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Abstract Detail

Pollination Biology

Paudel, Babu [1].

Interspecific variation in reproductive strategy of co-existing Himalayan gingers (Roscoea tumjensis Cowley and R.purpurea Sm.) in Nepal Himalayas- generalized versus specialized pollination system.

Background:Pollination syndrome hypothesis has been a fundamental verdict in plant reproductive biology to predict potential pollinators. Floral traits of Roscoea reflect that long tongued insects could be the most effective pollinators of this genus. However, previous studies in Chinese clades of Roscoea did not find any effective pollinators with long tongue that matches with the corolla tube length of Roscoea. This study aims to test this prediction by exploring the reproductive biology of two Himalayan clades of alpine gingers in Nepal Himalayas. Method:We studied floral biology of Roscoea tumjensis and R.purpurea in two populations for two consecutive years. Five types of pollination experiments were performed to determine the breeding system. Pollinators’ behaviour and effectiveness were assessed by observing their visitation frequency and pollination efficiency. To examine how variation of pollinators between two species is associated with floral traits, pollinators’ tongue length compatibility was compared with corolla tube length and level of nectar. Results:Peak blooming period of two species differed with little overlapping in flowering period. Both species are self-compatible, lack autonomous selfing and endure pollinator dependent breeding system. R. tumjensis exhibits generalized pollination system and is pollinated by bumblebees and moth while R. purpurea reproduces by specialized pollination system and employs Philoliche longirostris as an obligate pollinator. Reproductive success in both species of Roscoea is affected by pollen limitation. Among all pollinators, P. longirostris had highest pollination efficiency while moth had extremely low pollination efficiency. Nectar level and corolla tube length between two species differed significantly (t test, P<0.005).Nectar in R. tumjensis was accessible to all four types of pollinators while tongue length of P. longirostris was only compatible to obtain nectar from R. purpurea. Conclusions:Two species of coexisting Himalayan Roscoea exhibit contrasting breeding system and lack autonomous selfing. R. purpurea is pollinated by a specialized pollinator, P.longirostris while generalized pollinators such as bumblebees and moth are involved as effective pollinators of R. tumjensis. Temporal isolation in peak blooming period and variation in nectar level induced pollinators partitioning between two species of alpine gingers. This result contributes to explain how mismatch between flowering time and pollinator emerging time induced for the variation of reproductive strategy in closely related plant species. The findings of effective pollinators in Nepal Himalayas, which were ever unknown in Hengduan Mountain, indicates that topographic movement associated with the uplift of the Himalayas may have affected the diversification of those pollinators of Roscoea towards the Chinese Himalayas.

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1 - Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Key laboratory of Tropical forest ecology, Menglun town, Yunnan, China

Long tongued insects
Pollination syndrome
Himalayan gingers
corolla tube length
pollination efficiency

Presentation Type: Oral Paper:Papers for Topics
Session: 13
Location: Salon 6/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 3:00 PM
Number: 13007
Abstract ID:124
Candidate for Awards:None

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