Graduate Students

 Michelle Afkhami (meafkhami[at] I am a 6th year Population Biology PhD student in Strauss lab at the UC Davis. I am interested in the incorporation of positive species interactions, such as mutualisms and facilitation, into conceptual ecology and evolution. For my dissertation, I am addressing the role of mutualistic interactions in niche theory (e.g. mutualist-mediated niche expansion and differentiation) via modeling, greenhouse, and field approaches with the symbiosis between a fungal  endophyte and a west coast endemic grass. Please see my website for more details on my research, CV, etc. Publications:

  • Afkhami, M.E., J.A. Rudgers, & J.J. Stachowicz. (In review) Multiple Mutualist Effects: The importance of mutualist diversity in ecology. Ecology Letters. Reviews and Synthesis section.
  • N.D. Charlton,K.D. Craven, M.E. Afkhami, G.A. Swoboda, B.A. Hall, S.R. Ghimire, & C.A. Young. (In review) Genetic diversity in epichloid endophytes of Bromus laevipes provides evidence for independent hybridization events. Molecular Ecology.
  • Afkhami, M.E. & P.J. McIntyre. (In review following revision) Beyond the fundamental niche: Niche expansion at a rangewide scale linked to a mutualist. American Naturalist.
  • Gorischek, A.M., M.E. Afkhami, E.K. Seifert, & J.A. Rudgers. (Accepted with minor revision) Fungal symbiont manipulates host plant reproduction. American Naturalist.
  • Afkhami, M. E. (2012) Fungal endophyte-grass symbioses are rare in the California floristic province and other regions with Mediterranean-influenced climates. Fungal Ecology special issue. 5(3): 345-352.
  • Afkhami, M. E. & J. A Rudgers. (2009) Endophyte-mediated resistance to herbivores depends on herbivore identity in the wild grass, Festuca subverticillata. Environmental Entomology. 38(4): 1086-1095.
  • Rudgers, J.A., M. E. Afkhami, M. A. Rúa, A. J. Davitt, S. Hammer, & V. M. Huguet. (2009) A fungus among us: broad patterns of endophyte distribution in the grasses. Ecology. 90(6): 1531-1539.
  • Afkhami, M. E. & J. A. Rudgers. (2008) Symbiosis Lost: Imperfect vertical transmission of fungal endophytes ingrasses. The American Naturalist. 172: 405-416.
  •  Afkhami, M. E. & J. E. Strassmann. (2007) Adult Yellow-crowned Night-herons face in opposite directions at the nest. The Wilson Journal of Ornithology. 119:747–749.
  • Afkhami, M.E. & S.Y. Strauss. (In prep) Linking an experimental test of drought tolerance to rangewide patterns of mutualist-mediated niche expansion and differentiation in a fungal endophyte-grass symbiosis.
  • Afkhami, M.E. & S.Y. Strauss. (In prep) Experimental test of mutualist-mediated effects on the niche in a grass-fungal endophyte symbiosis at a large spatial scale.

Kyle Christie (kchristie[at] I got hooked on botany as an undergraduate at Colorado College in 2001, and have since worked as a field botanist throughout the Southwest. I have been involved with various ecological monitoring surveys, floristic inventories, vegetation mapping projects, and rare plant surveys. My explorations on the Colorado Plateau, in the Mohave, Sonoran, and Great Basin Deserts, in the southern Rocky Mountains, and in the high Sierra Nevada have piqued my curiosities about plant evolution, phytogeography, rare plant biology/ecology, plant-substrate interactions, and edaphic specialization in plants. I completed a Master’s degree at Northern Arizona University in 2006, in which I explored floristics, local scale vegetation shifts across an edaphic gradient, and regional phtyogeographical affinities of Pinyon-Juniper woodlands on the Colorado Plateau. Now at UC Davis I hope to frame my research interests within an evolutionary context. I am interested in: 1) modes and mechanisms of edaphic specialization and/or speciation in plants, 2) geographic and geologic patterns of plant speciation and diversity, and 3) how the combination of phylogenetic and ecological factors can act to shape plant community composition and distribution. Publications:

  • K. Christie. 2012 (in revision). Floristic dynamics across a semi-arid chronosequence in Northern Arizona. Southwestern Naturalist.
  • K. Christie, G. Rink, and T. Ayers. 2011. Additions to the flora of Grand Canyon National Park resulting from National Vegetation Mapping Program fieldwork. Canotia 7: 41-53.
  • Hill, M., T. DeKoker, K. Christie, G. Rink, and T. Ayers. 2010. Herbarium reviews for eight parks in the Southern Colorado Plateau Network. Natural Resource Technical Report NPS/SCPN/NRTR – 2010/317. National Park Service, Fort Collins, Colorado.
  • K. Christie. 2009. Phytogeography and floristics of Pinyon-Juniper woodlands in northern Arizona. Western North American Naturalist 69(2): 155-164.
  • K. Christie. 2008. Vascular flora of the lower San Francisco Volcanic Field, Coconino County, Arizona. Madroño 55(1): 1-14.
  • K. Christie. 2006. Noteworthy Collections – Arizona. Madroño 53(4): 409.
  • K. Christie, M. Currie, L.S. Davis, M. Hill, S. Neal, and T. Ayers. 2006. Vascular Plants of Arizona: Rhamnaceae. Canotia 2(1): 23-46.

Anna O’Brien I am a PhD student in the Population Biology Graduate Group and am coadvised by Jeff Ross-Ibarra ( I am broadly interested in how biotic interactions change over environmental gradients and influence plant range limits. Currently, I am studying how interactions between teosinte (Zea mays ssp. parviglumis & ssp. mexicana) and its associated microbial community change over the range of teosinte. Specifically, I hope to evaluate the microbial community across the range for both community species makeup and functional nature (i.e. mostly mutualistic or mostly pathogenic), and to look for evidence of adaptation to local communities in teosinte using genetic data. Moria Robinson I grew up on Vashon Island, Washington, and attended college in Middlebury, Vermont. My research interests center upon herbivorous insects and the relationships they maintain with both their plant resources and predators. More specifically, I am fascinated by the immature stages of Lepidopterans (butterflies and moths), the diverse chemistry of their host plants, and the unique hymenopteran (~wasp) and dipteran (~fly) parasitoids that constitute a primary top-down control upon their populations. Specialized interactions abound in these tri-trophic systems, presenting a framework to explore questions of plant and insect evolution and diversification. Although I have yet to narrow the path of my doctoral research, I hope to incorporate the following questions: (1) What determines host plant choice by insects, and what is the degree of rigidity/plasticity of these relationships? What are the relative roles of plant chemistry, caterpillar metabolic ability, and predation, as well as heterogeneity of environmental factors such as resource availability and climate?  (2) How do disturbances cascade through trophic levels?  Precipitation, drought, and fire events affect soil and plant chemistry in a variety of ways. How might these fluxes cascade through caterpillar diet choice to the wasp and fly predators that find and attack them? (3) How does the ecology of a lineage vary across space, and what can this tell us about mode of evolution? Single taxa of butterflies and moths may be involved in a mosaic of distinct interactions with predators and resources across their range, which may contribute to evolutionary divergence. For example, the spring azure butterfly Celastrina ladon uses unique host plants and exhibits varying phenotypes across its North American range. In the Eastern US, C. ladon has been re-classified as a complex different species; what could spatial variation in ecological interactions tell us about its parallel species complex in the West? In addition to questions of an investigative nature, I also enjoy outreach and use of insects in outreach and education. Publications:

  • Dyer, L.A., Wagner, D.L., Greeney, H.F., Smilanich, A.M., Massad, T.M., Robinson, M. Fox, M., Hazen, R., Glassmire, A., Pardikes, N., Fredrickson, K., Pearson, C., Gentry, G.L., and J.O. Stireman III. 2012. Novel insights into tritrophic interaction diversity and chemical ecology using 16 years of volunteer supported research. American Entomologist 58:15-19.
  • Wagner, D. L., D. F. Schweitzer, J. B. Sullivan, and R. C. Reardon. 2011. Owlet Caterpillars of Eastern North America. Princeton University Press. 576 pp. (selected images)

Ania Truszczynski (amtruszczynski[at] I am a 5th year Population Biology PhD graduate student in Dr. Sharon Strauss’s lab at the University of California, Davis. I am working on applying phylogenetic tools to understanding the role of plant-insect interactions in plant community dynamics. Many models of community assembly do not explicitly include multi-trophic interactions. I am interested in integrating interactions with antagonists and mutualists as well as phylogenetic information into frameworks of community assembly. Currently, I am studying seed predators and pollinators on fifteen species in the family Asteraceae at Bodega Marine Reserve. For more information about my research, community outreach, and work with science communication, please see my website here.


Brian Anacker My research interests include plant community ecology, conservation biology, climate change, phylogenetics, and functional traits, especially regarding serpentine soils, coastal grasslands, and rare plants in California. I completed my PhD in Dr. Susan Harrison’s lab at the University of California, Davis, on habitat specialization and community assembly of plants on serpentine soils. In 2011, I completed a one-year postdoc with Dr. Harrison and the CA Dept. of Fish and Game (Biogeographic Data Branch) on climate change vulnerability of rare plants. Currently, I am a postdoc with Dr. Sharon Strauss at UC Davis. My work with Dr. Strauss is an experimental test of phylogenetic relatedness and ecological similarity at Bodega Marine Reserve on the Sonoma Coast of California. The research builds upon recent results showing shared germination preferences and higher adult competition among closely related plant species (ie congeners). Please see my website for more information: N. Ivalu Cacho (nicacho[at] I am an evolutionary biologist studying adaptation in rapidly evolving plant lineages.  I use phylogenetic methods, ecological experiments, and genomic approaches to address this topic.  My current research with Sharon Strauss focuses on the interplay between adaptation to stressful soil environments, investment in plant defense and competitive ability in the ecologically diverse Streptanthoid complex (Brassicaceae). In parallel, I am developing genomic approaches to infer phylogenies in clades that underwent rapid diversification. Other projects of mine include: – The origin and fate of what is potentially the only ring-species in plants: the Euphorbia tithymaloides species-complex in the Caribbean. – Floral evolution and cyathium development in Euphorbia. Read more in my website Lidia Caño ( I am a plant ecologist interested in patterns and processes that govern alien plant invasions. Invasion by alien species can serve as “natural experiments’’ that provide valuable information for the understandings of both community ecology and population biology. The study of alien species can also contribute to improve invasive species management. I completed my PhD at the University of Barcelona, Spain, on the ecological and evolutionary factors enhancing invasion by exotic Senecio spp. I joined Strauss’ lab in 2010 as a Fulbright Postdoctoral Fellow. My work with Sharon Strauss focuses on post-introduction selection on reproductive and dispersal traits in invasive mustards (Brassicaceae) and its role in invasive success. I am addressing this question by conducting experimental work comparing invasive vs. native populations of four species of mustards that are invasive in California. Other research interests of mine lie on the mechanistic understanding of ecological patterns of high-impact invasive species and its application to biodiversity conservation. I am currently investigating the invasion dynamics of the dioecious shrub Baccharis halimifolia that it is aggressively invading estuarine communities in Europe.                                                                                                                       Read more. Luke Mahler I’m interested in how ecological interactions shape the rate and pattern of macroevolutionary change. I mainly work on Anolis lizards, where I’ve investigated the influence of interspecific competition on rates of trait evolution, and the role of ecology in producing deterministic evolutionary outcomes, among other projects. I did my Ph.D. with Jonathan Losos at Harvard University, and in Fall 2011 I finished my degree and moved to California to take the CPB Postdoctoral Fellowship at UC Davis. Here I’m working with mentors Sharon Strauss, Brian Moore, and Peter Wainwright to investigate how a wide variety of species interactions affect diversification and trait evolution, mostly at broad phylogenetic timescales. For example, one project I’m involved in asks whether the evolution of a mutualistic association has influenced the rate of diversification in legumes. For more about my work, including recent publications, check out my website.


Katherine Wood Beginning July 2014, I will be a doctoral student at Michigan State University in Dr. Richard Kobe’s research group, studying in the Departments of Forestry (FOR) and Ecology, Evolutionary Biology, and Behavior (EEBB).

I am broadly interested the mechanisms that increase and maintain biodiversity of tropical forest communities across spatial and temporal scales. I am especially interested in investigating biotic interactions such as herbivory and competition, and abiotic factors such as soil nutrients and irradiance, in seedling and sapling establishment.

While completing a Bachelor’s Degree in Evolution, Ecology, and Biodiversity at the University of California – Davis, I worked with Dr. Sharon Strauss on a meta-analysis investigating herbivory in plant competitor removal experiments.  I also worked on a senior honors thesis with Dr. Marcel Rejmanek, investigating the Janzen-Connell Hypothesis at the Barro Colorado Island Research Station in Panama.

Email: woodkat7[at]


Emily Bergmann (embergmann[at] I am a UC Davis graduate with a background in Geology and Biological Anthropology. Post-graduation I became involved in plant research and have been hooked ever since. I am currently assisting Brian Anacker and Ivalu Cacho on their respective projects looking at plant community ecology at Bodega and relationships within the genus Streptanthus.


Caprice Lee (cmilee[at]  4892_119293480922_3526775_nI recently graduated from UC Davis with a Bachelor of Science degree in plant biology. Currently, I am assisting Brian Anacker and Ivalu Cacho on their respective projects and am in the process of applying to graduate programs for fall 2015.  As a native Californian, I grew up fascinated with this region’s Mediterranean plant communities. My research interests include plant-soil interactions, nutrient cycling, disturbance, restoration efforts, invasion biology and the effects of climate change factors on biodiversity in the California Floristic Province. With the Strauss Lab, I am beginning to work on projects regarding the roles of substrate, herbivory and competition in the generation of edaphic endemics. 

319846_3034879435292_97887082_nKen Zillig (kenzillig[at]  I graduated from Carleton College in Northfield, MN in 2013 with a Bachelor of Arts in Biology.  I am interested in factors that contribute to stable and resilient ecosystems, especially in marine systems and fisheries science.  To this end I am in the process of applying to graduate programs for the 2015 academic year.  As a tech in the Strauss lab I assist Brian Anacker with his research studying factors that moderate competition and coexistence of plant species at Bodega Bay.  I have also been working on an experiment to assess the influence of rhizobia on the coexistence of several native Trifolium species.