Evolution in <i>lin-3 cis</i>-element requirement does not result from a modified <i>trans</i> environment.

<p><b>(A)</b> Transcriptional <i>lin-3-CRM</i>::<i>Cherry</i> fusions from different <i>Caenorhabditis</i> species are all expressed in the anchor cell of <i>C</i>. <i>elegans</i>. <b>(B)</b> A <i>Can-lin-3</i> single-copy transgene is expressed in the <i>C</i>. <i>elegans</i> anchor cell. smFISH detection of <i>Can-lin-3</i> in <i>C</i>. <i>elegans</i> strain harbouring a single extra-copy of <i>Can-lin-3</i>. Green spots correspond to <i>lin-3</i> expression, while blue is DAPI staining. <b>(C)</b> A single extra-copy of <i>Can-lin-3</i> fully rescues vulval induction of the <i>Cel-lin-3(e1417)</i> mutant to wild-type levels, both when homozygous (two copies, n = 100) or when hemizygous (one copy, n = 30). See the corresponding brood size rescue results in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1006278#pgen.1006278.s008" target="_blank">S8 Fig</a>.