UC Davis doctoral candidate Lacie Newton covered two chapters of her dissertation when she recently delivered her exit seminar, in-person and via Zoom, on "Evolution and Speciation in the Trapdoor Spider Genus Aptostichus" in Briggs Hall. 

Newton studies with Professor Jason Bond, associate dean, College of Agricultural and Environmental Sciences, and the Evert and Marion Schlinger Endowed Chair in Insect Systematics, UC Davis Department of Entomology and Nematology.

"Spiders placed in the infraorder Mygalomorphae (tarantulas, trapdoor spiders and their kin) are generally recognized as an ancient cosmopolitan lineage that has persisted for over 250 million years," Newton wrote in her abstract. "Mygalomorph life history traits that include limited dispersal abilities, habitat specialization, and site fidelity altogether make them ideal organisms for studying speciation pattern and process, phylogeography, and adaptation. Evolutionary studies of mygalomorphs at both shallow and deeper phylogenetic levels have been limited prior to the advent of next generation sequencing approaches, with the majority of such studies relying on morphological characters or limited targeted locus approaches for phylogenetic reconstruction. Thus, it is imperative to implement larger genomic-scale datasets for confident reconstruction of relationships."

Her dissertation focuses 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. To address species boundaries in the A. unicolor species complex, she implemented genomic-scale data (that it, restriction-site associated DNA sequencing, RADseq) in conjunction with morphological, behavioral, and ecological data to evaluate cohesion species identity (Chapter I).

Similarly, assessing species boundaries in the Aptostichus icenoglei sibling species complex involved a target capture approach for subgenomic data (that is, ultraconserved elements, UCEs) and ecological data to evaluate genetic and ecological exchangeability, as per the cohesion species-based delimitation approach from a previous study (Chapter II).

"Lastly, to resolve interspecific relationships within Aptostichus, I used a sequence capture method (that is, UCEs) to generate molecular data in conjunction with morphological data for a combined-evidence phylogeny (Chapter III). These chapters all have the same overarching theme: to understand the forces underlying divergence between units of diversity and how those units are defined."

Newton expects to receive her doctorate by the end of summer and "then I will be heading to the American Museum of Natural History where I will be working in Jessica Ware's lab as a postdoctoral fellow on systematics of broader Odonata as well as Anisoptera (dragonflies)."

First-Generation College Student. Born and raised in Eupora, Miss., Lacie is a first-generation college student. She received her bachelor of science degree in biological sciences from Millsaps College in 2016 and then enrolled in the graduate school program at Auburn University, Alabama, studying with Professor Bond. When he accepted the Schlinger Endowed Chair in Insect Systematics in 2018, Lacie, along with other lab members, transferred to UC Davis.

What sparked her interest in spiders? “I actually used to be terrified of spiders,” Lacie acknowledged. “It wasn't until fall semester of my sophomore year when I took a zoology course that I began to appreciate not only the vast amount of diversity within spiders but also how amazing they are as a group, such as the tensile strength of spider silk being comparable to steel, spider venoms playing a role in potential medical applications, and a myriad of feeding strategies, etc..”

Her research on folding-door spiders or the Antrodiaetus unicolor species complex led to a journal article published in Molecular Ecology: “Integrative Species Delimitation Reveals Cryptic Diversity in the Southern Appalachian Antrodiaetus unicolor (Araneae: Antrodiaetidae) Species Complex.”  UC Davis co-authors are Professor Bond, who is the Evert and Marion Schlinger Endowed Chair in Insect Systematics, and project scientist James Starrett of the Bond lab.

Newton is active in both the American Arachnological Society  (AAS) and the Society of Systematic Biologists. She won a second-place award for her oral presentation on species delimitation at the 2019 AAS meeting, held at Washington and Lee University, Lexington, Va. 

At UC Davis, Newton served as a teaching assistant for the “Introduction to Biology: Biodiversity and the Tree of Life” course. Her resume also includes:

• mentoring undergraduate students in the Mentoring Program, Equity in Science, Technology, Engineering, Math, and Entrepreneurship (ESTEME) organization, a graduate student organization dedicated to improving equity and inclusion in STEM fields, entrepreneurship, and leadership positions.
• volunteering on the admissions committee for GOALS,  the Girls' Outdoor Adventure in Leadership and Science, a summer science program for high school students to learn science hands-on while backpacking through the wilderness.

AAS Conference at UC Davis. Newton is looking forward to the AAS conference, set June 26-30, at UC Davis, and will be assisting at the Eight-Legged Encounters open house from 1 to 4 p.m., June 25 at the Bohart Museum of Entomology, located in Room 1124 of the Academic Surge Building on Crocker Lane. The event will officially kick off the AAS meeting.

A "powerhouse" of arachnologists will be participating, said Bond, who will be hosting the conference with Lisa Chamberland, postdoctoral research associate, Department of Entomology and Nematology, and Joel Ledford, assistant professor of teaching, Department of Plant Biology, College of Biological Sciences.

Professor Eileen Hebets of the School of Biological Sciences, University of Nebraska, Lincoln, is co-hosting the open house as part of a U.S. National Science Foundation grant, “Eight-Legged Encounters” that she developed as an outreach project to connect arachnologists with communities, especially youth.

Some 20 exhibits and activities will be set up in the hallway of the Academic Surge Building, said Tabatha Yang, the Bohart Museum's education and outreach coordinator. “There will be everything--spider specimens, live arachnids, activities, artwork, etc.," Bond related.

Another highlight of the American Arachnological Society conference will be a series of public lectures, aimed for both novices and experts alike, on Tuesday, June 28, from 7:30 to 9, in the newly constructed 600-seat lecture hall, located in the campus core. The event is free and open to the public.