Elision: a method for accommodating multiple molecular sequence alignments with alignment-ambiguous sites.

The process of multiple sequence alignment provides homology statements for the phylogenetic analysis of molecular data. Unfortunately, multiple alignments are frequently nonunique. Two sources of these multiple alignments are analysis based on different sets of alignment parameter values (gap:change cost ratios) and nonunique equally costly alignments based on a single set of alignment parameters. By "eliding" these individual alignments into a single grand alignment, phylogeny that is weighted toward those positions that align more consistently can be reconstructed. Positions that show greater variation among alignments will be relatively downweighted. The technique results in a weighting procedure that is a posteriori and based on the evidence established from the original sequence alignments.