Evolutionary events leading to the extant chordate <i>Dlx</i> gene family.

<p>Phylogenetic relationships between chordate <i>Dlx</i> gene family members including: the single amphioxus Amphi-Dll gene <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068182#pone.0068182-Holland1" target="_blank">[36]</a>; the three <i>Ciona Dlx</i> genes: <i>Ciona-DllA</i> and <i>Ciona-DllB</i> forming a bigene cluster and single <i>Ciona-DllC </i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068182#pone.0068182-Caracciolo1" target="_blank">[35]</a>; six <i>Dlx</i> genes from the mouse (<i>Mus musculus</i>, noted <i>Mm</i>) and catshark (<i>Scyliorhinus canicula</i>, noted <i>Sc</i>) organized as three bigene clusters: <i>Dlx1</i>–<i>Dlx2</i>, <i>Dlx3</i>–<i>Dlx4</i>, <i>Dlx5</i>–<i>Dlx6</i>. Zebrafish <i>dlx</i> genes are figured as three bigene clusters plus additional single genes (originating from the teleost-specific whole genome duplication): <i>dlx1a</i>-<i>dlx2a</i> plus <i>dlx2b</i>, <i>dlx3b</i>-<i>dlx4b</i> plus <i>dlx4a</i>, <i>dlx5a</i>-<i>dlx6a</i>. The first tandem duplication is mapped as a brown square (TD), the two vertebrate rounds of genome duplication are mapped as yellow squares annotated R1 and R2, the grey dashed line separates an early phase of <i>Dlx</i> paralog divergence before gnathostome diversification from the later phase occurring during gnathostome lineages divergence.