The inference of phylogenetic relationships from molecular data is contributing greatly in understanding the evolution of life on Earth. Although the discussion that follows is directed toward analyses based on rRNA sequences, nearly all of the concepts, and many of the details, are equally applicable to the other DNA, RNA, or protein sequences. The analysis of sequences also helps to ensure that the evolutionary inferences are based on homologous features; the interspersion of conserved with more variable sequences permits the more slowly changing sequence features to provide landmarks for identifying homologous positions in adjacent, more variable, sequences. Finally, sequence data accumulate and are constantly available for further comparisons and analyses. This contrasts with types of data that require pairwise laboratory comparisons of all the species considered. In essence, the value of a sequence increases as data from additional organisms and molecules become available. Preexisting sequences provide a framework within which new sequence data can be analyzed. The availability of sequences of homologous molecules from many species is one of the greatest assets of rRNA-based phylogenies.
ASJC Scopus subject areas
- Molecular Biology