- Author: Kathy Keatley Garvey
The three-hour open house included displays of live ants as well as specimens. Ward and newly minted PhDs, Jill Oberski and Zachary Griebenow of the Ward lab, fielded scores of questions. Oberski and Griebenow each wore a "Dr." name tag, presented by Tabatha Yang, Bohart Museum education and outreach coordinator.
"The questions were mostly about the habits and behavior of ants, how many species are there, etc.," Ward related. "And how can I obtain live colonies for my kid? I received almost no queries about 'how do I get rid of them in my kitchen?' and that was refreshing."
"We had live colonies of a centipede-hunting ant (Stigmatomma oregonense) and a generalist omnivore (Aphaenogaster occidentalis)," Ward said. "The displays also included collections of common California ants; the world's smallest ant (Carebara) and the world's largest ant (Myrmecia)."
Griebenow, who recently presented his exit seminar on "Systematic Revision of the Ant Subfamily Leptanillinae (Hymenoptera:Formicidae), Reciprocally Illuminated by Phylogenomics and Morphology," answered questions about his research, and general questions about ant diversity. Griebenow, who holds a bachelor of science degree (2017) in agriculture (entomology), magna cum laude, from The Ohio State University, joined the Ward lab in September 2017.
Oberski, who received her bachelor's degree in biology and a bachelor's degree in German studies (summa cum laude) in 2016 from Macalester College, Saint Paul, Minn., finished her dissertation earlier this month. She will present her exit seminar on "Phylogenetics and Biography of Pyramid Ants" at 4:10 p.m., Wednesday, June 7 in 122 Briggs Hall. It also will be on Zoom.
Questions at the open house? Oberski shared that she received "some great questions about ant diets. What do ants eat? Are ants specialized or generalized in their feeding habits? The answer can vary a lot. Some ants are generalists that eat any food they come across, but others are extremely specific, like ants that are fungus farmers or specialized predators of springtails, spider eggs, or centipedes."
Professor Ward is featured in a Bohart Museum of Entomology video on YouTube at https://youtu.be/d8eRNsD8dxo. Ants, he related, originated about 120 million years ago (early Cretaceous), evolving from "wasp-like creatures." They are members of the order Hymenoptera, and their closest relatives include honey bees, cockroach wasp and the mud daubers. California is home to some 300 species of ants, but thousands more live in the tropics. Globally, there may be as many as 40,000 to 50,000 species of ants, the professor estimated, but only about 14,000 are described.
Also in the video, Ward related that ants live in long-lived colonies with (1) cooperative brood care (2) overlapping generations and (3) reproductive division of labor, the hallmarks of eusocial behavior. He also pointed out:
- A typical ant colony contains a reproductive queen, numerous non-reproductive workers and brood (eggs, larvae, pupae)
- Colonies of ants can be thought of as superorganisms: tightly integrated and cooperative entities with complex systems of communication and division of labor (castes)
The Bohart Museum, directed by UC Davis distinguished professor Lynn Kimsey, houses a global collection of eight million insects and also maintains a live "petting zoo" (Madagascar hissing cockroaches, stick insects, tarantulas and others) and an insect-themed gift shop. The museum is located in Room 1124 of the Academic Surge Building, 455 Crocker Lane.
The next Bohart Museum open house, themed "Insects and Forensics," will be from 1 to 4 p.m., Saturday, June 3. It will feature forensic entomologist Robert "Bob" Kimsey and his work.
- Author: Kathy Keatley Garvey
Her seminar takes place at 3:30 in 366 Briggs Hall, and also will be on Zoom.
Mack studies Aedes aegypti with a focus on analysis of transcriptomic datasets and 3D imaging datasets. "Throughout my time in graduate school, my projects have considered pyrethroid resistance in Aedes aegypti ;examining the genetic response to this insecticide. As I finish up my dissertation, I hope to pursue a career in industry using the skills I've developed to continue to analyze large datasets!"
Insecticide resistance is a global issue, Mack says in her exit seminar abstract. Ae. aegypti, known as "the yellow fever mosquito," can transmit dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. The mosquito was first colonized California in 2013 and arrived resistant to pyrethroids. "The pyrethroid target site genotype differs geographically in California and partially infers resistance phenotype, indicating that other mechanisms are at play as well."
"Since their detection in 2013, Aedes aegypti has become a widespread urban pest in California," the co-authors wrote in the abstract. "The availability of cryptic larval breeding sites in residential areas and resistance to insecticides pose significant challenges to control efforts. Resistance to pyrethroids is largely attributed to mutations in the voltage gated sodium channels (VGSC), the pyrethroid site of action. However, past studies have indicated that VGSC mutations may not be entirely predictive of the observed resistance phenotype."
"To investigate the frequencies of VGSC mutations and the relationship with pyrethroid insecticide resistance in California, we sampled Ae. aegypti from four locations in the Central Valley, and the Greater Los Angeles area. Mosquitoes from each location were subjected to an individual pyrethrum bottle bioassay to determine knockdown times. A subset of assayed mosquitoes from each location was then analyzed to determine the composition of 5 single nucleotide polymorphism (SNP) loci within the VGSC gene."
The conclusion:
"Resistance associated VGSC SNPs are prevalent, particularly in the Central Valley. Interestingly, among mosquitoes carrying all 4 resistance associated SNPs, we observe significant heterogeneity in bottle bioassay profiles suggesting that other mechanisms are important to the individual resistance of Ae. aegypti in California."
Mack, who holds a bachelor of science degree (2018) in biology from Creighton University, Omaha, Neb., enrolled in the UC Davis graduate school program in 2018.
Active in the Entomological Society of America, Mack scored second place in student competition at the 2022 joint meeting of the Entomological Societies of America, Canada, and British Columbia, held last November in Vancouver, British Columbia. She entered her presentation, "Three Dimensional Analysis of Vitellogenesis in Aedes aegypi Using Synchrotron X-Ray MicroCT,” in the category, "Graduate School Physiology, Biochemistry and Toxicology: Physiology.
Her abstract: "Traditional methods of viewing the internal anatomy of insects require some degree of tissue manipulation and/or destruction. Using synchrotron-based x-ray phase contrast microCT (pcMicroCT) avoids this issue and has the capability to produce high contrast, three dimensional images. Our lab is using this technique to study the morphological changes occurring in the mosquito Aedes aegypti during its reproductive cycle. Ae. aegypti is the primary global arbovirus vector, present on all continents except Antarctica. Their ability to spread these viruses is tightly linked with their ability to reproduce, as the production of eggs in this species is initiated by blood feeding. Amazingly, this species produces a full cohort of eggs (typically 50-100) in just 3 days' time following a blood meal. This rapid development represents dramatic shifts in physiological processes that result in massive volumetric changes to internal anatomy over time. To explore these changes thoroughly, a time course of microCT scans were completed over the vitellogenic period. This dataset provides a virtual representation of the volumetric, conformational, and positional changes occurring in tissues important for reproduction across the vitellogenic period. This dataset provides the field of vector biology with a detailed three-dimensional internal atlas of the processes of vitellogenesis in Ae. aegypti."
"As for career plans, I am applying to computational biology positions in industry," Mack said. "I'm not filing my dissertation until July so I am still working on this."
- Author: Kathy Keatley Garvey
Her major professor Jason Bond, then a professor and administrator at Auburn University, Alabama, described and named what is commonly called "The Barack Obama Trapdoor Spider" in 2012.
The article, published in the journal Ecology and Evolution and part of Newton's 2022 doctoral dissertation, is titled "Phylogeography and Cohesion Species Delimitation of California Endemic Trapdoor Spiders within the Aptostichus icenoglei Sibling Species Complex (Araneae: Mygalomorphae: Euctenizidae)."
Co-authors are Professor Bond, who is the Evert and Marion Schlinger Endowed Chair in the UC Davis Department of Entomology and Nematology, and associate dean, College of Agricultural and Environmental Sciences; and Bond lab members, project scientist James Starrett and doctoral candidate Emma Jochim.
"Species delimitation in mygalomorph spiders using only traditional morphological approaches has underestimated species diversity," Newton said, "yet molecular approaches have been shown to overestimate species diversity due to the local population structuring seen as 'species divergence.' Specifically, the Aptostichus icenoglei complex, which comprises the three sibling species, A. barackobamai, A. isabella, and A. icenoglei, exhibits evidence of cryptic mitochondrial DNA diversity throughout their ranges across the California Floristic Province."
The researchers sampled 62 individuals overall for the three species within the complex, using both specimens from Bond (2012) and new records. "A. barackobamai was collected across its geographic range in northern California for a total of 21 samples, and A. icenoglei was collected throughout its range in southern California for a total of 40 samples," they wrote. "Only one specimen of A. isabella was included in this study due to collecting constraints (i.e., only one individual of this species has ever been collected and a burrow has not yet been found containing this species; Bond, (2012)
Next steps? "We hope to use whole genomes for both reconstructing evolutionary relationships as well as identifying genes that contribute to potential adaptive divergence across the landscape," Newton said. "We also hope to gather more natural history data for each of the species, especially A. icenoglei populations, for general ecological information that may aid in species delimitation."
Born and raised in Eupora, Miss., and a first-generation college student in her family, Lacie holds a bachelor of science degree in biological sciences (2016) from Millsaps College, Jackson, Miss. She then enrolled in the graduate school program at Auburn University, studying with Professor Bond. When he accepted the Schlinger Endowed Chair in 2018, Lacie, along with other lab members, transferred to UC Davis. Newton completed her dissertation on species delimitation in two trapdoor spider groups, Antrodiaetus unicolor complex and Aptostichus icenoglei sister species complex, and evaluation of interspecific relationships within the genus Aptostichus.
The research drew support from a National Science Foundation Grant awarded to Bond and Starrett; the McBeth Memorial Scholarship awarded to Newton; and the Evert and Marion Schlinger Foundation.
- Author: Kathy Keatley Garvey
Postema studies the role of animal coloration in predator-prey interatctions with a special focus on color-changing species. She works with both live and artificial swallowtail caterpillars (family Papilionidae) in the field.
She is the lead author of a review article, "Color Under Pressure: How multiple Factors Shape Defensive Coloration," published in June 2022 in the journal, Behavioral Ecology.
The abstract: Behavioral ecologists have long studied the role of coloration as a defense against natural enemies. Recent reviews of defensive coloration have emphasized that these visual signals are rarely selected by single predatory receivers. Complex interactions between signaler, receiver, and environmental pressures produce a striking array of color strategies—many of which must serve multiple, sometimes conflicting, functions. In this review, we describe six common conflicts in selection pressures that produce multifunctional color patterns, and three key strategies of multifunctionality. Six general scenarios that produce conflicting selection pressures on defensive coloration are: (1) multiple antagonists, (2) conspecific communication, (3) hunting while being hunted, (4) variation in transmission environment, (5) ontogenetic changes, and (6) abiotic/physiological factors. Organisms resolve these apparent conflicts via (1) intermediate, (2) simultaneous, and/or (3) plastic color strategies. These strategies apply across the full spectrum of color defenses, from aposematism to crypsis, and reflect how complexity in sets of selection pressures can produce and maintain the diversity of animal color patterns we see in nature. Finally, we discuss how best to approach studies of multifunctionality in animal color, with specific examples of unresolved questions in the field."
On the Yang lab website, Postema says: "After growing up in Ann Arbor, MI, I relocated to Denison University in Granville, OH to pursue my undergraduate degree. Though I began my college career as a studio art major, I quickly found that biology was my calling. I studied a wide range of systems throughout college, from lemon sharks and rock iguanas to deciduous shrubs. I am now conducting research on insect color and behavior in the Animal Behavior program at UC Davis. When I'm not obsessing over bugs, I can usually be found spoiling my pet chickens, drawing sketches for The Ethogram, or writing poetry."
At UC Davis, Postema is a member of the Animal Behavior Graduate Group.
"Elizabeth will be starting a great postdoc position studying beetle coloration at the Field Museum in Chicago," Professor Yang announced.
- Author: Kathy Keatley Garvey
She will present her seminar at 4:10 p.m. in Room 122, Briggs Hall. Her seminar also will be virtual. The Zoom link: https://ucdavis.zoom.us/j/95882849672
Her abstract: “Neurons have two types of cellular projections, that are essential for how they function in circuits: they have a single axon and a highly branched network of dendrites. These dendrites are the cellular structures that allow neurons to receive input from the environment or from other neurons. While much is known about how axons respond to injury, almost nothing is known about how neurons respond to dendrite injury. We have found that after dendrite injury, peripheral nervous system neurons are able to mount a reliable, reproducible process of dendrite regeneration. In this talk, I present our recent work to determine how neurons detect injury to their dendrites, using the larvae and adult fruit fly Drosophila melanogaster as a model to study dendrite regeneration.”
A pre-seminar coffee takes place from 3:30 to 4:10 in Briggs 158.
Thompson-Peer, who joined UC Irvine in April 2019, received her bachelor's degree in biology from the University of Pennsylvania, and then followed with a two-year stint at the Johns Hopkins University with Alex Kolodkin. She earned her doctorate from Harvard University, working with Josh Kaplan, and was a postdoctoral fellow with Yuh-Nung and Lily Jan at UC San Francisco and the Howard Hughes Medical Institute. Her postdoctoral work drew financial support from the National Institute of Neurological Disorders and Stroke F32 and K99/R00 fellowships, as well as a UC Office of the President's Postdoctoral Fellowship.
The Thompson-Peer lab explores how neurons recover from injury in vivo, and how this process is similar to and different from normal development. (See her work on YouTube)
"At the most fundamental level, a neuron receives information along dendrites, and sends information down an axon to synaptic contacts," she writes on her website. "Dendrites can be injured by traumatic brain injury, stroke, and many forms of neurodegeneration, yet while the factors that control axon regeneration after injury have been extensively studied, we know almost nothing about dendrite regeneration. Our long-term research goal is to understand the cellular mechanisms of dendrite regeneration after injury."
"Our previous work found that the sensory neurons in the fruit fly Drosophila peripheral nervous system exhibit robust regeneration of dendrites after injury and used this system to explore central features of dendrite regeneration in developing animals, young adults, and aging adults. We have observed that after injury, neurons regrow dendrites that recreate some features of uninjured dendrites, but are unable to reconstruct an entire arbor that perfectly mimics an uninjured neuron. Moreover, there are mechanistic differences between the outgrowth of uninjured neurons versus the regeneration of dendrites after injury: dendrite regeneration is uniquely dependent on neuronal activity, ignores cues that constrain and pattern normal dendrite outgrowth, and confronts a mature tissue environment that is different from what a developing neuron would encounter. These challenges are significantly exacerbated when neurons in aging animals attempt to recover from injury."
Department seminar coordinator is urban landscape entomologist Emily Meineke, assistant professor. For technical issues regarding Zoom connections, she may be reached at ekmeineke@ucdavis.edu. (See complete list of spring seminars.)