Bayesian mimicry in the non-rewarding saprophytic orchid Danxiaorchis yangii

<p>Bayesian mimicry, a type of deceptive pollination, is a complicated strategy used by non-rewarding plants to attract pollinators, but some hypotheses concerning this phenomenon have not been systematically verified. In order to show in detail a case of Bayesian mimicry on saprophytic orchid <i><span>Danxiaorchis yangii</span></i> in this study, we compared floral characteristics of <i><span>Danxiaorchis yangii </span></i>and <i><span>Lysimachia alfredi </span></i>as well as the pollination behavior of the insect <i><span>Dufourea </span></i>sp<i><span>.</span></i> towards the two species<i><span>. Lysimachia alfredi</span></i> can provide a reward to <i><span>Dufourea</span></i> sp., whereas <i><span>Danxiaorchis yangii </span></i>cannot<i><span>. </span></i>The flowering phenology and geographical distribution of these two plants are highly overlapping. Statistical analysis of quadrat and <i><span>L. alfredi</span></i> transplanting test data revealed that the fruit set rate of <i><span>Danxiaorchis yangii </span></i>was significantly positively correlated with the number of nearby <i><span>L. alfredi </span></i>individuals. In a glass cylinder experiment, <i><span>Danxiaorchis yangii </span></i>and <i><span>L. alfredi </span></i>attracted <i><span>Dufourea </span></i>sp. through visual signals, but the insect could not distinguish between flowers of the two plants before landing on flowers. We observed that the ultraviolet reflection spectra of <i><span>Danxiaorchis yangii </span></i>and <i><span>L. alfredi </span></i>are highly similar. In addition, we found that the hexagonal color models of the two plants are consistent with the bee's visual characteristics, thus indicating that the visual signals of the flowers of the two plants are greatly similar. All of these results provide evidence that <i><span>Danxiaorchis yangii </span></i>simulates the visual signals of <i><span>L. alfredi</span></i> through <span class="15"><span>Batesian </span></span>mimicry, thereby deceivingly attracting <i><span>Dufourea </span></i>sp.</p>