More Like this

1. Spatial variation in bidirectional pollinator-mediated interactions between two co-flowering species in serpentine plant communities

   https://doi.org/10.1093/aobpla/plab069  

   Stanley, Amber; Martel, Carlos; Arceo-Gómez, Gerardo (December 2021, AoB PLANTS)

   Boege, Karina (Ed.)

   Abstract Pollinator-mediated competition and facilitation are two important mechanisms mediating co-flowering community assembly. Experimental studies, however, have mostly focused on evaluating outcomes for a single interacting partner at a single location. Studies that evaluate spatial variation in the bidirectional effects between co-flowering species are necessary if we aim to advance our understanding of the processes that mediate species coexistence in diverse co-flowering communities. Here, we examine geographic variation (i.e. at landscape level) in bidirectional pollinator-mediated effects between co-flowering Mimulus guttatus and Delphinium uliginosum. We evaluated effects on pollen transfer dynamics (conspecific and heterospecific pollen deposition) and plant reproductive success. We found evidence of asymmetrical effects (one species is disrupted and the other one is facilitated) but the effects were highly dependent on geographical location. Furthermore, effects on pollen transfer dynamics did not always translate to effects on overall plant reproductive success (i.e. pollen tube growth) highlighting the importance of evaluating effects at multiple stages of the pollination process. Overall, our results provide evidence of a spatial mosaic of pollinator-mediated interactions between co-flowering species and suggest that community assembly processes could result from competition and facilitation acting simultaneously. Our study highlights the importance of experimental studies that evaluate the prevalence of competitive and facilitative interactions in the field, and that expand across a wide geographical context, in order to more fully understand the mechanisms that shape plant communities in nature. 

   more » « less
2. Impacts of plant invasions in native plant–pollinator networks

   https://doi.org/10.1111/nph.17339  

   Parra‐Tabla, Víctor; Arceo‐Gómez, Gerardo (June 2021, New Phytologist)

   Summary The disruption of mutualisms by invasive species has consequences for biodiversity loss and ecosystem function. Although invasive plant effects on the pollination of individual native species has been the subject of much study, their impacts on entire plant–pollinator communities are less understood. Community‐level studies on plant invasion have mainly focused on two fronts: understanding the mechanisms that mediate their integration; and their effects on plant–pollinator network structure. Here we briefly review current knowledge and propose a more unified framework for evaluating invasive species integration and their effects on plant–pollinator communities. We further outline gaps in our understanding and propose ways to advance knowledge in this field. Specifically, modeling approaches have so far yielded important predictions regarding the outcome and drivers of invasive species effects on plant communities. However, experimental studies that test these predictions in the field are lacking. We further emphasize the need to understand the link between invasive plant effects on pollination network structure and their consequences for native plant population dynamics (population growth). Integrating demographic studies with those on pollination networks is thus key in order to achieve a more predictive understanding of pollinator‐mediated effects of invasive species on the persistence of native plant biodiversity. 

   more » « less
3. Community context mediates effects of pollinator loss on seed production

   https://doi.org/10.1002/ecs2.4569  

   Arrowsmith, K. C.; Reynolds, Victoria A.; Briggs, Heather M.; Brosi, Berry J. (June 2023, Ecosphere)

   Abstract A critical goal for ecologists is understanding how ongoing local and global species losses will affect ecosystem functions and services. Diversity–functioning relationships, which are well‐characterized in primary producer communities, are much less consistently predictable for ecosystem functions involving two or more trophic levels, particularly in situations where multiple species in one trophic level impact functional outcomes at another trophic level. This is particularly relevant to pollination functioning, given ongoing pollinator declines and the value of understanding pollination functioning for single plant species like crops or threatened plants. We used spatially replicated, controlled single‐pollinator‐species removal experiments to assess how changes in bumble bee species richness impacted the production of fertilized seeds in a perennial herb—Delphinium barbeyi—in the Rocky Mountains of Colorado, USA. To improve predictability, we also assessed how traits and abundances in the plant and bumble bee communities were related toD. barbeyireproductive success. We hypothesized that trait‐matching between pollinator proboscis length andD. barbeyi's nectar spurs would produce a greater number of fertilized seeds, while morphological similarity within the floral community would dilute pollination services. We found that the effects of pollinator removal differed depending on the behavioral patterns of pollinators and compositional features of the plant and pollinator communities. While pollinator floral fidelity generally increasedD. barbeyiseed production, that positive effect was primarily evident when more than half of theBombuscommunity was experimentally removed. Similarly, communities comprising primarily long‐tongued bees were most beneficial toD. barbeyiseed production in tandem with a strong removal. Finally, we observed contrasting effects of morphological similarity in the plant community, with evidence of both competition and facilitation among plants. These results offer an example of the complex dynamics underlying ecosystem function in multitrophic systems and demonstrate that community context can impact diversity–functioning relationships between trophic levels. 

   more » « less
4. From individuals to networks: The role of variation in plant–pollinator communities' responses to global change

   https://doi.org/10.1111/1365-2656.70300  

   Crall, James DeWitt; Gaiarsa, Marilia Palumbo (June 2026, Journal of Animal Ecology)

   Abstract Plant–pollinator communities are critical for biodiversity, ecosystem function and human well‐being. Yet our ability to predict divergent species responses to environmental change, the risk of abrupt collapse, or the potential for recovery in plant–pollinator systems remains limited.Here, we argue that individual variation within species may play a critical but underappreciated role in shaping the sensitivity, robustness and resilience of animal pollinators and plant–pollinator communities.We explore processes by which individual variation may influence responses to perturbation, highlighting parallels with existing niche theory at the species level (e.g. the biodiversity–ecosystem function literature). We suggest that individual variation—as a key but distinct component of total intraspecific variation—may generate more gradual (rather than abrupt) responses to environmental stress than predictions based on species means in many cases, but that these effects will depend on how traits underlying performance, interaction frequency, stress sensitivity and pollination efficacy covary among individuals.Finally, we highlight critical knowledge gaps and open questions in the structure and dynamics of plant–pollinator interactions at the individual scale and conclude by outlining a roadmap for integrating individual variation into studies of plant–pollinator communities under global change. 

   more » « less
5. Floral density and co‐occurring congeners alter patterns of selection in annual plant communities

   https://doi.org/10.1111/evo.13960  

   Eisen, Katherine E.; Wruck, Amy C.; Geber, Monica A. (April 2020, Evolution)

   Although the evolution and diversification of flowers is often attributed to pollinator-mediated selection, interactions between co-occurring plant species can alter patterns of selection mediated by pollinators and other agents. The extent to which both floral density and congeneric species richness affect patterns of net and pollinator-mediated selection on multiple co-occurring species in a community is unknown and is likely to depend on whether co-occurring plants experience competition or facilitation for reproduction. We conducted an observational study of selection on four species of Clarkia (Onagraceae) and tested for pollinator-mediated selection on two Clarkia species in communities differing in congeneric species richness and local floral density. When selection varied with community context, selection was generally stronger in communities with fewer species, where local conspecific floral density was higher, and where local heterospecific floral density was lower. These patterns suggest that intraspecific competition at high densities and interspecific competition at low densities may affect the evolution of floral traits. However, selection on floral traits was not pollinator mediated in Clarkia cylindrica or Clarkia xantiana, despite variation in pollinator visitation and the extent of pollen limitation across communities for C. cylindrica. As such, interactions between co-occurring species may alter patterns of selection mediated by abiotic agents of selection. 

   more » « less