Butterfly wing patterns provide a rich comparative framework to study how morphological complexity develops and evolves. Here we used CRISPR/Cas9 somatic mutagenesis to test a patterning role for WntA, a signaling ligand gene previously identified as a hotspot of shape-tuning alleles involved in wing mimicry. We show that WntA loss-of-function causes multiple modifications of pattern elements in seven nymphalid butterfly species. In three butterflies with a conserved wing-pattern arrangement, WntA is necessary for the induction of stripe-like patterns known as symmetry systems and acquired a novel eyespot activator role specific to Vanessa forewings. In two Heliconius species, WntA specifies the boundaries between melanic fields and the light-color patterns that they contour. In the passionvine butterfly Agraulis, WntA removal shows opposite effects on adjacent pattern elements, revealing a dual role across the wing field. Finally, WntA acquired a divergent role in the patterning of interveinous patterns in the monarch, a basal nymphalid butterfly that lacks stripe-like symmetry systems. These results identify WntA as an instructive signal for the prepatterning of a biological system of exuberant diversity and illustrate how shifts in the deployment and effects of a single developmental gene underlie morphological change.
Mazo-Vargas, AnyiConcha, CarolinaLivraghi, LucaMassardo, DarliWallbank, Richard W.R.Zhang, LinlinPapador, Joseph D.Martinez-Najera, DanielJiggins, Chris D.Kronforst, Marcus R.Breuker, Casper J.Reed, Robert D.Patel, Nipam H.McMillan, W. OwenMartin, Arnaud
Faculty of Health and Life Sciences\Department of Biological and Medical Sciences
Year of publication: 2017Date of RADAR deposit: 2017-09-26