A new index to find regions showing an unexpected variability or conservation in sequence alignments.

Present-day sequences are the result of long and complex pathways of evolution. Many of the features encoded in them are the result of a series of evolutionary processes, including selection, genetic drift, etc. Following this, protein families have a great amount of unexplored information that can be useful for many purposes beyond simple evolutionary studies. An index is presented here which permits the localization of regions showing an unexpected degree of variability or conservation. This index uses the information contained in sequence alignments and compares the observed over expected level of variability using tables for the relative likelihood of amino acid change.