Monica Geber


My research falls into three areas at the interface of ecology and evolutionary biology. First, my main focus is on the genetic and ecological limits to adaptive evolution, especially in relation to species’ range limits. Second, I am interested in the direct and indirect links between species diversity and community change, on the one hand, and genetic diversity and evolution within species, on the other. Finally, I have had a long-standing interest in interactions between plants and their pollinators and the consequences of these interactions for plant mating system evolution and plant community structure.





Aubrie James

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I am a sixth year PhD student, and my favorite way to look at the natural world is through the lens of community ecology. I study in the Clarkia plant system with Monica and Kate, and we often collaborate with our pals in the Moeller and the Eckhart labs. My current focus is on how four sympatric species of Clarkia native to the Sierra Nevada foothills (C. xantiana, C. cylindrica, C. speciosa, and C. unguiculata)  interact remotely via their shared, specialist bee pollinators. My loose master plan in my time at Cornell is to empirically nail down mechanisms of direct and indirect plant interactions in the Clarkia system, and then use mathematical tools to understand the interaction-space where stable coexistence (as in neo-chessonian theory) of these four species is the outcome.

My current project (summer 2016) involves testing the community-level effect of different Clarkia communities on pollinator attraction and behaviour. This year, I experimentally varied Clarkia community densities (low number of plants to high number of plants per unit area) and Clarkia community richness (one species stands versus multiple species stands) in a gridded array. For each density-by-richness treatment, I kept track of which pollinators showed up and how they moved in the array. I encourage you, dear reader, to ask me about it, especially if you like to talk excitedly about flowers, bees, and/or rolling around in the dirt. More about me here:





Kate Eisen 

DSCF2450 copyI am a fifth year PhD student and I spend a lot of time thinking about how plant species interact in communities where they co-occur. To me, flowers are the most exciting and incredible parts of these plants because their often flashy traits like color, spotting, and scent, have evolved to attract pollinators who facilitate reproduction. While plant-pollinator dynamics are typically studied as pairwise interactions between one plant species and one pollinator species, these interactions take place in often complex ecological communities. I am curious about how co-occurring plant species can impact pollinator-mediated selection on floral traits, potentially generating character displacement in sympatry.

My current research explores this question in communities of Clarkia (Onagraceae) in the southern Sierra Nevada. While four species of Clarkia (C. cylindrica, C. speciosa, C. unguiculata, and C. x. xantiana) are sympatric in the region and share specialist solitary bee pollinators, they also differ in some traits (flowering time, floral shape) that may reduce competition for pollination in these communities. In my first year, I worked with Rob Raguso to characterize floral scent in the southern Sierra Clarkias in a common garden greenhouse experiment. During my first field season (Summer 2015), I measured selection on floral traits in communities with 1-4 species of Clarkia to determine if community context alters patterns of selection in natural communities. I hope you’ll contact me if you’d like to hear more about my research or talk about cool flowers, measuring selection, or how to prevent herbivores from eating my field experiments. For more about my past and current research, please visit my website:





Gregor Siegmund 

I am in the fifth year of Cornell’s PhD program in the Geber lab. I spent much of my first year considering how community ecology, coexistence theory and rapid evolution might intersect. Ecological communities are constantly being reshuffled: species are removed as they go extinct, novel species added through the introduction of novel community members or speciation, and species are moved around as their ranges shift. I’m interested in the causes and consequences of this reshuffling on contemporary timescales. Specifically, can evolution driven by species interactions affect how ecological communities are assembled? To address this question experimentally, I’m starting work with annual plants in the Great Basin that grow with sagebrush as well as with a novel community member, cheatgrass (Bromus tectorum). Other interests, still to be integrated into a cohesive whole, include demographic modeling and species distributions.

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