Question

It is often desirable to define the root of a tree. There are two ways to define the root of a tree. One is to use an outgroup, which ______

(a) is a sequence that is homologous to the sequences under consideration

(b) is separated from those sequences at an early evolutionary time

(c) is generally determined from independent sources of information

(d) is generally determined from similar or related sources of information

The question was asked in examination.

My question is based upon Gene Phylogeny Versus Species Phylogeny in portion Molecular Phylogenetics of Bioinformatics

Answer 1

Right option is (d) is generally determined from similar or related sources of information

For explanation I would say: Here, the option “is generally determined from independent sources of information” and contradict and it can be explained as follows. For example, a bird sequence can be used as a root for the phylogenetic analysis of mammals based on multiple lines of evidence that indicate that birds branched off prior to all mammalian taxa in the in group. Outgroups are required to be distinct from the in group sequences, but not too distant from the in group.