**Distance based methods:** Minimize the number of global changes
between each pair in a group of sequences previously aligned.

**Least squares approach**:
From a matrix of distances *D* between species, find a phylogenetic tree
that predicts a set of distances *d* so that the following expression is
minimized:

**Neighbour-joining**:

- Join the clusters that are close to another and also apart from the rest
**Heuristic:** Minimize the sum of the branch lengths in the tree
- Additivity of evolutionary distances