Browsing by Author "Esposito, Fabiana"
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- Foraging Behavior and Pollen Transport by Flower Visitors of the Madeira Island Endemic Echium candicansPublication . Esposito, Fabiana; Costa, Ricardo; Boieiro, MárioThe study of flower visitor behavior and pollen transport dynamics within and between plants can be of great importance, especially for threatened or rare plant species. In this work, we aim to assess the flower visitor assemblage of the Madeiran endemic Echium candicans and evaluate the performance of the most common visitors through the analysis of their foraging behavior and pollen loads. The flower visitor assemblage of E. candicans is diverse, including several insect groups and the endemic lizard Teira dugesii, but bees are the most common visitors. In general, large bees (Amegilla quadrifasciata, Apis mellifera, and Bombus spp.) had the highest average visitation rates (>18 flowers/min) and their pollen loads had higher percentages of homospecific pollen (>66%) when compared with butterflies and hoverflies. The honeybee (Apis mellifera) and two bumblebees (Bombus terrestris and B. ruderatus) were the most efficient flower visitors of E. candicans, but their foraging behavior seems to favor geitonogamy. Other visitors, such as butterflies and the small bee Lasioglossum wollastoni, may have a complementary role to the honeybee and bumblebee species, as their high mobility is associated with fewer flower visits on each plant and may promote xenogamy. Two non-native bees (A. mellifera and B. ruderatus) are important flower visitors of E. candicans and may contribute mostly to self-pollination rendering the endemic plant more vulnerable to inbreeding effects.
- Pollen morphology of the endemic genera of the Madeira archipelago, PortugalPublication . Esposito, Fabiana; Morgado, L.N.; Nunes, Telmo; Rego, Carla José Azevedo; Fernandes, Francisco; Boieiro, MárioABSTRACT: This study presents the first palynological characterisation of the five endemic plant genera of the Madeira archipelago: Chamaemeles Lindl, Melanoselinum Hoffm., Monizia Lowe, Musschia Dumort and Sinapidendron Lowe. Pollen grain morphology of ten endemic species was studied using light and scanning electron microscopy techniques. The size and shape of pollen grains, the polar axis, the equatorial diameter, and the exine ornamentation were measured and described. We found that the pollen grains of the five endemic genera are all medium-size monads. The close relative apiaceous Melanoselinum and Monizia differ in polar (P) and equatorial (E) diameter size and exine ornamentation while Sinapidendron species show differences in P, E, and P/E ratios. The pollen grains of the two Musschia species are very similar to each other, but differ in morphology and ornamentation from the Macaronesian endemic bellflowers Azorina vidalii and Canarina canariensis. This study unveiled differences between the endemic taxa and with their close related species, thus providing support to previous taxonomic findings.