The effects of community structure on ecosystem functioning often appear idiosyncratic. Differences in immigration history can be an overlooked source of this variation, as indicated by our laboratory (Fukami et al. 2010) and field (Dickie et al. 2012) experiments with wood-decaying fungi. In these experiments, we showed that small differences in early immigration history led to large differences in fungal species richness and composition, which in turn caused large differences in decomposition and carbon release from wood. We also found that the magnitude of this historical contingency was determined by top-down (nutrient concentration) and bottom-up (fungal grazing) forces (Leopold et al. 2017).
More recently, our primary study system for exploring this topic has been communities of nectar-inhabiting bacteria and fungi (Álvarez-Pérez et al. 2019), used as a natural microcosm (Chappell and Fukami 2018). Nectar microbes undergo primary succession in flowers as they colonize initially sterile nectar via pollinators (Belisle et al. 2012). We have found that immigration history has a large effect on microbial species composition via changes in nectar chemistry (Peay et al. 2012). These chemical changes affect the functioning of flowers, such as pollinator attraction and seed production (Vannette et al. 2013), and changes in pollinator visits can in turn alter microbial immigration history (Vannette and Fukami 2017) across floral generations (Toju et al. 2018). To understand this structure–function feedback more fully, we are now investigating the genetic basis of priority effects (Dhami et al. 2016) across landscapes (Dhami et al. 2018). We are also studying how historical contingency in the nectar system may be modified by climate change through phenological shifts. For more info, check out the world of nectar microbes.