Fig. 2From: Glass confers rhabdomeric photoreceptor identity in Drosophila, but not across all metazoansGlass homologues exist in most animal groups. Based on sequence comparison (Additional file 4, also see Fig. 3), we infer that glass appeared in the common ancestor of all metazoans, and that it has been transmitted to most present-day animals (shown in green on the phylogenetic tree [74]). However, we were not able to identify glass in vertebratesBack to article page