Habitat fragmentation, global pollinator declines, and land use change are rapidly transforming ecological conditions in plant populations. What is the fate of plant populations in this increasingly altered world? Interactions between plants and their pollinators are being disrupted in human-disturbed habitats, leading to increased rates of self-fertilization (seeds produced with pollen from the same flower vs. from another plant) by plants. Because offspring produced by self-fertilization are more likely to have decreased survival and reproduction, a major conservation concern relates to whether and how loss of pollinator services for individual plants scales up to influence plant population growth and persistence. This research will experimentally evaluate the impact of changes in the frequency of self-fertilization on population growth under different ecological conditions. The focal species is affected by habitat fragmentation and is classified as imperiled in several states. Findings will contribute broadly to our understanding of and ability to predict the fates of these and other similar plant and animal species in a changing world. Additionally, the researcher will implement outreach programs, leading educational programs in plant-pollinator interactions at yearly K-6 summer camps. Yearly survey data of wild populations will be collected by citizen scientists. A postdoctoral associate, graduate student, and numerous undergraduates will be trained in research and outreach skills.
This project employs a powerful experimental demographic approach to evaluate the impact of mating system (pattern of inbreeding) on population growth of a self-compatible plant, Sabatia angularis (rosepin), across competitive contexts. Selfing rate (0%, 25%, 50%, 75%, 100%) and competitive context (high vs. low interspecific competition) of experimental populations will be directly manipulated through hand pollinations and contrasting mowing regimes. The demographic fates of all individuals will be followed over three generations. Demographic data will be used to parameterize models from which population dynamics can be derived. The impact of selfing rate, competitive context, and their interaction on vital rates (growth, survival, fecundity) and population growth rate will be evaluated, including non-linear relationships. The underlying causes of observed changes (or similarities) in growth rate across experimental treatments will be investigated with additional demographic analyses. Demographic models will also be constructed to mimic the experimental mating-system gradient by incorporating prior static inbreeding depression estimates in silico and outcomes compared to experimental results. Research findings will further address the ecological impacts of genetic load, demographic costs of selection, and impacts of intraspecific variation on species coexistence.
