Mating preferences act independently on different elements of visual signals in Heliconius butterflies

• Published in: Behavioral ecology 2024-09, Vol.35 (5)
• Main Authors: Smith, Sophie Helen, Queste, Lucie M, Wright, Daniel Shane, Bacquet, Caroline Nicole, Merrill, Richard M
• Format: Article
• Language: English
• ISSN: 1045-2249; 1465-7279
• DOI: 10.1093/beheco/arae056

Abstract Mating cues are often comprised of several elements, which can act independently, or in concert to attract a suitable partner. Individual elements may also function in other contexts, such as anti-predator defense or camouflage. In Heliconius butterflies, wing patterns comprise several individual color pattern elements, which advertise the butterflies’ toxicity to predators. These wing patterns are also mating cues and males predominantly court females that possess the same wing pattern as their own. However, it is not known whether male preference is based on the full wing pattern or only individual pattern elements. We compared preferences of male H. erato lativitta between female models with the full wing pattern and those with some pattern elements removed. We found no differences in preference between the full wing pattern model and a model with pattern elements removed, indicating that the complete composition of all elements is not essential to the mating signal. Wing pattern preferences also contribute to pre-mating isolation between two other Heliconius taxa, H. erato cyrbia, and H. himera; therefore, we next compared preferences for the same models in these species. H. erato cyrbia and H. himera strongly differed in preferences for the models, potentially providing a mechanism for how pre-mating isolation acts between these species. These findings suggest that contrasting levels of selective constraint act on elements across the wing pattern. Heliconius butterflies are well known for their bright warning patterns, which they also use to recognize potential mates. We show that these mating decisions are based on only some parts of these warning patterns. This may enable local adaptation, as males can use only a small part of the wing pattern to choose a mate, while the rest of the wing can adapt to the pressures of the environment.