External transcribed spacer (ETS) refers to a piece of non-functional RNA, closely related to the

internal transcribed spacer Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. I ...

, which is situated outside structural ribosomal RNAs (rRNA) on a common precursor transcript. ETS sequences characteristic to an organism can be used to trace its

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spe ...

References

{{genetics-stub DNA Phylogenetics de:Spacer (Biologie)