Final answer:
The "tree of life" analogy does not fully account for horizontal gene transfer, leading some to prefer the "web of life" concept. Modern taxonomy uses genetic analysis to determine relationships, but the classic tree model may need revision to better represent evolutionary complexities.
Step-by-step explanation:
The branching "tree of life" analogy has traditionally been used to describe evolutionary relationships among species, with all branches originating from a single trunk. However, this model is challenged by the concept of horizontal gene transfer (HGT), where genes are exchanged between species, which can make it difficult to determine how organisms are evolutionarily related.
As a result, some scientists now think in terms of "webs of life" rather than "trees of life" because this concept better accounts for these complex interactions and gene exchanges.
In modern taxonomy, scientists determine how closely two organisms are related by analyzing their RNA, DNA, and proteins. The understanding is that all organisms represented in the tree of life are related to a single ancestral lineage. However, a lineage does not evolve entirely independently once a split occurs because of the possibility of horizontal gene transfer.
The need to revise the classic tree model arises from the acknowledgment of HGT and genomic fusion, which are not well represented in a bifurcating tree structure. Alternative models like the "web of life" or the "ring of life" have been proposed. These models serve as hypotheses that can be tested with new data and research.