Effects of Gap Open and Gap Extension Penalties

Fundamental to multiple sequence alignment algorithms is modeling insertions and deletions (gaps). The most prevalent model is to use gap open and gap extension penalties. While gap open and gap extension penalties are well understood conceptually, their effects on multiple sequence alignment, and consequently on phylogeny scores are not as well understood. We use exhaustive phylogeny searching to explore the effects of varying the gap open and gap extension penalties for three nuclear ribosomal data sets. Particular attention is given to optimal phylogeny scores for 200 alignments of a range of gap open and gap extension penalties and their respective distribution of phylogeny scores.