Final answer:
Phylogenetics deals with the issue of distinguishing homoplasy (convergent evolution) from homology (traits inherited from a common ancestor). Calculations can be misled by rapid evolution, possibly misplacing taxa as outgroups. Phylogenetic trees, guided by the principle of maximum parsimony, may require careful interpretation and adjustment in these cases.
Step-by-step explanation:
The question addresses a common issue in phylogenetics, which is the distinction between homoplasy and homology. Calculations based on morphological or molecular data can indeed struggle to differentiate between these two phenomena. Homoplasy, also known as convergent evolution, occurs when species develop similar features independently, often due to similar environmental pressures, rather than from a common ancestor. On the other hand, homology refers to traits that are inherited from a common ancestor. The issue with faster evolving taxa is that they may accumulate many changes quickly, and thus appear to be more distantly related—potentially being wrongly identified as an 'outgroup'—even if this is not the case from an evolutionary perspective.
Phylogenetic trees are constructed using a principle known as maximum parsimony, which assumes that the tree with the least complex explanation, involving the fewest evolutionary changes, is the most likely to be correct. However, when faced with species that have evolved rapidly, this principle can misplace them on the phylogenetic tree if care is not taken to properly identify the nature of the similarities used to construct the tree.