):1, (Theropithecus:2, Papio:4):15):2):1):8):6):9):22):10):13,
((Ochotona:7, Oryctolagus:54):4, (Caviomorpha:107, (Spermophilus:29, (Spalax:23, ((Rattus:71, Mus:19):15, (Ondatra:27,
Mesocricetus:32):27):20):8):12):15):11):9):12, ((Sus:50, ((Lama:10, Camelus:24):31, (Hippopotamus:31, (((Ovis:9, Capra:8):19,
((Antilocapra:13, Giraffa:14):7, (Cervus:8, Alces:9):11):2):9, (Tragelaphinae:6, ('Bos grunniens':6, (Bison:5,
'Bos taurus':15):7):11):6):47):10):19):18, ((('Equus (Asinus)':6, 'Equus caballus':31):24, (Tapirus:19,
Rhinocerotidae:23):11):22, ((Phocoena:4, Tursiops:17):5, (Balaenoptera:36, Eschrichtius:2):8):29):12):12):16):55);