NSF Postdoc Fellowship in Biology FY 2017: Convergent evolution of biotic pollination in wind-pollinated angiosperm linages: functional and genomic exploration of a rare transition

Gardner Elliot, Evanston IL

Investigators

Abstract

This is an NSF Postdoctoral Research Fellowship in Biology, under the program Research Using Biological Collections. The fellow, Elliot Gardner, is conducting research and receiving training that utilizes biological collections in innovative ways, and is being mentored by two sponsoring scientists at two host institutions: Andrew Hipp at The Morton Arboretum and Robert Raguso at Cornell University. The fellow's research project uses field studies, DNA sequencing of museum collections, and chemical analysis of floral scent to investigate convergent evolution of animal pollination of plants, specifically the oak, mulberry, and palm families. Transitions from wind to animal pollination are considered rare but likely represent an important pattern of flowering plant evolution. Although not closely related, these diverse plant families have all evolved similar dense spikes of tiny flowers that use scent to attract small insect pollinators, and these insects often use the flowers as brood sites. The fellow's research challenges some assumptions about the evolution of animal pollination, providing an important foundation for future studies on pollination transitions and, more generally, convergent evolution. The project is improving our understanding of the biology of diverse tropical trees - including important but underutilized crops - and promoting international cooperation with researchers in developing countries. The fellow is contributing to public education and outreach programs, as well as research opportunities for high-school and undergraduate students. This project will produce a multidimensional picture of convergent transitions from wind to insect pollination in three divergent lineages. Data from field studies, herbarium specimens, and chemical (GC-MS) analysis of floral scent will support ancestral state reconstructions and phylogenetic comparative analyses to reveal patterns associated with transitions. Targeted sequencing of the entire terpene synthase gene family - involved in floral scent production - will reveal gene duplication and loss as well as molecular signatures of selection associated with pollination transitions. Using herbarium specimens will enable dense sampling within the target clades, highlighting the potential of museum collections for targeted next-generation sequencing. The project will generate a trait data base and genomic resources for hundreds of taxa, and clarify phylogenetic relationships in three important clades. Results will provide insight into a remarkable pattern of convergent evolution, and may shed light on the emergence of biotic pollination in ancient lineages such as cycads, whose fragrant cones resemble the convergent pattern described here. The fellow is teaching a portion of an advanced phylogenetics course, and engaging in outreach to the public and younger students through the host institution.