Final answer:
Modern systematics integrates phylogeny and taxonomy to focus on evolutionary relationships and not just classification. Systematists use a variety of data to construct phylogenetic trees, which represent hypotheses of evolutionary history and are updated with new information.
Step-by-step explanation:
Among the statements regarding systematics and its subdisciplines, the one that is true is that modern systematics is focused on determining evolutionary relationships, not just classifying organisms. The field of systematics is where scientists use combined data based on evolutionary relationships from various sources, including fossils, morphological structures, molecules, and DNA analysis, to construct the phylogeny of an organism. In essence, it integrates both phylogeny and taxonomy.
Systematics is the science of classifying organisms, with the goal of organizing and classifying organisms based on evolutionary relationships. Taxonomy, a subdiscipline of systematics, provides a hierarchical system to group organisms. Different levels of this taxonomic system, such as domain, kingdom, phylum, class, order, family, genus, and species, help scientists categorize living organisms.
To determine valid evolutionary taxa, systematists must indeed use both phylogeny and taxonomy jointly. Phylogenetic trees, which are hypotheses about the evolutionary pathways of species, are based on phylogenetic data and not just taxonomy. These trees are constantly updated as new information becomes available, providing a dynamic view of the evolutionary history of life on Earth.