The Difference is Day and Night: Comparing Diurnal and Nocturnal Pollination Networks in a Subalpine Meadow

Paul, Janelle

Undergraduate Honors Thesis

The Difference is Day and Night: Comparing Diurnal and Nocturnal Pollination Networks in a Subalpine Meadow Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/mg74qn771

Abstract

Pollination networks are crucial for maintaining biodiversity and ecosystem stability. However, these networks are currently threatened by the rapid decline of pollinators. Our understanding of networks is limited because most of our current knowledge comes from diurnal interactions, leaving the role of nocturnal interactions understudied. In this study, I collected data on diurnal and nocturnal plant-pollinator visitation networks, as well as on a nocturnal pollen transport network in a subalpine meadow in the Rocky Mountains of Colorado, USA, in 2023. To record interactions, I conducted diurnal and nocturnal sampling by observing flowers. I additionally used UV traps to collect nocturnal Lepidoptera and swabbed them for pollen which I later identified. Specifically, I asked: (1) how do network size and pollinator composition differ between the diurnal and nocturnal visitation networks? And (2) how do the diurnal and nocturnal visitation networks and the nocturnal pollen transport network differ in structure? Network size substantially differed between diurnal and nocturnal visitation networks, with 122 diurnal and 39 nocturnal unique interactions observed. The composition of insects significantly differed between the nocturnal and diurnal visitation networks. While diurnal and nocturnal flower visitors had representatives from Diptera, Hymenoptera, Coleoptera, Hemiptera, and Lepidoptera, there were notable differences in abundance and species composition. Nocturnal networks had lower visitor species richness, specialization, connectance, and nestedness than diurnal networks. I concluded that nocturnal interactions represent important components of plant-pollinator networks and should not be neglected. Understanding pollinator species differences aids ecosystem understanding and species coexistence, benefiting ecological theory and management in changing climates. These findings highlight dynamic plant-pollinator interactions, promoting integrated approaches.

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