Yuhina nigrimenta Blyth (Zosteropidae) as a bird pollinator of Brandisia hancei Hook.f. (Scrophulariaceae) during winter


Abstract: Winter-flowering plants commonly attract an insufficient number of pollinators. Harsh climate conditions, such as low temperature, make it impossible for insects to evolve as reliable pollinators. Birds can buffer against changes in weather to be more reliable pollinators for these kinds of plants, such as Brandisia hancei Hook.f. (Scrophulariaceae), a shrub endemic to the Northeast Sichuan Basin in China. In this study, the flower visitors, flowering phenology, pollinators, breeding system, and nectar availability of B. hancei Hook.f. were investigated. Results show that the flowering period duration was approximately 3 months for the whole population and more than 10 days per flower. B. hancei Hook.f. is known to be self-compatible but may need pollinators. According to our findings, the passerine bird Yuhina nigrimenta Blyth was the only visitor and pollinator attracted by the copious dilute nectar. The birds carried large pollen loads and exhibited high pollen deposition. The seed set from hand-selfing pollination (87.68 ± 0.89%) was similar to that of cross-pollination (87.25 ± 1.17%), with values significantly higher than those of the control (65.63 ± 4.15%). In addition, the fruit and seed sets of bagged flowers were considerably low, which suggested that B. hancei Hook.f. depends on flower visitors for pollination. Therefore, we conclude that flower longevity might be increased by attracting this pollinator. B. hancei Hook.f. can also reproduce via cross- and self-pollination. All these mechanisms may be regarded as an adaptation to adverse weather conditions.

Keywords: Brandisia hancei Hook.f., Scrophulariaceae, Yuhina nigrimenta Blyth, winter flower, floral syndrome

Full Text: PDF