Tue, Aug 16, 2022: 2:00 PM-2:15 PM
513E
Background/Question/Methods
High mountains in the tropics are characterized by biologically-rich communities that change drastically along elevational gradients. Diversity studies show two general patterns, negative linear relationships between diversity and elevation, or humpbacked patterns, where diversity peaks at mid-elevations. We evaluated variation in plant and pollinator diversity and interaction networks along elevational gradients in the high mountains of Central Mexico. We predicted that due to the harsh environmental conditions of the high mountain peaks, pollintion networks would be smaller and more specialized in high than low elevation communities, and that interactions would be influenced by plant diversity and flowering phenology. We also predicted that plants would be less dependent on pollinators at the highest elevations. To test these predictions, we surveyed plants and pollinators across in three high mountains of Central Mexico during the wet and dry seasons between 2020 and early 2022; we recorded plant, insect, and hummingbird species abundance, richness, and phenology, and documented plant-pollinator interactions in transects established in four ecosystems between 2400 and 4100 m.a.s.l. In a subset of species, we evaluated pollinator dependence and plant breeding system traits that might be critical for maintaining interactions and ensuring plant reproductive success.
Results/Conclusions
Results indicate that, for plants and insects, both species richness and abundance decreased with elevation, but for hummingbirds, the mid-elevation fir forest is the most species-rich. Overall, pollination networks had higher specialization and connectance at the highest elevations, but lower nestedness at intermediate and low sites. In one volcano, plant-hummingbird networks were larger and more nested during the dry season (November-March), while they were smaller and more specialized in the rainy season, reflecting the presence of migratory hummingbirds in the western mountains during winter months. For insects, interactions networks were larger and more nested during the rainy season at all elevations, which largely reflects the seasonality of high elevation insect communities. Preliminarily, the variation we have found in plant breeding systems shows an apparent increase in the potential for self-pollination in plant species at the highest elevation. We also documented an outcrossing species of Castilleja that has migrated to higher elevations along with its hummingbird pollinators. The results of this study show great complexity in plant-pollinator interactions in tropical high mountains, with variation in space and time, and across taxonomic groups. We make an urgent call for studies of tropical plant-pollinator interactions in high elevation habitats threatened by climate change.
High mountains in the tropics are characterized by biologically-rich communities that change drastically along elevational gradients. Diversity studies show two general patterns, negative linear relationships between diversity and elevation, or humpbacked patterns, where diversity peaks at mid-elevations. We evaluated variation in plant and pollinator diversity and interaction networks along elevational gradients in the high mountains of Central Mexico. We predicted that due to the harsh environmental conditions of the high mountain peaks, pollintion networks would be smaller and more specialized in high than low elevation communities, and that interactions would be influenced by plant diversity and flowering phenology. We also predicted that plants would be less dependent on pollinators at the highest elevations. To test these predictions, we surveyed plants and pollinators across in three high mountains of Central Mexico during the wet and dry seasons between 2020 and early 2022; we recorded plant, insect, and hummingbird species abundance, richness, and phenology, and documented plant-pollinator interactions in transects established in four ecosystems between 2400 and 4100 m.a.s.l. In a subset of species, we evaluated pollinator dependence and plant breeding system traits that might be critical for maintaining interactions and ensuring plant reproductive success.
Results/Conclusions
Results indicate that, for plants and insects, both species richness and abundance decreased with elevation, but for hummingbirds, the mid-elevation fir forest is the most species-rich. Overall, pollination networks had higher specialization and connectance at the highest elevations, but lower nestedness at intermediate and low sites. In one volcano, plant-hummingbird networks were larger and more nested during the dry season (November-March), while they were smaller and more specialized in the rainy season, reflecting the presence of migratory hummingbirds in the western mountains during winter months. For insects, interactions networks were larger and more nested during the rainy season at all elevations, which largely reflects the seasonality of high elevation insect communities. Preliminarily, the variation we have found in plant breeding systems shows an apparent increase in the potential for self-pollination in plant species at the highest elevation. We also documented an outcrossing species of Castilleja that has migrated to higher elevations along with its hummingbird pollinators. The results of this study show great complexity in plant-pollinator interactions in tropical high mountains, with variation in space and time, and across taxonomic groups. We make an urgent call for studies of tropical plant-pollinator interactions in high elevation habitats threatened by climate change.