Reconstructing Great Basin Butterfly-Pollen Interaction Networks over the Past Century

Aims: Insects and the plants they interact with dominate terrestrial biomes and constitute over half of the earth9s macro-organismal diversity. Their abundance in museum collections can provide a wealth of natural history data if they are collected as part of careful ecological studies or conservation programs. Here, we summarize pollen-insect quantitative networks gleaned from adult lepidopteran museum specimens to characterize these interactions and to examine how richness and frequency of butterfly-pollen associations have changed over a 100-year time series in Nevada and California. Pollen collected from well-curated butterfly specimens can provide insight into spatial and temporal variation in pollen-butterfly interactions and provide a complement to other approaches to studying pollination, such as pollinator observation networks. Location: Great Basin and Sierra Nevada: California, Nevada. Time period: The last 100 years. Major Taxon studied: Butterflies. Methods: We estimated butterfly-pollen network parameters based on pollen collected from butterfly specimens from the Great Basin and Sierra Nevada. Additionally, we pooled interaction networks associated with specimens captured before and after 2000 to compare pollen-pollinator interaction variation under drought periods in California and Nevada in the last two decades versus previous years in the time series. Results: Butterfly-pollen networks indicated that most pollen-butterfly species interactions are specialized and appear to be different from observational networks. Interaction networks associated with specimens captured before and after 2000 revealed that compared to previous decades, butterfly-pollen networks over the past 20 years had higher nestedness and connectance, with high pollen richness and low pollen abundance. Main conclusions: These findings represent another unique approach to understanding more about pollination biology, and how butterfly-pollen interactions are impacted by climate variation and ecosystem alteration.