The composition of species found in an ecological community is often influenced by the history of species colonization, or the order and timing in which different species joined over time. The funded project investigated the causes and consequences of such historical contingency, using a uniquely tractable study system: the communities of nectar-inhabiting fungi and bacteria that develop in the flowers of hummingbird-pollinated shrubs in California. These microorganisms immigrate to flowers via hummingbirds and other pollinators and, upon arrival, use nectar as the resource for reproduction. The researchers conducted field and laboratory experiments to test four hypotheses about historical contingency: (1) species immigration history is more variable under higher flower density; (2) more variable immigration history results in more variable species composition, affecting species diversity at multiple spatial scales; (3) species-specific traits concerning resource consumption and toxin reduction explain immigration-history effects; and (4) historically induced changes in microbial species composition alters the function of flowers for plant reproduction by altering chemical properties of nectar and, consequently, pollinator visits to flowers. Findings supported these hypotheses, although more work is needed to definitively test hypothesis 1. New knowledge gained through this project advances basic understanding of how ecological communities develop and function. It also informs agriculture as the results suggest that it may be possible to increase crop pollination by manipulating nectar microbial communities

This project integrated research and education in two ways that make them mutually beneficial. First, with nectar microorganisms used as a case study, a new inquiry-based undergraduate course was taught. In this course, students identified and worked on unanswered research questions, to learn the scientific process by practicing it. An adaptive strategy was taken, with an annual cycle of course implementation, course evaluation by science education experts, and incorporation of the evaluators' recommendations the following year. The course was adaptive in one more sense: each year new research findings was used as prior knowledge that students could build their hypotheses on. Second, the nectar microbial system was used for targeted and broad outreach activities. Targeted activities involved mentoring high-school students from under-represented groups through summer internships. Broad activities involved running workshops to share experience with teachers from community colleges and high schools and publishing peer-reviewed papers to disseminate the knowledge on science education gained through the undergraduate course and the high-school internship.

Last Modified: 03/16/2018
Modified by: Tadashi Fukami