What is the Tree of Life? What is the Tree
of Life? The tree of life is a graphical representation of the
evolutionary relationship (phylogenetic relationships) between all
forms of life that we know to exist on earth. Knowing an organism's
phylogeny helps us understand how related one organism is to another.
The Tree of Life gives us a visual image of organism relatedness,
by depicting a variety of organisms whose position in the tree corresponds
to their relatedness to other organisms within the tree. As on a
road map, the fewer turns you make, and the less distance you need
to travel, the closer you are to your destination. This is the case
for organisms on the Tree of Life, as well. For instance, Giardia
is located near the center of the tree (just below the label "0.1
changes per site"). The archaeon Methanopyrus is also located
very close to the axis of the tree. By their relative positions,
we can deduce that Methanopyrus and Giardia are closer
relatives than the Flavobacterium (located near the very
end of the Bacterial "road") and Cryptomonas (located near
the end of the Eucarya "road"). The
Tree of Life Web Project is an interesting site that discusses
of the nuances of determining phylogeny.