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Abstract Detail

Botany 2015 Colloquium: Integrated perspectives on the ecology, genetics and coevolution of intimate mutualisms

Svensson, Glenn P. [1], Okamoto, Tomoko [2].

The role of floral scent in Epicephala moth nursery pollination system.

The nursery pollination association between seed parasites of the moth genus Epicephala (Gracillariidae) and their host plants of genera Breynia, Phyllanthus, and Glochidion (Phyllanthaceae) has emerged as a new model system for understanding the evolution and diversification of obligate mutualisms. Epicephala pollination takes place at night when host flowers are fragrant, and we have via laboratory bioassays shown that female moths (i) prefer host scent over non-host scent, (ii) are attracted to both male and female floral scent of their host, and (iii) prefer the scent of male flowers over that of female flowers, suggesting that male floral scent elicits pollen-collecting behaviour in the pollinator. Molecular phylogenetic data reveal that specialisation to Epicephala evolved at least five times within monoecious Phyllantheae, which offer multiple independent comparisons of male and female floral scent in taxa with and without Epicephala dependence. We have shown that for all three lineages analysed, colonisation by the moths resulted in strong sexual dimorphism in floral scent, strongly indicating that pollinator-mediated selection is the main mechanism for the evolution of floral scent in this system. Epicephala-pollinated plants also have more fused female flowers than related non-moth pollinated plants and such limited style spreading makes pollen accessible only to Epicephala females with a modified proboscis, again indicating that specialisation to obligate pollinators drives evolution of female floral traits in Phyllantheae. Finally, it is suggested that the evolutionary stability of mutualisms is enhanced when interacting species possess mechanisms to prevent overexploitation by one another. One such mechanism could be a change in the scent profile for already pollinated flowers to reduce subsequent pollination/oviposition attempts by the seed parasite. Via hand-pollination experiments, in combination with electrophysiological and chemical analyses, we have found evidence for adaptive post-pollination change in scent production by female host flowers, i.e. only antennal-active compounds showed reduced release rates after pollination, which may be a way for the plant to avoid overexploitation of the seed bank.

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1 - Lund University, Department of Biology, Solvegatan 37, SE-22362, Lund, Sweden
2 - Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, 305-8687, Ibaraki, Japan

Floral scent
Odour-guided behaviour
Post-pollination mechanism.

Presentation Type: Colloquium Presentations
Session: C4
Location: Hall C/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 4:15 PM
Number: C4011
Abstract ID:153
Candidate for Awards:None

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