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Scientific Interests & Origins

"Every kid has a bug phase. I just never grew out of mine."; E. O. Wilson

I am a scientist today because I sniffed flowers and chased butterflies as a child.

I was born with an affinity for natural history that was encouraged by my family and teachers during childhood and provided an outlet for my creative energies and anxieties during adolescence. I was motivated to become a professional biologist by the desire to explore the inner workings of the natural world and to communicate my sense of joy in its discovery.

I count myself among the fortunate souls who are living the dreams they had for themselves as children. My dream had a tangible beginning, captured in this photo (above right; 1970). The dapper man holding a newly emerged Cecropia Moth is Campbell Norsgaard, a film-maker and naturalist who brought Rachel Carson's gospel to suburban New Jersey inthe 1960s and 70s. This was the moment (at age 5) when I became interested in moths, an interest that has continued unabated for 40 years. It is a personal example of how the "Broader Impacts" activities advocated by NSF really can enhance scientific awareness.

My fledgling interests in natural history were not confined to insects: I collected shells,fossils and stamps, pressed plants with my mom, learned constellations with my dad, and shot my very first roll of film on the classification of cloud types!  Our human brains have been honed by millennia of selective pressure to recognize and interpret patterns in our environment. My developing brain was very interested in the patterns that allowus to classify and understand biological diversity, and field guides (Golden, Peterson, Audobon) were my constant companions as I sought to interpret such patterns.

A chance meeting with a 94 year old German moth breeder living in the Sullivan Co. NY Catskills named Max Richter introduced me to W.J. Holland's "The Moth Book" . This delightful tome was written at the turn of the 19th century, and its pages upon pages of species descriptions and color(!) plates were punctuated by whimsical tales of the author netting hawkmoths at evening primrose flowers by lamplight in Japan and "sugaring" for underwing moths (Catocala spp.) with molasses and stale beer painted onto tree trunks. Even in the fragmented landscapes of northern NJ, I was able to follow Holland's lead and study moths in these ways, and it compelled me, for the first time, to really think about moths as more than something to collect, and to care about their life histories and habits.

When I got to Yale and began my transition from collector to scientist, I was struck by the contrast between two fields in which scientists interested in butterfly biodiversity worked. Systematics struck me as a realm for frustrated attorneys, characterized by vehement arguments, decade-long grudges and cults of personality. Chemical ecology, though it had its share of debates and personalities, seemed less dogmatic and more open to exploration and discovery, as its practitioners were still determining how to define pattern and process at the chemical level. Coevolution and mimicry were the most exciting ideas that I encountered as an undergraduate, and ecological chemistry appeared to be the key to understanding them.

Valerio Sbordoni, Saverio Forestiero, Butterflies of the World, Times Books, 1984

Although I struggled to grasp chemical theory in the large, pre-med courses I took, I really enjoyed analytical lab work, especially the use of gas chromatography (GC) to separate blends into their component peaks. During an otherwise difficult sophomore year, I realized that I would really enjoy combining GC and other forms of analytical chemistry with questions that addressed how butterflies and other insects interacted with their host plants.

It took me five additional years (and false starts in population genetics and molecular biology) to embrace this path, but I eventually realized that chemical ecology, grounded in sensory physiology and behavior, was the way I wanted to study biological diversity. That path has led me and my students to Neotropical rainforests, to the deserts and semitropical grasslands of the American southwest, Argentina and South Africa, to the boreal forests of Alaska and austral forests of Patagonia, and finally to the deciduous northeastern forests of Ithaca, where the field of chemical ecology, in many respects, was born.

Professional Background and Path

I have been fortunate to know and train with many inspiring, patient and excellent scientists. I met some of them by chance, others through the natural process of following my interests, but all of them helped me to find my own voice as a biologist and introduced me to the community of scientists to which I now belong. Here I recognize their contributionsto my education with fondness and gratitude.

My first research experience came during two summers (1982-83) as a technician in Darcy Kelley's lab at Columbia University. I was just a high school student, but Darcy introduced me to so many ideas, techniques andpeople (including John Hildebrand) that would later become a huge part of my life. She also introduced me to the concept of research centers like the Marine Biological Labs at Woods Hole, MA, where she taught each summer.

Marine Biological Labs, Woods Hole, MA July 1983

I attended Yale as an undergraduate (1983-87), due to my desire to study butterflies with Charles Remington, a co-founder of the Lepidopterists' Society and an influential figure in the development of butterflies as model systems for the study of evolution and population genetics. As my first mentor, Charles introduced me to the culinary delights of New Haven and challenged me to expand my interests beyond butterflies (to moths, aquatic insects, biogeography, chemical ecology) and subtly motivated me to travel and gain field experiences of my own by invoking the accomplishments of my predecessors at Yale, such as Lincoln Brower, Naomi Pierce, Bob Pyle and Francie Chew.

Charles Remington, in the Yale Peabody Museum, courtesy of Science magazine, April 1992

In summer 1985, I had two such opportunities. The first came at Mt. Lake Biological Station near Blacksburg,VA, where I worked with Bev Rathcke and Leslie Real. Their NSF-funded study of nectar variance in heath balds (mountain top communities of Kalmia and Vaccinium shrubs) focused on risk aversion by bee pollinators. The hard physical labor of data collection, stimulating discussions of experimental design and intense social experiences and beautiful setting of Mt. Lake were stimulating, and the weeks passed quickly. I realized how little I knew about plants during this time, and became motivated to learn more about pollination.

Beverly Rathcke, Bald Knob, Mt. Lake Biological Station, Pembroke, VA, June 1985

Carol Horvitz, Lago Catemaco, Veracruz, Mexico, July 1985

Leaving the southern Appalachians, I flew to Veracruz, Mexico to join Carol Horvitz and Doug Schemske on another NSF-funded project, this one focused on plant-pollinator-ant ecological networks in the tropical understory herb, Callathea ovandensis. Each day we drove to ourrainforest field site at Laguna Encantada, in the crater of a small volcano, and returned each evening to the delightful town of Catemaco, with its salsa music, cowboy cuisine andbrujo folklore. I was overwhelmed by tropical biodiversity and my first immersion in the Spanish language, and initiated a butterfly survey that would become my first publication.

I returned to Yale completely motivated to become a field biologist and clean up my act academically. In retrospect I am astonished to have had the chance to learn from four terrific ecologists in one summer, each inspiring in their own ways. I was also very fortunate to have worked on such conceptually ground-breaking projects. Pollinator risk-sensitivity remains an important question 25 years later, as does the use of path analysis to untangle complex plant-pollinator interactions in a whole-plant context. Although I didn't realize it then, the summer of '85 set me firmly on my current path.

My eventual honors research project, initiated with Rick Harrison and completed in Jeff Powell's lab, was a test of geographic isolation and genetic drift using allozyme and morphometric data from Colias interior populations separated by 8-12000 generations due to the retreat of the Laurentides Ice Sheet in eastern North America. I learned a lot about neutral theory and starch gel electrophoresis, but in the end I failed to reject the null hypothesis, and experienced a deep frustration with the iterative nature of population level sampling with unknown variance structure, a statistical discomfort which temporarily distanced me from science and eventually led me to change fields. But the project introduced me to one of Charles Remington's most accomplished former students, Ward Watt, whose group studied the evolutionary genetics and functional ecology of Colias butterflies at Stanford University.

Ward hired me as his lab technician for 2 stimulating years (1988-89) at Stanford, where I learned HPLC and PAGE, cared for thousands of caterpillars, attended classes and met some of my most enduring friends in biology, including Zoe Cardon, Mike Romero and Manuel Lerdau. Ward always made time to talk candidly about academic science as a career path. I doubt that I would be a professor today if not for his guidance, and my mechanistic bias reflects his commitment to integrating between different levels of analysis.

Ward Watt injecting a Colias butterfly flight muscle sample for HPLC analysis, Stanford Biology Dept. Bulletin, 1988

Leslie Gottlieb (L) and Eran Pichersky (R), April 1991, Ann Arbor MI

A seminar by his colleague Leslie Gottlieb fundamentally altered my ideas about science through his explicit use of the hypothetico-deductive method to frame his research questions and his use of fast-growing annual wildflowers (Clarkia) as a genetically tractable, ecologically interesting model system for studying plant evolution. I was determined to bring something new to the study of insect-plant coevolution, and reasoned that the next stage of my education should examine the plant point of view.

In 1989, I moved to Ann Arbor to begin my doctoral studies with Eran Pichersky at the University of Michigan. Eran was a young assistant professor who had studied gene duplication in Clarkia with Les Gottlieb at Davis, and was interested in the evolution of novel plant traits. Eran suggested that I study the de novo evolution of floral scent associated with a shift to hawkmoth pollination in Clarkia breweri for my thesis. At the time I was taking a Plant-Insect Interactions seminar with Bev Rathcke, whom I already knew from Mt. Lake, and Michael Martin, a chemical ecologist known for his work on digestive physiology in leafcutter ants and caterpillars. Bev and Mike became very important members of my doctoral committee in years to come. My assignment in their class was to critically assess the importance of fragrance in pollination, and I searched the literature exhaustively for evidence. I was shocked by how little I found: aside from the classic studies of sexually deceptive and euglossine bee-pollinated orchids, and Heidi Dobson's pioneering work on pollen volatiles, nearly nothing was known about the genetics, biochemistry, ecology or evolution of floral scent. Anything that I found would be NEW!

Now my task was to learn how to collect and analyze floral volatiles, which nobody at Michigan was doing.  With advice from Heidi, Olle Pellmyr and Mark Whitten, I slowly mastered GC and mass spectrometry (GC-MS) working midnight-to-dawn shifts on an ancient Finnigan quadrupole in the Chemistry Dept. My epiphany came when I realized that 2-methoxy-4-(2-propenyl) phenol or "eugenol" was clove oil, which made flowers of C. breweri smell "spicy" to my nose! Learning to equate mass spectra with odors that pleased or disgusted me was like learning the script of an ancient language, and it made organic chemistry fun. Armed with GC-MS and inbred plant lines, our work on the genetics and biochemistry of scent in C. breweri took off when Eran returned from a sabbatical with Rodney Croteau having cloned the first floral scent biosynthetic gene from Clarkia, linalool synthase (lis). Patterns began to emerge from our genetic and chemical data, such as a duplicate gene whose enzyme product methylates eugenol or isoeugenol in certain populations of C. breweri, which Jihong Wang would study for her thesis. This was a tremendously exciting time for all of us, and the pace of discovery doubled when Natalia Dudareva brought her skills in RNA isolation to Eran's lab. Their work has altered the landscape of plant volatile metabolism, and I feel fortunate to have explored the first blind alleys of floral scent biology with them. Although I never became a plant molecular biologist, Eran patiently trained me to be a skeptical scientist, to respect data over theory, and to organize my life and my mind.

My doctoral committee after my thesis defense, U. of Michigan, April 1995. (L to R) Beverly Rathcke, George Brewer, Eran Pichersky and Michael Martin

Clarkia concinna (top), Clarkia breweri (lower left) and F1 hybrid (lower right)

With guidance from Bev Rathcke and colleagues in Davis, such as Maureen Stanton and Robin Thorp, I studied the pollination biology of Clarkia breweri in coastal California and found that the large, scented flowers of C. breweri indeed had shifted to hawkmoth pollination, but also attracted hummingbirds as another novel (albeit inefficient) pollinator class! I did not immediately grasp the implications of this result for the "specialized vs. generalized pollination" debate, but it did reinforce the caveat that pollinator shifts don't occur in a community vacuum.

Female Black-chinned hummingbird visiting a flower of Clarkia breweri, Del Puerto Canyon, CA, May 1993

Douglas Light at his EAG rig, USDA-ARS Albany CA, May 1994

As my thesis drew to a close in 1995, I read Tinbergen's "Curious Naturalists" and thought about the many ways that moths might respond to odors. During a visit to the USDA-ARS labs in Albany, CA, Doug Light taught me how to measure the antennal responses of hawkmoths to floral odors, and I enjoyed it immensely. This seemed like an exciting direction for postdoctoral research, and a way to shift my focus back to the Lepidoptera with a new set of tools.

Doug suggested that I visit the University of Arizona, where John Hildebrand headed a division of neuroscientists who used a hawkmoth, Manduca sexta, as a model system for studying sensory organization. I had met John 13 years earlier at Woods Hole, and knew him to be a gregarious and energetic champion of insect olfactory neurophysiology. His interest in expanding models of olfaction to include plant volatiles as well as sex pheromones made me feel welcome in his group, through which I met so many of the sensory biologists whom I now count among my closest colleagues.

Sunset at the Arizona-Sonora Desert Museum, Tucson AZ, Aug. 1996

My postdoctoral work in Tucson was funded through the Center for Insect Science, and while based in the Hildebrand lab I was associated with two additional mentors: Mark Willis, a Jedi master of wind-tunnel behavioral assays with moths, and Reg Chapman, an eminent insect sensory physiologist and the author of the classic text " The Insects; structure and function". Mark and I worked together after sunset at the Arizona-Sonora Desert Museum, one of the truly magical places in my life. So many of our experiments were hatched during these evenings, while we filmed wild hawkmoths visiting Datura flowers in the pollinator gardens and were struck by their obvious integration of olfactory and visual floral stimuli. Tutorials with Reg convinced me that their feeding behavior had to be multimodal. John Alcock's evocative use of hypothesis trees in his "Animal Behavior" textbook inspired the design of our ethological experiments, in which Mark and I demonstrated synergism between floral odors and visual display in nectar feeding by Manduca sexta, by experimentally decoupling and recombining these stimuli. These were technologically simple, yet tremendously satisfying ethological experiments, which generated many new questions about the sensory world of Manduca sexta, some of which continue to be studied by members of John Hildebrand's group as well as my own students.

Like many in my cohort, I did not want to leave Tucson, where beautiful landscapes, a thriving artistic community, authentic Mexican cuisine and a critical mass of insect scientists made my postdoctoral years delightful. Beyond the Division of Neurobiology, I enjoyed interactions with Steve Buchmann, Liz Bernays, Dan Papaj and especially Judie Bronstein and Goggy Davidowitz, with whom I currently collaborate. During this time (1996-99) Tucson was ground-zero for the phylogenetic revolution, and I gravitated to Lucinda McDade, whose keen insights, generous mentorship and wicked humor attracted a crowd of students and postdocs with phylogenetic interests to her lab and the UA herbarium. Lucinda, her student Rachel Levin, and I puzzled over how correlated biochemical characters such as floral volatiles could best be mapped onto phylogenetic relationships. This question fueled my second postdoc, funded through an NSF training grant in Biodiversification to the Dept. of Ecology and Evolution, and later generated my first NSF grant (written with Lucinda) and much of Rachel's doctoral thesis, focusing on three plant lineages in which hawkmoth pollination has been repeatedly gained and lost. This project provided the transition to my first job, at the University of South Carolina, and strengthened ties with botanists studying the Onagraceae (Warren Wagner, Peter Hoch, Liz Zimmer, Ken Sytsma), Nicotiana (Tim Holtsford), and hawkmoth pollination (Andrea Cocucci, Steve Johnson).

Lucinda McDade, Rancho Santa Ana Botanic Garden, Claremont CA, May 2009

Nicotiana section Alatae from subtropical South America. Clockwise from left: N. alata, N. plumbaginifolia, N. longiflora, N. forgetiana, N. bonariensis, N. langsdorffii

I'll conclude with a vivid memory of a turning point in my professional life. In 1998 I was struggling to land a job, running out of funding, and felt that I had fallen into the cracks between several fields. Gunnar Bergstrom was visiting Tucson and I joined him, John Hildebrand and John Law, the CIS director, for a terrific Mexican dinner at Cafe Poca Cosa. At one point I asked Gunnar why there had never been a meeting or symposium focused on floral scent, to which he responded that he and his colleagues had always studied floral volatiles (especially in Ophrys) as a way to learn more about bees, rather than to understand flowers per se. John Law, who was a board member of the Gordon Research Organization, suggested that Gunnar and I apply to establish a new Gordon Research Conference on Floral Volatiles, which we did! In fact, John Hildebrand established a new GRC for Neuroethology during the same year, which we celebrated in back-to-back meetings at Queens' College, Oxford, UK in September 1999. One of the most thrilling moments of my life was walking onstage to welcome the attendees of our first conference, including many of the people whose papers I had read over the years, but I had never met. Gunner, Heidi Dobson, Jette Knudsen and I spent a year inviting these speakers, raising funds and welding together a program that would create a new field. The cultural clashes, instant collaborations and intellectual energy resulting from that conference were unforgettable, and set the course for the next stage of my life, as a young professor of chemical ecology. Here's to you, John Law!

Attendees of the first Gordon Research Conference on Floral Volatiles, Queen's College, Oxford, UK, Sept. 1999.