Why Names
- Unitat de Biologia Evolutiva, Universitat Pompeu Fabra, 08003 Barcelona, Catalonia, Spain
This extract was created in the absence of an abstract.
And Adam gave names to all cattle, and to the fowl of the air, and to every beast of the field.Genesis 2:20
Complexity and the Self-Similar Nature of Evolutionary Trees
Description may easily be a never-ending task if the amount of desirable detail is not specified beforehand. The endless complexity of nature is ingrained in the fractal geometry of organisms (such as corals) or their parts (such as lungs), but the fractal properties of the basic structure of life are also apparent in organelles, biochemistry, and genomes. That is why one of the most ubiquitous fractal shapes in nature, the tree, is used in many biological fields, and quite prominently in evolution. It allows the portrayal of the general shape of a branching process without reference to its most minute details. If a tree is constructed from the information in a genome segment, adding further information will sprout a new, self-similar tree, at the preexisting branches. This could proceed ad infinitum until all individual genomes have been sequenced in their entirety, and it would continue to grow in future generations.
Clearly, it is not the case that the more complexity, the better, and it seems that we should devise ways of extracting meaningful insights from what may become a dizzyingly complex tree. Here we suggest such a two-tiered strategy:
1. Fix a departing point in the past time where all extant variation coalesces for a species and a given genome region. Obviously, this past trunk was itself in the midst of a thicket, but all those other branches have become extinct and are irretrievable unless we study all past organisms.
2. From that departing point in the past, follow forward in time until the tree has grown to the desirable (manageable) bushiness or complexity. This level falls far short of the individual information that we have at the actual …
