What do we call the study of evolutionary relationships and lineage through a phylogenetic tree?

The study of evolutionary relationships and lineage represented through a phylogenetic tree is most accurately described as "evolutionary biology." This field encompasses various aspects of evolution, including the mechanisms of natural selection, genetic drift, and speciation, and it often utilizes phylogenetic trees to visualize the connections between different species based on their evolutionary history.

Phylogenetic trees reflect these evolutionary relationships by mapping out how various species are related to one another, often based on shared traits or genetic information. While "cladistics" also deals with evolutionary relationships, it specifically focuses on grouping organisms based on common ancestry and derived characteristics rather than the broader study of evolution itself. "Taxonomy" refers more to the classification and naming of organisms and does not inherently involve the evolutionary relationships represented in phylogenetic trees. "Phylogenomics," on the other hand, is a subfield that specifically uses genomic data to infer evolutionary relationships but is not as general as evolutionary biology.

In summary, evolutionary biology encompasses the broader investigation of evolution and the relationships depicted by phylogenetic trees, making it the most appropriate choice in this context.