Jessica Gillung's Research on Spider Flies: A Tale of Conflict and Uncertainty

When UC Davis doctoral candidate Jessica Gillung, who studies the parasitoid flies commonly known as spider flies, presents her exit seminar on Friday, Dec. 14, it's bound to draw widespread interest.

Her research already has.

She just won the prize for best student presentation at the recent 9th International Congress of Dipterology in Windhoek, Namibia.

Gillung delivered her presentation on “Phylogenetic Relationships of Spider Flies (Acroceridae) – Discordance, Uncertainty and the Perils of Phylogenomics.” Acrocerid adults are floral visitors, and some are specialized pollinators, while the larvae are internal parasitoids of spiders.

Approximately 350 delegates attended the conference; the scientists focus on the Diptera order, which includes houseflies, mosquitoes, and gnats. Gillung was among 40 students presenting their research.

Gillung studies with major professor Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology, UC Davis Department of Entomology and Nematology; mentor Shaun Winterton of the California Department of Food and Agriculture; and collaborator Phil Ward, UC Davis professor of entomology.

UC Davis doctoral students Charlotte Herbert Alberts and Socrates Letana, who both study with Kimsey, also presented their work; Alberts delivered an oral presentation on her research (she studies Asilidae (Assassin flies), and Letana displayed a poster on bot flies.

Presenting the award to Gillung was Professor Thomas Pape of the Natural History Museum of Denmark and chair of the Council for the International Congresses of Dipterology, which organizes the conferences. The next Congress takes place in 2022 in California.

In her abstract, Gillung described spider flies “as a monophyletic group of lower Brachycera currently classified into three subfamilies, 55 genera and ca 530 species.”

“The group has long been considered a rogue taxon and its placement within the Diptera tree of life remains uncertain,” she wrote. “Phylogenetic relationships among lineages of spider flies are by contrast relatively well established, with hypotheses proposed based on molecular data from both Sanger and high-throughput sequencing. Phylogenomic estimation of spider fly relationships yields different topologies, depending on whether data is coded and analyzed as nucleotides or as amino acids. The most significant difference among the two data types is in the monophyly of Panopinae; a morphologically and ecologically recognizable group, that is recovered as monophyletic only in the analyses of nucleotides. This study uses Acroceridae as a system to explore the effects of potential confounding factors in phylogenomic reconstruction. This research takes advantage of modern and powerful statistical approaches, including posterior predictive simulation, to understand the effects of conflict, uncertainty and systematic error in the estimation of evolutionary relationships using the standard phylogenomic toolkit.”

Fast forward to her exit seminar, which she will deliver at 2 p.m., Friday, Dec. 14 in 122 Briggs Hall, located off Kleiber Hall Drive. The title:  “Evolution of Fossil and Living Spider Flies (Diptera, Acroceridae): A Tale of Conflict and Uncertainty."

"Parasitoid flies," Gillung wrote in her abstract for her Dec. 14 seminar, "are some of the most remarkable, yet poorly known groups of insects. Represented by over 10,000 species distributed in 21 families, dipteran parasitoids comprise over 100 independent lineages, offering an unparalleled system to understanding the origin, evolution and diversification of the parasitoid life history. My dissertation research unraveled the systematics, evolution and biology of a lineage of dipteran parasitoids specialized in spiders, Acroceridae, commonly known as spider flies. My research resulted in a monograph of fossil spider flies, and a robust hypothesis for the pattern and timing of spider fly evolution based on high throughput sequencing. Through the combination of DNA sequence data obtained via Sanger sequencing with morphological characters, I also estimated their relationships among spider fly genera using an extensive taxon sampling which culminated in a new taxonomic classification for the family.”

Gillung has accepted a postdoctoral position at Cornell University, Ithaca, beginning Jan. 2. She will be working with Bryan Danforth on Apoidea (stinging wasps and bees) phylogenomics, evolution and diversification.

She recently was named the recipient of the prestigious 2018 Student Leadership Award, presented by the Pacific Branch, Entomological Society of America (PBESA), which represents 11 states, seven U.S. territories, and parts of Canada and Mexico.

 A native of Brazil, Jessica holds a bachelor's degree in biology from the Federal University of Paraná, Curitiba, Brazil and a master's degree in zoology from the University of São Paulo, Brazil. She speaks four languages fluently: Portuguese, Spanish, English and German.