Abstract: Floral traits associated with reward quality information are often subject to pollinator preference and selection, the evolutionary potential of which would be reflected by genetic variation and genetic correlation. Pedicularis has a variety of corolla types, which are widely distributed in the Qinghai-Tibet Plateau. The evolution of Pedicularis has been shown to be closely related to pollinator selection. In this study, the heritability of flower attraction traits and rewards (pollen and nectar) and the size of genetic correlation between them were analyzed by quantitative genetic experiments using nectarless Pedicularis semitorta and nectar-containing P. kansuensis distributed along the eastern margin of the Qinghai-Tibet Plateau. The results showed that the heritability of flower height, flower size, and pollen quantity in P. semitorta was high, but the heritability of inflorescence number and flower number was low. In P. kansuensis, the heritability of flower height, helmet height, and sugar content was higher, while the heritability of flower size, inflorescence number, flower number, sugar concentration and nectar content was lower. There was no significant correlation between pollen quantity and flower traits in P. semitorta, suggesting that flower attraction traits do not reflect their reward amount. There was a significantly positive phenotypic correlation between sugar concentration and inflorescence number, flower number in P. kansuensis, but the genetic correlation was not significant. Nectar content had a significantly positive phenotypic correlation with flower size, flower height, and flower number, while nectar content had a significantly positive genetic correlation with flower size and height. The phenotypic and genetic correlation between sugar content and the measured floral traits were all significantly positive. Those results suggest that multiple floral traits can serve as honest signals of reward in P. kansuensis. The size of phenotypic and genetic correlations between floral traits and reward in P. kansuensis was significantly higher than that in P. semitorta. This may be related to the evolution of corolla morphology in Pedicularis. The stronger genetic correlation may limit the independent evolution of floral traits and reward in P. kansuensis, while the floral traits in P. semitorta have a higher potential for independent evolution. This study contributes to a better understanding of the formation and maintenance of plant diversity on the Qinghai-Tibet Plateau.

Key words: flower trait, reward, heritability, genetic correlation, Pedicularis semitorta Pedicularis kansuensis