  We consider character sequences evolving on a phylogenetic tree under the
TKF91 model. We show that as the sequence lengths tend to infinity the the
topology of the phylogenetic tree and the edge lengths are determined by any
one of (a) the alignment of sequences (b) the collection of sequence lengths.
We also show that the probability of any homology structure on a collection of
sequences related by a TKF91 process on a tree is independent of the root
location.
  Keywords: phylogenetics, DNA sequence evolution models, identifiability,
alignment
