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Plant species with the trait of continuous flowering do not hold core roles in a Neotropical lowland plant-pollinating insect network

Citation

Hinton, Chelsea; Peters, Valerie (2021), Plant species with the trait of continuous flowering do not hold core roles in a Neotropical lowland plant-pollinating insect network , Dryad, Dataset, https://doi.org/10.5061/dryad.sqv9s4n32

Abstract

Plant-animal interaction science repeatedly finds that plant species differ by orders of magnitude in the number of interactions they support. The identification of plant species that play key structural roles in plant-animal networks is a global conservation priority, however, in hyperdiverse systems such as tropical forests, empirical datasets are scarce. Plant species with longer reproductive seasons are posited to support more interactions compared to plant species with shorter reproductive seasons but this hypothesis has not been evaluated for plant species with the longest reproductive season possible at the individual plant level, the continuous flowering phenology. Resource predictability is also associated with promoting specialization, and therefore continuous flowering may instead favor specialist interactions. Here we use quantitative pollinating insect-plant networks constructed from countryside habitat of the Tropical Wet forest Life Zone and modularity analysis to test if species that share the trait of continuous flowering hold core roles in mutualistic networks. With a few exceptions, most plant species sampled within our network were assigned to the role of peripheral. All but one network had significantly high modularity scores and each continuous flowering plant species was in a different module. Our work reveals that the continuous flowering plant species differed in some networks in their topological role, and that more evidence was found for the phenology to support specialized subsets of interactions. Our findings suggest that the conservation of Neotropical pollinating insect communities may require planting species from each module rather than identifying and conserving network hubs.

Methods

This study took place in the southern Pacific lowlands of the Puntarenas Province of Costa Rica in the Osa Peninsula. We selected 8 sampling locations where we identified plant species that exhibit a continuous flowering phenology. A total of six plant species with this phenology were found through the study area. Since we were particularly interested in evaluating species topological roles and were including plant species with extended phenologies, we aimed to increase our resolution of within season interactions by (1) observing each plant individual for a 30-minute observation period, (2) conducting repeated sampling at all sampling locations within a season and (3) sampling across eight sampling locations throughout the Osa Peninsula that had similar plant species compositions, habitat types, and surrounding land use types (see Study Sites and Pollinator Sampling section from Hinton and Peters 2021). We focused on collecting bees (Hymenoptera: Apoidae) and butterflies (Lepidoptera), since they were the primary flower visitors. Collected Lepidoptera were taken to the UGA field station in NW Costa Rica and were identified to species or genus by J. Montero and using the guides (DeVries 1987, Glassberg 2018). Bees were preserved in 70% ethanol and were exported to Eastern Kentucky University where they were identified to species, genus or morphospecies using several keys: Michener (2000), Mawdsley (2017), Aguiar and Melo (2011), and Roubik and Hanson (2004). Centridini and Ceratinini bee species were identified using reference collections established by J. Pawelek and Dr. S. Rehan, respectively.