Data for: Ebony underpins Batesian mimicry in melanic stoneflies

<p><span>The evolution of Batesian mimicry – whereby harmless species avoid predation through their resemblance to harmful species – has long intrigued biologists. In rare cases, Batesian mimicry is linked to intraspecific colour variation, in which only some individuals within a population resemble a noxious 'model'. Here, we assess intraspecific colour variation within a widespread New Zealand stonefly, wherein highly melanised individuals of <em>Zelandoperla</em> closely resemble a chemically defended aposematic stonefly, <em>Austroperla</em> <em>cyrene</em>. We assess convergence in the colour pattern of these two species, compare their relative palatability to predators, and use genome-wide association mapping to assess the genetic basis of this resemblance. Our analysis reveals that melanised <em>Zelandoperla </em>overlap significantly with <em>Austroperla</em> in colour space, but are significantly more palatable to predators, implying that they are indeed Batesian mimics. Analysis of 194,773 genome-wide SNPs reveals an outlier locus (<em>ebony</em>) strongly differentiating melanic versus non-melanic <em>Zelandoperla</em>. Genotyping of 338 specimens from a single <em>Zelandoperla</em> population indicates that <em>ebony</em> explains nearly 70% of the observed variance in melanism. As <em>ebony</em> has a well-documented role in insect melanin biosynthesis, our findings indicate this locus has a conserved function across deeply divergent hexapod lineages. Distributional records suggest a link between the occurrence of melanic <em>Zelandoperla</em> and the forested ecosystems where the model <em>Austroperla</em> is abundant, suggesting the potential for adaptive shifts in this system underpinned by environmental change.</span></p>