sentence: In LRT A ( Additional file 12 ) we compare : i ) A model that assumes an overall d / d rate ratio for all branches in the tree ( omega 1 ) and a different rate for the branch that is ancestral to the ‘ glabrata group ’ ( omega 2 ) , where we hypothesize a rate acceleration ; and ii ) an alternative model that assumes one d / d ratio for the basal branches including S. cerevisiae , C. castellii and N. bacillisporus ( omega 1 ) , a different d / d rate in the branch ancestral to the ‘ glabrata group ’ ( omega 2 ) , and another d / d rate for the genus itself ( omega 3 ) .