CAREER: Evaluating the contribution of Sensory Drive to the divergence of flower color

Clemson University, Clemson SC

Investigators

Abstract

Plants have evolved flowers of notably different colors, often due to preferences of different pollinators. However, within some plant species there are populations that have different colored flowers although the pollinator species are the same. Floral color differences could evolve without pollinator shifts if plant populations live in different habitats that affect the way that flowers appear to pollinators. In particular, the color of the background can affect the way that pollinators see colors. Alternatively, differences in environmental factors like water availability could also affect flower color. This project assesses how flower color may evolve to be different between populations without major shifts in pollinator species. It focuses on populations of a widespread plant in different habitats that differ starkly in background color. The research will help us better understand how flowers evolve to attract pollinators. It can also help predict how floral signals may change as climate change affects the timing and location of flowering. In addition, the project provides training in research and scientific outreach for undergraduate students. In animal behavior studies, Sensory Drive describes the situation whereby communication signals change when the signaling environment changes. This project will assess the contribution of Sensory Drive to flower color evolution while also testing longer-standing theoretical drivers of floral diversity. Using a bee-pollinated annual, Phacelia dubia, that transmits floral signals to pollinators in either rocky outcrops or grassy meadows, the project will employ 1) observations and experiments in 12 natural populations to evaluate the contributions of Sensory Drive and pollinator-shifts to changes in flower color, 2) a 4-generation experimental evolution study to evaluate whether the background habitat color spurs rapid flower color evolution, and 3) growth chamber experiments and long term data collection in natural populations to assess the role of environmental variables in shaping flower color. With an integrative educational program the project will also engage undergraduates, 4-H Junior Naturalists, and Native Plant Society members to address whether background-dependent evolution contributes to color diversification across a broad range of species, and to link pollinator behavior with the results of natural selection in experimental populations. This project is jointly funded by the Division of Environmental Biology (DEB) and the Established Program to Stimulate Competitive Research (EPSCoR). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.