Spatiotemporal shifts in the role of floral traits in shaping tropical plant-pollinator interactions

Abstract

The pollination syndrome hypothesis predicts that plants pollinated by the same pollinator group bear convergent combinations of specific floral traits. Nevertheless, some studies have shown relatively low predictive power for these floral trait combinations. This discrepancy may be caused by changes in the importance of specific floral traits for shaping interactions under different environmental conditions and for different pollinator groups. To test this, we studied pollination systems and floral traits along an elevational gradient on Mount Cameroon during wet and dry seasons. Using Random Forest models, allowing the ranking of traits by significance, we demonstrated that some floral traits are more important than others in shaping interactions and that these traits predict pollinators relatively well. However, the distribution and importance of traits varies under different environmental conditions. Our results imply the need to improve our trait-based understanding of plant-pollinator interactions to better inform the debate surrounding pollination syndrome hypothesis.

Role and patterns of butterflies and hawkmoths in plant-pollinator networks at different elevations and seasons in tropical rainforests of Mount Cameroon

“…Bees, flies, beetles, and other moths were more common flower visitors than butterflies (Klomberg et al, 2020). Wasps, nectarivorous birds and carpenter bees were more common visitors than sphingids, followed by cockroaches and mammals (Klomberg et al, 2020). Still, butterflies and sphingids were among the two most common flower visitors for some plant species, such as Scadoxus cinnabarinus (Amaryllidaceae), Distephanus biafrae and Melanthera scandens (both Asteraceae), and Cordia aurantiaca (Boraginaceae) for butterflies;…”

“…Our detailed taxon-specific approach uncovered some of the limitations of the pollination syndrome hypothesis, especially that different traits can differ in their importance among particular syndromes, and that even individual subgroups of the single pollinator group can differ in their preferences (cf. Dellinger, 2020;Klomberg et al, 2020). Figure S1.…”

“…We recorded flower-visiting lepidopterans at the four elevations (650, 1,150, 1,450 and 2,250 m a.s.l. ), along six transects (200×10 m) per elevation established to characterise the local vegetation heterogeneity (Klomberg et al, 2020). Along those transects, we recorded flower visitors of all plant species flowering during our fieldwork (two weeks during dry and wet seasons at each elevation; Table 1) using security cameras with IR night-vision (Vivotek IB8367RT).…”

“…The role, relative proportions in communities, and specific adaptations of pollinator groups shift under differing environmental conditions, such as temperature, solar radiation, and precipitation (e.g. Ollerton et al, 2006;Klomberg et al, 2020). Unfortunately, neither elevational nor seasonal patterns of tropical lepidopteran role in pollination networks were studied, except a few case studies of individual plant species (e.g.…”

“…Elevation and seasonality, representing various environmental and ecological gradients, influence patterns in biotic interactions (Klomberg et al, 2020;Poisot et al, 2015). The role, relative proportions in communities, and specific adaptations of pollinator groups shift under differing environmental conditions, such as temperature, solar radiation, and precipitation (e.g.…”