- Author: Kathy Keatley Garvey
The top honors went to:
- Doctoral candidate Shawn Christensen and doctoral student Alexia "Lexie" Martin, both of the lab of associate professor and community ecologist Rachel Vannette, vice chair of the department; and
- Doctoral student Iris Quayle of the lab of professor and arachnologist Jason Bond, the Evert and Marion Schlinger Endowed Chair and associate dean, College of Agricultural and Environmental Sciences.
Christensen competed in the Plant-Insect Ecosystems (P-IE) Section, Apiculture; Martin in the P-IE Section, Pollinator Biology; and Quayle in the Systematics, Evolution, and Biodiversity (SysEB) Section, Biogeography.
Shawn Christensen. Christensen presented "Bee Specific! Solitary Bee (Anthophora bomboides) Hosts a Specialized Core Microbiome through Development."
His abstract: "Host-microbe interactions are important for the development and fitness of many macroorganisms. While social bees are dependent on a vertically transmitted gut microbiome, solitary bees, which comprise the vast majority of species diversity within bees, lack a specialized gut community. We explored the microbiome associated with the complete life cycle of the ground-nesting polylectic solitary bee Anthophora bomboides standfordiana, including bacterial and fungal composition and abundance. In contrast to expectations, we found that immature stages of this solitary bee maintain a distinct core microbiome consisting of Actinobacteria and one yeast species. Stage-specific shifts in microbial abundance and community composition occur most notably during bee diapause, during which the abundance of bacteria and fungi increased dramatically. We tested two adaptive hypotheses regarding the role of the microbiome in bee ecology. First, isolated brood cell Streptomyces strains were found to inhibit growth of multiple often pathogenic filamentous fungi, suggesting a role in pathogen protection during the long period of diapause. Second, sugar alcohol composition changed in tandem with major changes in microbial abundance suggesting links with bee metabolism or overwintering biology. Our results suggest that this Anthophora species hosts a conserved core microbiome that may provide key fitness advantages through larval development and overwintering. Much work remains to examine the nature of bee-microbiome ecology, but our study reframes the conditions thought to promote the evolution and maintenance of symbiosis."
Co-authors: Rachel Vannette and Sriram Srinivas, UC Davis; Quinn McFrederick, UC Riverside; Bryan Danworth, Cornell University; and Stephen Buchmann, University of Arizona
Her abstract: "Bees interact with and in some cases benefit from a diverse community of microbes, which can be obtained through intraspecific interactions or the environment. Due to differences in sociality, bee species vary in their main route of microbial acquisition and their dependence on microbes. Despite the observation that intraspecific transmission of microbes is imperfect and environmental microbes are nearly ubiquitous in flowers, the potential impacts of intraspecific versus floral microbes on overall pollinator health have not been evaluated. This study uses two model bee species - one social (Bombus impatiens) and one solitary (Osmia lignaria)--to assess the establishment and health impacts of floral and intraspecific microbes. 2x2 factorial experiments were performed on B. impatiens microcolonies and O. lignaria females to selectively introduce intraspecific microbes and/or floral microbes. Survivorship and reproduction were measured to assess bee health and fitness, and DNA extractions and amplicon sequencing were performed on bee guts to evaluate microbial establishment. The results of this study will inform how microbes from different acquisition routes establish in the host, shape the gut microbiome, and affect host health. Since many macroorganisms encounter both intraspecific and environmental microbes, this study provides a framework for similar work in other organisms."
Co-author: Rachel Vannette, UC Davis
Her abstract: "In the Namib Desert, one of the largest and oldest deserts, the genus Onymacris contains a rarity for darkling beetles (Tenebrionidae) – the presence of eight species with striking ‘white' elytra (ranging from stark white to tan/striped). This study seeks to examine the phylogenetic relationships among white Onymacris species to test whether multiple derivations of white elytra is due to convergence or introgression. Population genomic data (3RAD) was generated from all white species of Onymacris with intraspecific sampling for four widespread species (O. marginipennis, O. bicolor, O. candidipennis, O. langi cornelii). Phylogenetic trees were inferred from 995 loci using concatenated and coalescent-based methods. The analyses supported two clades: langi and bicolor each of which contain species with pure white elytra. Variational autoencoder (VAE) clustering analysis shows a pattern of genetically isolated populations (bicolor) and gene flow indicating introgression (langi). These analyses also infer a potential new Angolan species sister to O. marginipennis in need of evaluation. Ancestral character state and biogeographic reconstruction resolve the timing of white species' color expression against the backdrop of sand sea emergence and increased aridity in the Namib, a landscape renown for ‘pocket speciation' and an impressive amount of darkling beetle diversity accounting for nearly 80% of the known endemic beetle fauna. Dynamic coloration provides a fascinating system through which to examine the role of ecological pressures and evolutionary mechanisms but requires a phylogenetic framework to understand organisms' potential adaptations to extreme environments, which is increasingly vital in the face of global trends aridity trends."
Co-authors: Lisa Chamberland, James Starrett and Jason Bond, UC Davis
The full list of student winners--first, second and third places--is here.
Founded in 1889, ESA is the largest entomological organization in the world. Its more than 7,000 members are affiliated with educational institutions, health agencies, private industry, and government.
- Author: Kathy Keatley Garvey
The doctoral students are Grace Horne, who studies with urban landscape entomologist Emily Meineke, assistant professor; Alexia “Lexie" Martin, who studies with community ecologist Rachel Vannette, associate professor; and Marshall Nakatani, who studies with bee scientist Brian Johnson, associate professor.
The undergraduate recipient is entomology major Mingxuan “Gary” Ge, a research scholar in the campuswide Research Scholars Program in Insect Biology (RSPIB), co-founded and administered by faculty in the UC Davis Department of Entomology and Nematology. He is advised by community ecologist and professor Louie Yang of the UC Davis Department of Entomology and Nematology (and a RSPIB co-founder), and UC Davis distinguished professor and lepidopterist Art Shapiro of the Department of Evolution and Ecology.
Each recipient will receive a five-year fellowship providing three years of financial support, inclusive of an annual stipend of $37,000.
The NSF-GRFP is the most prestigious award of its type. The annual acceptance rates are about 16 percent from among more than 12,000 annual applicants. The awards are given to outstanding graduate students who have demonstrated “the potential to be high-achieving scientists and engineers early in their careers.”
Grace Horne, Meineke Lab
Grace Horne, who grew up in Marlborough, N.H., is a 2021 graduate of Colby College, Waterville, Maine, where she double-majored in biology (evolution and ecology), and environmental science (conservation biology), receiving magna cum laude (with distinction) in both majors. Horne, who joined the Meineke lab in 2021, studies plant-insect interactions, urban ecology, global change biology, natural history and community science.
Horne submitted this successful proposal:
Working title: "Natural History Collections for Backcasting Plant-Insect Interactions in a Changing World."
Description: "Herbivory by caterpillars can have negative impacts on plant survival, growth, and reproduction. Interactions between plants and caterpillars, which are both metabolically tied to temperature, are particularly consequential for ecosystems. However, investigations of how species have and will interact under a changing climate are lacking. In particular, insects are in decline in many areas, but the downstream effects of insect herbivore losses and simultaneous climate change on plants are unclear. Thus, I propose to combine modern observations, a controlled experiment, and data cached in natural history collections to investigate effects of climate change on plant-insect interactions in a biodiversity hotspot."
Lexie Martin, a native of Cypress, Texas, is a 2021 graduate of the University of Texas, Austin, where she received her bachelor of science degree in biology, with a concentration in ecology, evolution and behavior, and a bachelor of science and arts in chemistry. She graduated with research distinction and as a dean's honored graduate. Martin's research interests include bees, mutualism, bee-microbe interactions, bee diversity, plant-pollination interactions, conservation and bee health. Her career plans are to pursue a professor position at a university, to continue researching bee-microbe interactions and other factors affecting bee health. Martin submitted this successful proposal
Title: "Effects of Intraspecifically Transmitted Versus Environmentally Acquired Microbes on Bees."
Description:"Although most social organisms can obtain microbes through intraspecific and environmental acquisition routes, few studies have directly compared how microbial acquisition route affects host health. In this project, I am investigating how microbes in the bee core gut microbiota vs. microbes obtained from flowers establish within the gut and affect the overall health of bumblebees (Bombus impatiens) and blue orchard bees (Osmia lignaria). I selectively introduced microbes obtained through each route to bees and will be measuring establishment within the gut, survivorship, fitness, and lipid stores. The results of this project will be applicable to other social organisms, as well as relevant to the management of commercial bees and crops."
Marshall Nakatani, from Lansdale, Pa., is a 2021 graduate of George Washington Univeristy, where he received his bachelor of science degree in biology, with a concentration in cell and molecular biology. He is in his second year as a UC Davis doctoral student. Nakatani's general interests include eusociality, the division of labor in social insects, and how genetics and the environment interact to determine phenotype. His career plans: to continue working in academia.
Nakatani submitted this winning proposal:
Gary Ge, Yang Lab and Shapiro Lab
In his project, he uses the American Apollo butterfly (Parnassius clodius) as a model to study how microclimatic conditions affect cold-adapted insects. P. clodius, a white butterfly, is found at high elevations in western United States (Washington, Oregon, Nevada and Canada) and in British Columbia, Canada.
“The genus Parnassius is prone to global warming due to its affinity for alpine and arctic habitats, and several species are considered to be threatened,” Ge wrote in his winning proposal. “The American Apollo has habitats ranging from coastal forests to above the tree line. Thus, they experience very different combinations of microclimatic variations depending on time and location. Unlike most other butterflies, their larvae develop under cold macroclimatic temperatures and demonstrate active behavioral thermoregulation. This makes them highly dependent and consequently sensitive to microclimatic temperatures. In addition, the adults are poor dispersers, limiting gene flow between spatially close populations. Their larvae are also likely the sole insect herbivore of the host plant species, thus microhabitat identification is easy in the field.”
“I hypothesize that mid-elevation populations of P. clodius have the best cold tolerance as overwintering eggs," Ge wrote in his proposal. "The main factor behind this is snow cover. Snow cover is known to provide significant insulation to whatever is underneath, usually creating higher microclimatic temperatures under the snow than above. At mid-elevations, the winter temperatures are lower than at low elevations, and the snow cover is supposedly less and more unstable compared to higher elevations. This means the mid-elevation populations are likely exposed to the coldest winter temperature, and have locally adapted to it.”
A recent update: After data analysis, Ge and Yang found significant difference between supercooling points of the eggs from two P. clodius populations and it is in line with Ge's hypothesis. The higher elevation population has higher SCP (less cold tolerant), and the lower elevation population has lower SCP (more cold tolerant).”
Shapiro, who has monitored butterfly populations across central California for the last 50 years, notes that “Parnassians are a group of cold-adapted Northern Hemisphere butterflies that are becoming increasingly important as objects of physiological, ecological and evolutionary study. They are only likely to grow more important in the context of climate change. Thus, Gary's study is very timely and should attract plenty of attention! It is demanding given the rigorous conditions in which they breed and develop, and he is likely to learn a lot that will facilitate future lab and field studies.”
Ge's project also factored in his winning the 2023 Dr. Stephen Garczynski Undergraduate Research Scholarship from the Pacific Branch, Entomological Society of America.
GRFP's Mission. GRFP aims to “ensure the quality, vitality, and diversity of the scientific and engineering workforce of the United States,” according to its website, and to “broaden participation in science and engineering of underrepresented groups, including women, minorities, persons with disabilities, and veterans.” Applicants must be pursuing full-time research-based master's and doctoral degrees in science, technology, engineering, and mathematics (STEM) or in STEM education at accredited U.S. institutions." The list of recipients is here.
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