Division of Evolutionary Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.
Smithsonian Tropical Research Institute, Gamboa, Panamá.
J Evol Biol. 2024 Mar 1;37(3):267-273. doi: 10.1093/jeb/voae010.
Traits under divergent ecological selection that also function during mating can be important in maintaining species boundaries. Few studies have considered mutual mate choice, where both males and females base mating decisions on the same trait. Wing colouration in Heliconius butterflies evolved as a warning signal but also functions as a mating cue. We investigated the contribution of visual preference to assortative mating in an aposematic butterfly Heliconius cydno in the context of reproductive isolation with its sympatric, visually distinct relative Heliconius melpomene. Heliconius cydno have conspicuous white bands on their forewings, whereas those of H. melpomene are red in colour. We predicted that both sexes of H. cydno contributed to assortative mating by exhibiting visual preference towards conspecific wing colouration. We analysed published and new data from preference experiments, in which males were presented with conspecific and H. melpomene females. We also recorded female responses and mating outcomes in choice experiments, involving conspecific males with either the original white or artificially painted red forewing bands. Both sexes of H. cydno responded more positively towards the conspecific colouration, and males strongly preferred females of its own colours. In contrast, male colouration did not predict mating outcomes in female choice experiments. As courtships are initiated by males in butterflies, our findings suggest that female visual preference might be of secondary importance in H. cydno. Our data also suggest that the contribution of visual preference to reproductive isolation might be unequal between H. cydno and its sympatric relative H. melpomene.
在不同生态选择下发挥作用的特征，如果也在交配过程中发挥作用，则可能对维持物种边界很重要。很少有研究考虑过相互的配偶选择，即雄性和雌性都根据相同的特征做出交配决定。在凤蝶中，翅膀颜色的进化既是一种警告信号，也是一种交配线索。我们在与同域的、视觉上明显不同的 Heliconius melpomene 存在生殖隔离的情况下，研究了具有警戒作用的蝴蝶 Heliconius cydno 中视觉偏好对交配的影响。Heliconius cydno 的前翅有明显的白色条纹，而 H. melpomene 的前翅则是红色的。我们预测，Heliconius cydno 的雌雄两性都通过对同种翅膀颜色表现出视觉偏好来促进交配的选择性。我们分析了偏好实验的已发表和新数据，在这些实验中，雄性被展示了同种和 H. melpomene 的雌性。我们还在涉及具有原始白色或人工绘制的红色前翅条纹的同种雄性的选择实验中记录了雌性的反应和交配结果。Heliconius cydno 的雌雄两性对同种颜色的反应更为积极，雄性强烈偏好自己颜色的雌性。相比之下，雄性颜色并不能预测雌性在选择实验中的交配结果。由于蝴蝶中的求偶行为是由雄性发起的，我们的发现表明，在 Heliconius cydno 中，雌性的视觉偏好可能是次要的。我们的数据还表明，视觉偏好对生殖隔离的贡献在 Heliconius cydno 和它的同域近亲 H. melpomene 之间可能是不平等的。
