GLENCOE, Ill. (October 7, 2013) – Chicago Botanic Garden researchers have received a $1.54 million Dimensions in Biodiversity grant from the National Science Foundation to study the way flowers use scent to attract the pollinators they need to reproduce and survive. The floral scent may also draw flower predators, and this can play an important role in the evolution and diversification of plant species. The Dimensions of Biodiversity program is a “race against time” to transform our understanding of the scope and role of life on earth, according to the NSF. The program promotes novel, integrated approaches to studying the evolutionary and ecological significance of biodiversity.
“What we’re trying to do is understand the role floral scent has had in creating the diversity of both the plants and insects we see today,” said Garden conservation scientist Krissa Skogen, Ph.D., principal investigator for the five-year project. “Why are there so many species? Why are they different? How is that diversity maintained? Developing a better understanding of the dynamics among plants, mutualists, and enemies is essential for documenting and conserving biodiversity and may impact specific conservation actions in the face of changing threats.”
(Dr. Skogen describes the evolution of her research project in a recent blog posting.)
Dr. Skogen is heading a multidisciplinary team of collaborators focusing on four main players: flowers, pollinators, predators and scent. The flowers belong to the evening primrose family. Its more than 650 species make it one of the most diverse plant families growing throughout the western United States. Their pollinators are hawkmoths and bees native to the arid lands. Acting as foe are micromoths, called Mompha moths, the only known group of lepidopterans (butterflies and moths) to prey specifically on evening primroses. Both friend and foe are attracted to the plant by the heavy scent produced by the flower. Skogen suspects that scent directs the interplay of flower, friend and foe, and may be a key driver of evolutionary changes in all three.
(A recently released Plants Are Cool, Tool! video follows Dr. Skogen into the field.)
“This project is a terrific example of the work that we do at the Chicago Botanic Garden,” said Greg Mueller, Ph.D., Negaunee Foundation vice president of science at the Garden. “It combines cutting- edge science with an in-depth understanding of field botany to answer important plant evolution questions while providing information to better conserve plants and animals in their native habitats.”
The study will focus on the species in the Oenograe tribe of the evening primrose, or Onagraceae, family. This group of plants provides an ideal subject because floral scent varies within and among species and also populations of species. One important scent compound, known as linalool, is simple enough to manipulate experimentally, which Skogen and her colleagues plan to do. This group of plants is primarily pollinated by hawkmoths (Hyles, Manduca and other species), large, striking Lepidoptera that typically feed from dusk to dawn.
(Garden President Sophia Siskel caught up with Dr. Skogen in New Mexico this past summer. Her blog captures conservation science in the field and describes the larger role the Garden plays in restoring and protecting the habitats on which all life depends.)
Oenothera produce “classic” hawkmoth flowers that are yellow or white, open at night, are highly fragrant, and hold lots of nectar, the reward the moths are seeking, according to Skogen. The flowers have evolved to deposit pollen on the moth’s tongues and bodies, so it is carried from flower to flower. Pollination enables the plants to reproduce sexually and promotes genetic diversity among plant populations. The hawkmoths are unwitting participants in the process. “They’re looking for nectar,” Skogen said. “They probably do not know or care if they have pollen on them, which works out well for the plants.” Among other things, the collaborators will help identify the scent components that attract particular moths though electroantennography “interviews,” Skogen said. “We won’t know what the insects can smell until we ‘ask’ them.”
The strong floral fragrance of these species may also attract a lesser-known group of Mompha moths, micromoths roughly 1 centimeter long who use evening primrose to rear their young. Micromoth larvae bore into the stem, flower and fruit of these plants. The micromoth almost certainly exerts selective pressure on the evening primrose species as its caterpillars eat flowers, fruits and seeds, all of which are required to produce the next generation of plants. What remains unknown is how important these tiny moths are in driving the evolution of flower features and, therefore, species. What is also unknown is how changes in scent alter the species preferences of the Mompha moth.
“Projects like this add to our collective knowledge of native pollinators. What resources and habitats do they require? How do they interact with flowers? Why do they choose some over others? This grant will move forward our understanding of how plants and insects interact and how these interactions may explain why we see the great diversity of flowering plants and insects we see today,” said Skogen, who holds a doctoral degree in ecology and evolutionary biology from the University of Connecticut. “We’re highly likely to uncover new species of micromoths, as well.”
The grant, titled “Landscapes of Linalool: Scent-Mediated Diversification of Flowers and Moths across Western North America,” will enable Skogen and other Garden scientists to team with other plant scientists, plus moth and floral chemistry experts, at Cornell University, Amherst College, Colorado College, Oberlin College, the University of Illinois at Champagne-Urbana, Agriculture & Agri-Food Canada - Eastern Cereal and Oilseed Research Centre, the University of California at Santa Cruz and the Smithsonian Institution.
“It’s a team effort in the true sense of the word,” Skogen said. “There’s no way I could ever do this by myself.” The team includes Garden conservation scientists Jeremie Fant, Ph.D., and Norm Wickett, Ph.D., and will soon be joined by two new post-doctoral researchers. The post-docs will be charged with leading efforts to sample 80 populations of Oenothera across western states over the first two years of the grant. They will collaborate with local colleges and high schools, providing many students in isolated areas the rare opportunity to collaborate with professional scientists. The study will engage more than 200 students from the high-school through post-doctoral level. These are the professional collaborators:
- Krissa Skogen and Jeremie Fant (Chicago Botanic Garden) have conducted detailed studies of O. harringtonii over five years, including population biology, pollination and reproductive biology, population genetics, and plant and insect community dynamics.
- Norm Wickett (Chicago Botanic Garden) has worked extensively with genomic data and its assembly and annotation, is currently a principal investigator on the NSF-funded Assembling the Pleurocarp Tree of Life project, and is currently analyzing large, nuclear gene phylogenetic data sets as part of the 1KP Project.
- Robert Raguso (Cornell University) has characterized the floral scent and pollination biology of several species of Oenothera and has extensive field experience with section Pachylophus (O. cespitosa).
- Rachel Levin (Amherst College) has contributed heavily to recent taxonomic revision of Onagraceae and specific lineages of Oenothera.
- Terry Harrison (University of Illinois at Urbana-Champaign) and Jean-Francois Landry (Agriculture &Agri-Food Canada, Eastern Cereal and Oilseed Research Centre) provide specific expertise in morphological and molecular systematics of Mompha, microlepidopterans.
- Sylvia Kelso (Colorado College) lends expertise in community impacts on floral ecology, through biotic (functional group analysis) and abiotic (edaphic specialization) factors.
- Kathleen Kay’s (University of California, Santa Cruz) research combines pollinator specialization, reproductive isolation and rates of diversification in flowering plants.
- Mike Moore (Oberlin College) studies gypsum endemism in the Chihuahua Desert, plant systematics and provides expertise in key sections with in Oenothera.
- Warren Wagner (Smithsonian Institution) has extensive experience in the evening primrose family, including systematics, biogeography and floristics.
For more information about the NSF Dimensions in Biodiversity program click here.