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Abstract Detail

Pollination Biology

Lau, Jenny Yuen Yung [1], Pang, Chun Chiu [1], Saunders, Richard M.K. [1].

Evolution of pollinator traps in Goniothalamus and Dasymaschalon (Annonaceae), associated with short anthesis periods.

Annonaceae flowers are protogynous and generally have a loosely enclosed pollination chamber that is often associated with beetle pollination. Unlike most species in the family, which have anthesis over two to three days, field studies of the genera Goniothalamus, Dasymaschalon and Desmos reveal a shorter anthesis of only 23–26 hours. This compressed anthesis is hypothesized to increase the turnover rate of flowers, and hence increase potential fruit set. Mechanisms that ‘trap’ pollinators within the flower appear to have evolved independently in Goniothalamus and Dasymaschalon. Beetles that enter the pollination chamber during the pistillate phase are unable to leave the flowers until the end of staminate phase since the outer petals block the apertures located between contiguous inner petals; the release of the beetles at the end of the staminate phase coincides with the onset of the pistillate phase in other flowers and hence pollinators can move directly from staminate-phase to pistillate-phase flowers, thereby possibly increasing pollination efficiency. Desmos, which is phylogenetically close to Dasymaschalon and also has short anthesis, does not show an equivalent trapping mechanism, however.
We believe that the evolution of pollinator trapping in flowers with compressed anthesis can allow a broader range of potential pollinators, including ‘unimodal’ beetles that are primarily active in the morning as well as ‘bimodal’ beetles that are active in the morning and evening. We are investigating the daily activity pattern of the pollinators using Drosophila Activity Monitors (TriKinetics) under ambient temperature and natural photoperiod. Four beetle species in the families Curculionidae and Nitidulidae were identified as probable pollinators of Goniothalamus tapisoides. These beetle species have both unimodal and bimodal activity patterns: the morning opening of the pollination chamber in Goniothalamus tapisoides encourages the entry of the beetles that are active in the morning, whilst the evening closure of the chambers prolongs their visit, preventing the beetles that are active in the evening from leaving until the pollen is shed and pistillate-phase flowers are available in the population. Pollinator activity pattern of Dasymaschalon species, which also has floral trapping mechanism, will be studied. Desmos chinensis, which does not have a trapping mechanism, is effectively pollinated by a unimodal nitidulid beetle species that is active in the morning.

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1 - University Of Hong Kong, Pokfulam Road, Hong Kong, N/A, Hong Kong SAR

none specified

Presentation Type: Oral Paper:Papers for Topics
Session: 13
Location: Salon 6/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 2:30 PM
Number: 13005
Abstract ID:169
Candidate for Awards:None

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