Pronounced temporal variability of plant-pollinator networks in response to changing precipitation in the southern Chihuahuan Desert

Abstract Plant-pollinator interactions are essential for maintaining biodiversity and ecosystem functioning. Analyzing these interactions through ecological networks enables the assessment of the structure, resilience, and temporal dynamics of these mutualistic systems. However, research on the temporal variation of pollination networks is scarce for arid and semi-arid environments, where biological communities are highly dynamic due to climate variability. Here, we characterized the temporal variation of plant-pollinator networks in a semi-arid scrubland of the southern Chihuahuan Desert across two years with contrasting precipitation. We conducted monthly surveys of pollination interactions and reconstructed temporally discrete networks for three seasons of each year. We evaluated intra- and inter-annual changes in network microstructure, the identity of core species, macrostructural properties, and network robustness. Microstructural variability was modulated by precipitation dynamics, more pronounced among seasons of the same year than between years, and mainly driven by turnover of the plant species in bloom. Greater rainfall was linked to higher plant and pollinator richness, with a particular increase in the frequency and diversity of herbs, dipterans, and lepidopterans. We recorded substantial temporal variation of core species identity, yet highlight drought-resistant taxa that acted as core nodes in both years. Seasonal networks showed a persistent compound topology, where nestedness occurs within modules rather than at the whole-network scale. Specialization and modularity tended to increase under drought conditions, accompanied by a decrease in network robustness. Our results underscore the remarkable diversity and plasticity of plant-pollinator networks in semi-arid environments and provide valuable insights for their conservation under climate change scenarios.