Format: ORAL

Shayla Salzman1

1 University of Georgia, Athens, USA

Cycads are an ancient lineage of dioecious gymnosperm that overwhelmingly rely on insect mutualists for pollination services, providing an excellent opportunity for studies into the ecology and evolution of insect pollination, plant-insect signaling, and the maintenance of mutualisms. Specialized cycad-beetle pollination has existed since at least the early Jurassic, placing it before the ecological dominance of angiosperms and the accompanying diversification of major lineages of pollinators such as butterflies and bees (Cai et al 2018). Entire lineages of beetles exclusively live on and pollinate cycads in what has been suggested to be a classic case of co-evolution. Chemical communication (scent) has been shown to be important for the maintenance of these mutualisms (Salzman et al. 2021) and for plant reproduction through push-pull pollination (Terry et al. 2007), the most ancient pollination mechanism yet documented (Salzman et al 2020), yet scent is not the only signal influencing pollinator behavior (Salzman et al. 2023). These entomophilous plants produce dense woody reproductive cones without the overt visual signals commonly employed by angiosperms and must rely on other signals and cues for communication with their insect partners. As such, they are thermogenic plants, producing internal heat within their reproductive structures that in turn alters the carbon dioxide, humidity, and scent of the cones. All of the plant produced primary and secondary metabolites that are perceived by pollinators are used in decision making. I will discuss plant signaling and morphology in an ecological and evolutionary framework to understand extant and ancient pollination. Cai et al. 2018. Current Biology 28: 2806-2813. Salzman et al. 2020. Science Advances 6: eaay6169. Salzman et al. 2021. Frontiers in Plant Science 12: 639368. Salzman et al. 2023. Current Biology 33: 1654-1664. Terry et al. 2007. Science 318: 70.