Plant Ecology and Evolution 149(3): 319-328, doi: 10.5091/plecevo.2016.1258
Floral scent and flower visitors of three green-flowered Costa Rican and Panamanian Blakea species (Melastomataceae) indicate birds rather than rodents as pollinators
expand article infoPetra Wester, Marc Filla, Klaus Lunau
‡ Institute of Sensory Ecology, Heinrich-Heine-University, Universitätsstr. 1, D-40225 Düsseldorf, Germany
Open Access
Background and aimsBlakea austin-smithii, B. chlorantha and B. aff. penduliflora from Costa Rican cloud forests share floral traits with rodent-pollinated plants, e.g. cryptic, inconspicuous, green flowers, and are known to be visited and probably pollinated by rodents. However, contrasting records indicate birds as pollen vectors for B. chlorantha. Previously, three Costa Rican Blakea species were described to have flowers lacking scent discernible to humans which is typical for bird-pollinated but not for rodent-pollinated flowers. This study aims at evaluating the role of rodents and birds as pollinators of B. austin-smithii and B. chlorantha in Costa Rica as well as the yet unstudied B. gregii in Panama. Therefore, additional diurnal observation data as well as data on floral traits were collected.
Methods – In addition to floral visitor observations during the day and measurements of nectar properties, floral colour and morphology, floral scent was analysed by means of coupled gas chromatography - mass spectrometry. Two bee-pollinated Blakea species were chosen as methodological standards.
Key results – We observed three passerine bird species, Chlorospingus flavopectus, C. pileatus, Myioborus torquatus, and the hummingbird Lampornis calolaemus visiting B. austin-smithii as well as the hummingbird Panterpe insignis visiting the similar Panamanian B. gregii. Whereas no scent was detected in B. austin-smithii, B. chlorantha and B. gregii, strong odours of B. maurofernandeziana (rose-like) and B. anomala (lemon-like) could be confirmed with the finding of > 70% phenylethyl alcohol, and monoterpenes, respectively.
Conclusions – The bird observations together with lacking olfactory signals point to birds as main pollinators. However, to clearly evaluate pollinator importance of the different vertebrates, further observations and proof of pollen transfer are needed.