I have written about sequence conservation in vertebrates previously but without much elaboration, hence I'm writing another post on this topic. An assumption of sequence conservation is that regions that show conservation, are under purifying selection, i.e. alleles that decrease the fitness of an organism are removed, and therefore probably do something important. Protein-coding regions are typically well conserved among the genomes of different species, so it's widely accepted that they are useful. Sequences need to be aligned together in order to infer sequence conservation and conveniently, a multiple sequence alignment (MSA) of 46 vertebrate genomes is provided at the UCSC Genome Browser site.