Flower-mediated plant-butterfly interactions in an heterogeneous tropical coastal ecosystem

Island Based Assemblage Pattern and Foraging Profile of Insect Flower Visitors on Aegialitis rotundifolia -a Near Threatened Mangrove Plant from Indian Sundarban

Understanding the association pattern and foraging behaviour of flower visitors is crucial to determine their role in the interaction with plants. To analyse the insect flower visitor association as well as their foraging profile on Aegialitis rotundifolia Roxb.-a near threatened mangrove plant, present study has been conducted among four islands of Indian Sundarban for three consecutive years. Results using first three Hill numbers depicted that, the species richness and Shannon and Simpson diversity of flower visitors were higher among the islands situated far from the sea than the islands neighbouring to the sea. NMDS analysis showed moderately ordinate data structure for island-year-based flower visitor association. Furthermore, network analysis for island-based visitor assemblage showed a significantly generalised network with no specialisation among islands. Five abundant visitors were further analysed for foraging profile, where the highest foraging rate was shown by Apis dorsata Fabricius, 1793 and the highest handling time was shown by Micraspis discolor (Fabricius, 1798). Moreover, all the visitors except M. discolor showed a significant variation in their foraging rate among different time frames. Furthermore, only M. discolor showed significant variation in their foraging behaviour when compared individually with each visitor in all the time frames. Present findings conclude that, flower visitors showed a generalised assemblage pattern among islands. Both honey bees provided excellent foraging on this plant and butterflies were good foragers too. Therefore, to device conservation strategies for this plant, protection of flower visitors must be of paramount concern.

Elevational and seasonal patterns of butterflies and hawkmoths in plant-pollinator networks in tropical rainforests of Mount Cameroon

Butterflies and moths are conspicuous flower visitors but their role in plant-pollinator interactions has rarely been quantified, especially in tropical rainforests. Moreover, we have virtually no knowledge of environmental factors affecting the role of lepidopterans in pollination networks. We videorecorded flower-visiting butterflies and hawkmoths on 212 plant species (> 26,000 recorded hrs) along the complete elevational gradient of rainforests on Mount Cameroon in dry and wet seasons. Altogether, we recorded 734 flower visits by 80 butterfly and 27 hawkmoth species, representing only ~ 4% of all flower visits. Although lepidopterans visited flowers of only a third of the plant species, they appeared to be key visitors for several plants. Lepidopterans visited flowers most frequently at mid-elevations and dry season, mirroring their local elevational patterns of diversity. Characteristics of interaction networks showed no apparent elevational or seasonal patterns, probably because of the high specialisation of all networks. Significant non-linear changes of proboscis and forewing lengths were found along elevation. A positive relationship between the lengths of proboscis of hesperiid butterflies and tube of visited flowers was detected. Differences in floral preferences were found between sphingids and butterflies, revealing the importance of nectar production, floral size and shape for sphingids, and floral colour for butterflies. The revealed trait-matching and floral preferences confirmed their potential to drive floral evolution in tropical ecosystems.

Bee-Plant Interaction Networks in a Seasonal Dry Tropical Forest of the Colombian Caribbean

Mutualistic interactions between bees and flowering plants have been widely recognized as one of the most important for the maintenance of these communities throughout ecosystems. Consequently, understanding how these interactions occur is highly important, especially in seasonal dry tropical forest (SDTF), one of the most endangered ecosystems in northern South America. In this study, we analyzed the changes between interaction networks across two well-defined seasons, dry and wet, in a SDTF of the Colombian Caribbean in Taganga, Magdalena. We also determined changes in species composition and their role in interaction networks. To study this system, we compared two approaches: (1) networks constructed with data from direct collections in flowering plants, and (2) networks constructed with pollen data obtained from bees' bodies. A total of 44 species were collected in 18 species of flowering plants; also, we registered 16 additional plants presented in the records only as pollen types. We found that network metrics, connectance, nestedness, specialization (H2'), and interaction strength asymmetry remain stable through seasons. However, when the two types of approximations were compared, there were significant differences. Networks constructed with pollen data are more connected, less specialized, and with lower values of interaction strength asymmetry. The major difference between seasons relied on the interacting species composition, due to a high species turnover. Bee community was more diverse in dry season. Apidae family, mainly eusocial species, persisted in the community, being more abundant and relevant in wet season. For dry season, Megachile and other solitary species from Apidae and Halictidae families were better represented and relevant for the community. We found that Fabaceae is an important resource for bees in both seasons. In addition, herbaceous species from Asteraceae and Convolvulaceae were preferred in wet season, while shrub and tree species from Fabaceae and Polygonaceae were the main resource in dry season.

Pollination Mechanisms are Driving Orchid Distribution in Space

Understanding the abundance and distribution patterns of species at large spatial scales is one of the goals of biogeography and macroecology, as it helps researchers and authorities in designing conservation measures for endangered species. Orchids, one of the most endangered groups of plants, have a complicated system of pollination mechanisms. Their survival strongly depends on pollination success, which then determines their presence and distribution in space. Here we concentrate on how pollination mechanisms (presence/absence of nectar) are associated with orchid species density and mean niche breadth along an altitudinal gradient in six different phytogeographical regions in the Czech Republic. We found differences between these regions in terms of orchid species numbers and density. The trend (hump-shaped curve) in species density of nectarless and nectariferous orchids were very similar in all phytogeographical regions, peaking between 300-900 m. The trend strongly depends on habitat cover and pollinator availability. In general, the most specialist species of orchids were found from low to middle altitudes. The association of altitude with the richness of orchid flora is much stronger than that with the biogeography. Climate change is a factor that should not be neglected, as it may affect the presence/absence of many species in the future.