Biodiversity-ecosystem function relationships in natural systems
Ecosystem services (e.g. carbon storage, pollination) are derived from Earth’s biodiversity and are essential for human life. It is unclear how these services will be affected by frequent losses of species in response to human activities. Our perception of how biodiversity drives ecosystem services relies on highly-controlled experiments, and it is unclear if those results can be extended to the real world.
Resolving this knowledge gap is difficult, because real world data are messy. Abundance is highly variable, community composition changes non-randomly, and richness is confounded with both. A promising approach for dealing with real-world data is the “ecological” Price equation, which partitions any changes in ecosystem services into three different components of biodiversity: species richness; community composition; and the “context dependence effect”, which includes any factor that changes species’ abundances and/or per-capita contributions to ecosystem services. I recently published a version of the ecological Price equation for the temporal variance of ecosystem services (Ecology 2017) and was awarded an NSF grant to explore this research area with existing data. As part of the NSF grant, I published a synthetic analysis (GEB 2020) and hired a postdoc (Dr. Tina Harrison) who developed new analytical methods (AmNat 2022).
Plant-pollinator interactions and pollination efficiency
Pollination ecology has often viewed plant-pollinator interactions in terms of abundance – how many flowers, and how many pollinators. However, we would never simply count the number of trees in a forest to estimate carbon storage, so pollination ecologists need to do better in this area. So far, little work has examined whether variation in pollinator behavior (nectar vs. pollen foraging, order or plant visits, etc.) or traits (body size, tongue length, hairiness, etc.) affects the actual benefit that plants receive per pollinator visit. Using these methods we have estimated the pollen deposition rates of rare and declining bee species for a paper that is in revision at Ecology.
Effects of within-species variation in plants on associated communities
Not all individuals of a species are exactly the same; this is an obvious statement, but for many years, within-species variation was under-appreciated. Spurred on by the now-established field of community genetics, within-species genetic variation is recognized as a driver of community structure and ecosystem processes (Functional Ecology 2011). My PhD focused on indirect genetic effects (IGEs), which occur when the expression of genes in one individual affects the phenotype of an interacting individual. To my knowledge, my co-authors and I were the first to apply IGEs, which were well-established in behavioral ecology, to plant-plant interactions. We showed that IGEs between interacting plants could impact above- and below-ground biomass (Genung et al. Ecology Letters 2012, Ecology and Evolution 2013), herbivory (Oecologia 2012), pollinator visitation (Ecology Letters 2012, PLoS ONE 2010), decomposition rates, and nutrient cycling (PLoS ONE 2013). Following the publication of this research, I was invited to write an article for The Scientist describing the many ways IGEs can manifest themselves in a range of biological disciplines (The Scientist 2014).
Plant and pollinator ecology of the Cajun prairie
The gulf coastal prairie in Louisiana (known locally as the Cajun prairie) once occupied 2.5 million acres, but only a few hundred acres remain. While there has been considerable interest in the native plants of the Cajun prairie, much less is known about their pollinators. We want to understand which pollinators are key for the reproduction of prairie plants, and which plants are important for the nutritional needs of pollinators. Building this knowledge could help guide and improve ongoing restoration efforts in the prairie. This work has been funded by the Louisiana Department of Education, and a grant from the U.S. Fish and Wildlife Service will continue to fund the work starting in 2023.