Pollination Biology Of 5 Species Of Parnassia L. In Yulong Snow Mountain

The genus Parnassia with cascaded movement of stamen and the highly diversified staminodes is a model system to address the evolutionary and ecological questions of floral adaptation. In this study, we focus on five sympatric distributed Parnassia species( Parnassia wightiana, P. delavayi, P. tenella, P. mysorensis and P.yunnanensis) in Yulong Snow Mountain, southwestern Yunan. We comparatively investigated their floral biology, phenology, floral foragers, floral herbivory, the function of staminodes and germination of seeds by combing field observation and lab experiments. Specifically, we studied the breeding system and stamen movement of P. wightiana in detail. Our previous observation suggested that the flower of P. wightiana was heavily herbivored by beetle Nonarthra sp. and most beetle were feed on the staminodes. Therefore, we hypothesized that there is a trade-off between floral(staminde) herbivory and pollinator attraction, their balance may drive the phenotypic evolution of P. wighitana.The results shown that 1) The staminodes, especially the sparkle tips of staminodes were highly attracted to floral foragers; Pollinator approached staminodes first, and collect nectar at the base of staminode, and foraged one-by-one of stamninodes by a way of circle, these visiting pattern promoted the floral reproductive organ to contact the body of insects; Herbivory beetle Nonarthra sp. fed on staminodes, by this way, it left ovaries intack, which suggested that staminodes also have indirect defense mechanism to protect female organ. 2) All five species shown stamen cascaded movement, three species P. wightiana,P. delavayi and P. mysorensis had similar movement pattern, one stamen of these species lasted one-two days. P. tenella had lowest movement rate, it produced one stamen by more than two days interval. When removed the non-mature stamen, the anther dehisced stamen will increase its during of anther dehisce. The cascade movement of stamen increased the male reproductive fitness. 3) We found that staminodes are a buffer of ovaries for defense of beetle herbivory, early flowering individuals had higher fruit production and seed set compared with late flowering individuals, early flowering may be a mechanism to response of mal-adaptive of beetle activity.In general, we provide the evidence of that floral traits were selected by multiple factors, herbivory could be a driven force for phenotypic variation. This study highlight a holistic approach combined effects of pollinators, herbivore and other environmental factors to study flower trait in the future.