 Dear students in this module will review what we studied in the chapter of phylogenetics or molecular evolution. So the important concepts that were delivered included molecular evolution itself wherein sequences, the proteins or DNA, these sequences evolve over time and they change. So these changes can happen by three different mechanisms, insertions, deletions and substitutions. So once these three mechanisms kick in the sequences they start diverging and speciation and other such events they occur. So in order to study such variation in species then we can construct phylogenetic trees or simple relationship trees wherein we can see the distance between various species. So there were two types of trees, the scaled and the unscaled trees. So in the scaled trees we can obviously see how far the various species are from each other in terms of evolution and time while the unscaled trees do not show us this information. Also we looked at the molecular clock. So the edge length in a phylogenetic tree represented the length of this edge it represented the time it has taken to evolve while with the clock the lengths of these branches were equal. So the rate of evolution is different and therefore you may want to go without a clock. Also the phylogenetic trees included rooted and unrooted trees. So for the unrooted trees there was no parent for the siblings or the children while in the rooted trees there is always an ancestor and the remaining children are lower than the ancestor. So UPGMA was an algorithm that we studied in detail and it meant unweighted pair group method using arithmetic averages and it helped us to compute phylogenetic trees such that they were rooted and had an ancestor. So in conclusion in this course we have discussed clustering based strategies only and for the clustering based strategies we have studied the UPGMA algorithm while there are other non clustering strategies that are available for phylogenetic studies as well. So these include methods such as maximum parsimony which are not included in this course.