Final answer:
The three domains represented in the phylogenetic tree of life are Bacteria, Archaea, and Eukarya. Bacteria and Archaea consist of prokaryotic life forms, while Eukarya comprises eukaryotic organisms with a defined nucleus.
Step-by-step explanation:
The phylogenetic tree of life, which categorizes all known life forms based on genetic relationships, includes three distinct domains: Bacteria, Archaea, and Eukarya. The domains Bacteria and Archaea comprise all prokaryotic organisms, which lack a nucleus. In contrast, Eukarya includes all eukaryotic organisms that maintain their genetic material within a nucleus and encompasses kingdoms such as plants, animals, fungi, and protists. The construction of such phylogenetic trees is rooted in the evolutionary relationships between organisms and often utilizes ribosomal RNA sequences to decipher genetic heritage and lineage connections.
The pioneering work of American microbiologist Carl Woese and his colleagues in the 1970s established the three-domain system as the new standard for phylogenetic classification, replacing the previously used five-kingdom system. Woese's findings also highlighted the surprising genetic affinity between members of the Archaea domain and the eukaryotic organisms of the Eukarya domain. Eukarya, including humans, appears to share a more recent common ancestor with Archaea than with Bacteria. This modern classification system reflects a more accurate depiction of life's diversity and evolutionary history.