Butterfly eyespots evolved via co-option of the antennal gene-regulatory network

Abstract

AbstractButterfly eyespots are beautiful novel traits with an unknown developmental origin. Here we show that eyespots likely originated via co-option of the antennal gene-regulatory network (GRN) to novel locations on the wing. Using comparative transcriptome analysis, we show that eyespots cluster with antennae relative to multiple other tissues. Furthermore, three genes essential for eyespot development (Distal-less(Dll),spalt(sal), andAntennapedia(Antp)) share similar regulatory connections as those observed in the antennal GRN. CRISPR knockout ofcis-regulatory elements (CREs) forDllandsalled to the loss of eyespots and antennae, and also legs and wings, demonstrating that these CREs are highly pleiotropic. We conclude that eyespots likely re-used the ancient antennal GRN, a network previously implicated also in the development of legs and wings.