How do I calculate branch length on a phylogenetic tree?

[0ochello0]

Hi,

I'm trying to calculate the phylogenetic tree branch lengths for some kingfisher species, but I can't seem to find any information on how to do it.

 

Here is the tree I am looking at KINGFISHERS

 

so if i were to calculate the branch length for Alcedo azurea (the 6th from the top), what do I need to do? What would the branch length for this kingfisher be? Once I have one, I should be able to work out the rest.

 

Thanks!

[CharonY]

Check the scale at the bottom and use that to measure distance (and then convert it into substitutions/site).

[0ochello0]

Check the scale at the bottom and use that to measure distance (and then convert it into substitutions/site).

 

Thanks,

This might be a silly question but do I measure all of the lines (horizontal and vertical) in the tree to get to the species I want? Or just the horizontal?

 

So I measured everything for Alcedo azurea and come up with 0.1073 substitutions per site, is that the value for the branch length?

 

I'm trying to put some branches of the tree into Newick format, so far i've worked out the code for the tree, now I just need to learn how to calculate the branch lengths to make it more accurate..

[0ochello0]

anyone? please?

sorry to pester, I assume its pretty basic stuff but I can't seem to find anything published on how to do it...

[CharonY]

It depends on how it is drawn, but in square representations the horizontal length represents the node distance. The vertical line is just there for visual reasons (in other representations it is actually absent).