Not trying to pull your thread off-topic, but here`s an approach:
A well-known paleontologist, Stephen J. Gould, had proposed that a better metaphor for the evolutionary history of earth’s life forms is a fuzzy bush not a tall bifurcating tree. Even so, Gogarten maintains that Gould’s metaphor does not sufficiently describe the pattern of microbial genomic exchange that has been emerging from his own research on HGT. According to Gogarten evolution corresponds neither to a tree nor a bush, but rather to a net in which lines of descent not only diverge but also communicate and even merge with one another.
and
Concluding his presentation, Gogarten brought attention to the metaphors biologists use to describe their work to the general public. Because the original metaphor of a tree no longer fits the data from recent genome research, Gogarten suggested that biologists use the metaphor of a mosaic to describe the different histories of combined in individual genomes and use a the metaphor of a net to visualize the rich exchange and cooperative effects of HGT among microbes
From;
http://www.esalenctr.org/display/confpage.cfm?confid=10&p...
Gogarten proposed this in 2000. Not sure how well it has been accepted.
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