There are two ways of finding the root of a phylogenetic tree. The first is to include one or more sequences in the data set that are known to lie outside the diversity of the sequences of interest. These sequences are usually referred to as the 'outgroup'.For example, in the trees above, the pair of tips labelled 'virus9' and 'virus10' could be the outgroup allowing us to root the tree at the red circle.hese sequences are usually referred to as the 'outgroup'. For example, in the trees above, the pair of tips labelled 'virus9' and 'virus10' could be the outgroup allowing us to root the tree at the red circle.
The origin of the prefix anti- and its variant ant- is an ancient Greek word which meant âagainstâ or âopposite.â These prefixes appear in numerous English vocabulary words, such as antifreeze, antidote, antonym, and antacid.
Updated May 05, 2017. In English grammar and morphology, a prefix is a letter or group of letters attached to the beginning of a word that partly indicates its meaning, including such as examples as anti- to mean against, co- to mean with, mis- to mean wrong or bad, and trans- to mean across.