Pollinator-mediated natural selection inPenstemon digitalis

Abstract

Measuring the agents of natural selection is important because it allows us to understand not only which traits are expected to evolve but also why they will evolve. Natural selection by pollinators on floral traits is often assumed because in outcrossing animal-pollinated plants flowers are generally thought to function as advertisements of rewards directed at pollinators. We tested the role of bee pollinators in selection on Penstemon digitalis and found that pollinators were driving selection for larger and more flowers. However, what makes our publication unique is the additional information we gained from reviewing the few other studies that also directly tested whether pollinators were agents of selection on floral traits. As we would expect if pollinators are important agents of selection, selection on floral traits was significantly stronger when pollinators were present than when their choices were experimentally removed. Taken together, these results suggest that pollinators can be important drivers of selection in contemporary populations. Plants and PollinatorsIn a recent publication, 1,2 we show that pollinators can drive selection on floral traits of Penstemon digitalis. Moreover, we found that although there are few studies available that directly test whether pollinators are the agents of natural selection, selection on floral traits is generally stronger in the presence of pollinators than in their absence.1 These results are important because they both empirically demonstrate that pollinators can and do act as agents of selection in the wild and that pollinator-mediated selection in

Herbivores and plant defences affect selection on plant reproductive traits more strongly than pollinators

“…For example, plant–pollinator interactions are viewed as the primary driver of the evolutionary diversification of floral traits in angiosperms (Fenster, Armbruster, Wilson, Dudash, & Thomson, ; Kay & Sargent, ). Pollinators exert direct selection on numerous reproductive traits that increase pollination success, including flower number (Conner, Rush, Kercher, & Jennetten, ; Parachnowitsch & Kessler, ), size (Benitez‐vieyra, Medina, Glinos, & Cocucci, ) and colour (Hopkins & Rausher, ; Irwin & Strauss, ; Sletvold, Trunschke, Smit, Verbeek, & Ågren, ), flowering phenology (Sandring & Ågren, ), and mating system (Bradshaw & Schemske, ; Gervasi & Schiestl, ). In addition to pollinators, it is increasingly recognized that reproductive traits are subject to selection by antagonistic herbivores and that selection is altered by variation in plant defensive chemistry, although the relative effects of these three agents have yet to be investigated.…”

Insect trash is a plant’s treasure: effects of insect exuviae as soil amendment on pollinator performance and plant reproduction

“…farming practices) and natural (e.g. pollinators) environments and are known to impact plant fitness (Strauss and Whittall, 2006;Parachnowitsch and Kessler, 2010;Rusman et al, 2019a). For instance, changes in the soil associated with the use of fertilisers can impact the plant and plant-associated community (Ramos et al, 2018;Carvalheiro et al, 2021).…”