Affiliation:
1. Department of Entomology, Plant Sciences Building 4112, 4291 Fieldhouse Drive, University of Maryland , College Park, MD 20742 , USA
Abstract
Abstract
Background and Aims
Floral characteristics vary significantly among plant species, and multiple underlying factors govern this diversity. Although it is widely known that spatial variation in pollinator groups can exert selection on floral traits, the relative contribution of pollinators and climate to the variation of floral traits across large geographical areas remains a little-studied area. Besides furthering our conceptual understanding of these processes, gaining insight into the topic is also of conservation relevance: understanding how climate might drive variation in floral traits can serve to protect plant–pollinator interactions in globally change conditions.
Methods
We used Rhododendron as a model system and collected floral traits (corolla length, nectar volume and concentrations), floral visitors and climatic data on 21 Rhododendron species across two continents (North America, Appalachians and Asia, Himalaya). Based on this, we quantified the influence of climate and pollinators on floral traits using phylogeny-informed analyses.
Key Results
Our results indicate that there is substantial variation in pollinators and morphological traits across Rhododendron species and continents. We came across four pollinator groups: birds, bees, butterflies and flies. Asian species were commonly visited by birds, bees and flies, whereas bees and butterflies were the most common visitors of North American species. The visitor identity explained nectar trait variation, with flowers visited by birds presenting higher volumes of dilute nectar and those visited by insects producing concentrated nectar. Nectar concentration and corolla length exhibited a strong phylogenetic signal across the analysed set of species. We also found that nectar trait variation in the Himalayas could also be explained by climate, which presented significant interactions with pollinator identity.
Conclusions
Our results indicate that both pollinators and climate contribute and interact to drive nectar trait variation, suggesting that both can affect pollination interactions and floral (and plant) evolution individually and in interaction with each other.
Funder
United States–India Educational Foundation Fulbright-Nehru Postdoctoral Fellowship
Azalea Society of America, the Maryland Native Plant Society
American Rhododendron Society
Department of Biotechnology, Government of India
Publisher
Oxford University Press (OUP)
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