Small DNA analysis tool. SLR (Sitewise Likehood Ratio estimation of selection) is a program to detect sites in coding DNA that are unusually conserved and/or unusually variable (that is, evolving under purify or positive selection) by analysing the pattern of changes for an alignment of sequences on an evolutionary tree. The strength of selection at each site is determined by comparing the rate of nonsynonymous (amino acid changing) substitutions to that of synonymous (silent) substituions, the latter assumed to be invisible to selection and so evolving in a strictly neutral fashion.

SLR performs an explicit likelihood-ratio test for selection at each site in the alignment, making few assumptions about the distribution of selection and potentially allowing every site to be under a different level of evolutionary constraint. SLR is a direct test of whether a particular site is evolving in a non-neutral fashion; the many sitewise tests are then corrected for multiple comparisons to indicate which sites have strong evidence of purifying or positive selection and so whether there is any reliable evidence for the presence of selection in the alignment. Alternatively SLR can restricted to only detect unusually variable sites, indicating such sites and providing evidence for the presence of positive selection in the alignment.

The license of this software is Free, you can free download and free use this calculator software.