Answer:
- revealed that rRNA is highly conserved so can be used for classification
- have led to the development of a new taxonomic system divided into domains
Explanation:
The ribosomal RNA (rRNA) genes are widely used in evolutionary, phylogenetic, and phylogeographic studies as molecular markers because they represent nuclear genes that are highly conserved between species. However, it is important to highlight that rRNA genes form arrays at specific chromosomal sites, thereby they often exhibit pseudogenes that may interfere with their use as molecular markers (i.e., they produce multiple bands in the electrophoresis gel). In 1977, Carl Woese showed that Archaea is an evolutionary lineage separated from Bacteria by using molecular evidence based on an rRNA molecular marker (16S rRNA). Thus, Woese indicated that Eukarya, Bacteria and Archaea represent three different domains that arose separately from an evolutionary ancestor named 'progenote'.