Fall 2011 - the Department of Biology - Syracuse University

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FACULTY PROFILE:Kari SegravesExamine any natural community and you will find a bewildering network of species interactions thatrange from non-specific, intermittent associations to ones that are profoundly specialized and lasting.As Charles Darwin emphasized in the Origin of Species, it is without question that this “entangled bank”of interactions has played a critical role in creating the diversity of species on Earth. The importance ofspecies interactions, however, extends well beyond this scientific perspective. They are part of our everydaylives—from the gut microbes that assist us with digestion to the stimulating effects of caffeine, a chemicalbyproduct of plant evolution that discourages insect herbivores. My research focuses on the interactionsbetween plants and insects, two species-rich groups that are important both in terms of biodiversity andagriculture.If someone had told me in my senior year of high schoolthat I would become a biology professor at a highly rankedresearch university, I would have said that they were crazy. Atthe time, I was exploring careers in photography or math, and itwas purely fortuitous that I decided to round out my senior yearwith a course in ecology. It wasn’t until much later in my careerthat I began to appreciate the uniqueness of this educationalexperience, especially for someone growing up in a tiny town insoutheastern Washington State. My devoted teacher took us onfield trips nearly every day the weather was decent, traveling tothe local river in a dilapidated school bus to catch insects, pressplants, and seine for fish. In addition to these short trips, wealso journeyed on weeklong adventures to Mount St. Helens andthe Oregon coast, where we identified countless organisms andobserved firsthand many of the concepts discussed in class. Itreally wasn’t until our final trip to the Oregon coast that I realizedI wanted biology to be a bigger part of my life. As I stood kneedeepin the cold Pacific waters, I knew that I wanted to learnmore about the natural world around me.I decided to attend Washington State University whereI promptly declared biology as my major, and during mysophomore year I started taking upper division biology andother science courses. That year I studied limnology, marineinvertebrate ecology, and botany. Much to my surprise, Idiscovered my favorite classes were botany and chemistry,two seemingly disparate subjects. During my junior year, afriend pointed out that the university housed a biochemistrydepartment where I could pursue both of my interests. So Idecided to double-major in biology (ecology and evolution) andbiochemistry, with the idea that the latter addition would makeme marketable, because at the time I believed that a degree inecology and evolutionary biology was unlikely to lead to a “real”job. My days were divided between donning my lab coat to studythe effects of alcohol on spermatogenesis in rats and taking field10 THE DEPARTMENT OF BIOLOGY AT SYRACUSE UNIVERSITY
trips to northcentral Idaho to survey plantand insect populations.As I learned more about eachof my projects, I found myselfgravitating toward my research on theplant Heuchera, or alum root. I wasinvestigating a moth (Greya) that bothfeeds on these plants and pollinates them,but what I found particularly intriguingwere the genetic features of the plants.Across its relatively small geographicIt really wasn’t until ourfinal trip to the Oregoncoast that I realized Iwanted biology to be abigger part of my life.As I stood knee-deep inthe cold Pacific waters,I knew that I wanted tolearn more about thenatural world aroundme.range, we found that the plants varied inchromosome number, with some havingthe typical diploid set of chromosomes(two of each chromosome) whileothers were tetraploid (four of eachchromosome). On top of this, there wasalso some evidence for hybridizationwith another Heuchera species. Theseinteresting findings led me to stay atWSU for a master’s degree, where Istudied how these genetic factors affectedthe plant’s ecological interactions withGreya moths and the other insects thatvisited the flowers. I decided to use acombination of lab and field approachesin my project, employing moderntechniques in “molecular ecology”to assess the relatedness of plantsand apply this to my field research. Iwas surprised to learn that in somepopulations the diploid and tetraploidplants differed slightly in flower shape,whereas in other populations the twochromosomal complements were difficultto distinguish. What was really excitingwas the finding that, even when therewas no apparent physical difference,both Greya and various other insectvisitors could distinguish between thetwo genetic forms. For instance, I foundthat bumblebee queens preferred tocollect nectar from tetraploids whereasthe workers of the same species foragednearly exclusively on diploid plants. Soin instances when I was challenged to tellthe two types of plants apart even with mymolecular toolkit, I found it interestingthat the flower visitors possessed anunknown mechanism to distinguishthem. Although I enjoyed working in thelab, it was the field research that solidifiedmy desire to continue on with a Ph.D.After spending several years workingon the Greya moths that pollinated andfed on Heuchera, I became interestedin how mutualistic associations evolve.Mutualisms are interactions betweenspecies where both partners benefitfrom the association. For example, thefemale moths that forage for nectar onHeuchera pollinate the plant and alsolay eggs in the flowers. Once the larvaehatch, they feed on a small fraction ofthe plant’s seeds, so both the moth andplant benefit from the interaction. Asa master’s student I began to focus onhow the balance is maintained betweenpartners in a mutualistic association, andwhy one partner doesn’t take advantage ofthe other such that it gains more from theinteraction. For instance, what preventsthe moths from laying so many eggs thatthe larvae consume all of the seeds? Inessence, why don’t moths cheat?Given my interest in the evolutionof cheating in mutualism, I decided toattend Vanderbilt University for a Ph.D.where I was advised by Olle Pellmyr,a leading researcher studying howmutualisms evolve. He focused on theinteraction between yucca plants andyucca moths (Tegeticula) as his mainstudy system. I saw many advantages toworking with Olle on Tegeticula as thesemoths were familiar because they areclose relatives to the Greya moths that Istudied on Heuchera, and the yucca-yuccamoth interaction is a textbook exampleof mutualism. Yuccas, or century plants,feature prominently in desert ecosystemsas an important resource for manyanimals. The plants and their flowersYucca aloifoliaYucca shidigeraYucca filamentosaFALL 201111
Page 2: 4DeanGeorge M. LangfordEditorErnest
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Page 23 and 24: UNDERGRADUATE STUDENT PROFILE:Emily
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Page 35 and 36: Who, What, When, WherePeter V.N. Bo
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