Unrooted trees can be inferred by chromosomal inversions.

The phylogeny of one subgroup of the Hawaiian fruitflies is better known than that of any other equivalently large group of living creatures. It was worked out, by Carson and his colleagues, from chromosomal banding patterns which are clearly visible in fruitflies such as Drosophila melancia , opposite.

The banding patterns differ between species, and it soon becomes obvious that regions of the chromosomes have been inverted during evolution: a segment of genes within a chromosome has been inverted as a whole.

Using knowledge of chromosomal inversions, the unrooted tree of the fruitflies could be inferred. The following animation makes clear how this is possible.