Final answer:
Molecular data is often more helpful in discovering relationships among closely and distantly related species and is more effective in determining phylogeny. They use computer programs and compare phylogenetic trees using different sequences to build confidence in the inferred relationships.
Step-by-step explanation:
Molecular data is often more helpful in discovering relationships among very closely or very distantly related species. Computer programs help determine relatedness using DNA sequencing, and morphologic and molecular information is more effective in determining phylogeny. By comparing phylogenetic trees using different sequences and finding them similar, scientists can build confidence in the inferred relationships.