Fig. 2.

Phylogenetic distribution of Retinal Determination Gene Network (RDGN) homologs in an insect (Drosophila melanogaster), a non-arachnopulmonate arachnid group (Acariformes: Dinothrombium tinctorium; Tetranychus urticae) and Arachnopulmonata (spider: Parasteatoda tepidariorum; scorpion: Centruroides sculpturatus), including newly discovered orthologs in Charinus whip spiders (Amblypygi). Colored squares indicate number of paralogs for each RDGN gene. Dotted squares indicate presumed missing data, not gene loss. For comprehensive list of duplicated genes in Arachnopulmonata see Schwager et al. (2017) and Leite et al. 2018. Gene trees and alignments for each gene are available in Additional file 1 Dataset S1