deletions | additions       diff --git a/General notes on bacterial systematics.md b/General notes on bacterial systematics.md  index a3da6cc..36ffc5b 100644  --- a/General notes on bacterial systematics.md  +++ b/General notes on bacterial systematics.md 
...
#A brief introduction to phylogeny and systematics.  In order to identify to which organism a 16S rDNA sequence belongs, as well as to provide an evolutionary context for your organism of interest, we recommend building inferring  a phylogenetic tree comparing the new 16S sequence to other 16S sequences  (see Section 11). Building the such a  phylogenetic tree is (relatively speaking)  the easy part. Intelligent interpretation of the tree will require an investment of time, similar to the investment required to learn the basics of UNIX. Fortunately, there are a number of resources available for this purpose. We recommend this online tutorial (http://evolution.berkeley.edu/evolibrary/article/phylogenetics_02) (http://evolution.berkeley.edu/evolibrary/article/phylogenetics_02)(ADD A REAL CITATION HERE IF POSSIBLE)  or this paper by Baldauf (ADD A REAL CITATION HERE)  http://research.cs.queensu.ca/home/cisc875/faint.pdf. Here we provide a brief introduction to phylogenetic trees. A phylogenetic tree is a diagram representing a model of evolutionary relationships. Phylogenetic trees have three main components: taxa, branches, and nodes. These are defined below:  * ***Taxon***. An individual or grouping of individuals. This could be individual sequences, species, families, phyla, etc. For phylogenetic analyses analyses, the  taxa that  are drawn at the tips of branchesand thus  are sometimes referred to as "leaves" on the tree. * ***Branch*** A representation of the evolution of a taxon over time (sometimes also known as an evolutionary lineage). There are three main types of branches in a tree. Terminal branches are those that lead to the tips or leaves in the tree. Internal branches connect branches to each other. And the root branch, also known as the root of the tree, is the branch that leads from the base of the tree to the first node in the tree.