Parsimony ancestral state reconstruction for the evolution of arthropod E(spl) complexes. Ancestral character states were inferred using parsimony analysis under an Mk1 model in Mesquite. Character states were mapped onto a cladogram representing the currently accepted phylogenetic relationships between insect species (Krauss et al. 2005; Robertson 2005; Savard et al. 2006). Reconstructions of the ancestral E(spl)-C are shown at the nodes and genes are color coded as for Figure 4. bHLH2 is absent from the Diptera, Tribolium, and Pediculus and the parsimony reconstruction is ambivalent as to whether the ancestral complex included bHLH2. However, we argue that the phylogenetic evidence (Fig. 2) precludes the re-evolution of bHLH2 from a duplication of bHLH1, and it is likely that bHLH2 has been lost independently. However, this uncertainty is represented by the dotted line surrounding bHLH2 in the diagrams.
