LAUSR

Little is known about the extent to which species use homologous regulatory architectures to achieve phenotypic convergence. By characterizing chromatin accessibility and gene expression in developing wing tissues, we compared the regulatory architecture of convergence between a pair of mimetic butterfly species. Although a handful of color pattern genes are known to be involved in their convergence, our data suggest that different mutational paths underlie the integration of these genes into wing pattern development. This is supported by a large fraction of accessible chromatin being exclusive to each species, including the de novo lineage-specific evolution of a modular optix enhancer. These findings may be explained by a high level of developmental drift and evolutionary contingency that occurs during the independent evolution of mimicry. Description Same spots, different lots Convergent evolution is exemplified by two species presenting the same phenotype despite having different evolutionary trajectories. Van Belleghem et al. examined two pairs of butterfly species that overlap geographically and present nearly identical wing patterning to assess the conservation of gene expression and regulation. Although many of the same genes are involved in wing patterning in all four subspecies, they found that the underlying regulatory regions, represented by open chromatin over several developmental time points, were often not shared. They also identified a new enhancer in a single lineage and demonstrate its function through gene editing by CRISPR. —CNS Although nearly phenotypically identical, few regulatory regions are conserved between two pairs of butterfly species.