Astral v.5.6.2 the resulting species tree has some branch lengths are negative · Issue #37 · smirarab/ASTRAL (original) (raw)

I use 91 gene tree to produce a species tree, and with this one, I would compare the difference between contenation and coalascence.
when I imported this species tree into R, wanting to transfer it to ultrametric format, but there are some output error for this tree. there it is:

I checked this tree, no found any negative value. How to explain this? Is it a bug for Astral?