Profile story: UH Hilo molecular ecologist Natalie Graham studies arthropods found in the Hawaiian archipelago
Assistant Professor Graham investigates how the structure of biological communities change over time, in particular, how anthropogenic changes are altering species interactions and potentially driving communities past ecological tipping points.
By Susan Enright.
This post is an excerpt of Natalie Graham’s research profile on the website Keaohou that features UH Hilo faculty research and scholarly activity.
Natalie Graham is an assistant professor of biology at the University of Hawaiʻi at Hilo. A molecular ecologist, Graham’s primary research is in terrestrial arthropods found in the Hawaiian archipelago, which she studies to better understand what action should be taken to mitigate human impacts in the most vulnerable ecosystems. She does this through investigating how the structure of biological communities change over time, in particular, how anthropogenic changes are altering species interactions and potentially driving communities past ecological tipping points.
“I exploit the natural occurrence of age-structured terrains on the Hawaiian archipelago that represent communities in an assembly continuum at sites dating from 44 years to 5.5 million years in geological age,” says Graham about her work.
Graham received her master of science in biology from Sonoma State University, California, in 2014, and her doctor of philosophy in environmental science, policy, and management from University of California, Berkeley, in 2021. She arrived at UH Hilo in 2023, where she has founded the ʻElala Biodiversity Lab (ʻelala means insect in ʻōlelo Hawaiʻi, Hawaiian language). Graham also conducts research as an affiliate at Rausser College of Natural Resources at UC, Berkeley.
The research: Ecological and evolutionary dynamics
In a 2023 presentation, Graham explains the importance of researching ecological and evolutionary dynamics to understand how biodiversity accumulates through time. She says that interactions across space and time shape biodiversity, and while models have been developed to infer the dynamic processes shaping the evolution of communities, empirical data for understanding the interplay of ecology and evolution over long temporal scales are almost entirely lacking.
The Hawaiian archipelago provides an excellent backdrop for this research because each island is the result of the Pacific tectonic plate moving over a stationary “hot spot.” This means that each island began as a blank slate and represents a progressively longer amount of time that ecological and evolutionary processes have been able to shape present-day communities: younger islands tend to have communities with simpler networks and more generalized interactions (i.e., Hawaiʻi Island), while older islands have more established, complex, and specialized interactions (Kauaʻi).
Studying ecological genetics on islands with different geological development times has the potential to increase understanding of interactions between species, and how they have changed over time. Plant-arthropod interactions are an excellent model for this type of research because of the tremendous diversity in species and life histories, meaning scientists can find many more species and more specialized relationships between arthropods and plants.
Graham says that in her use of molecular tools to understand how biological communities are changing through time, her most significant contribution to the literature is the paper, Ecological network structure in response to community assembly processes over evolutionary time (Molecular Ecology, 2023). “This is a large, collaborative, empirical study using DNA metabarcoding (short sequences of DNA) which provides a profile of thousands of Hawaiian arthropods in communities across the geological time series,” she says. “There are more papers I am publishing soon about this research.”
- Learn more about this National Science Foundation-funded research project, Dimensions in Biodiversity, to which Graham contributed while a graduate student and then doctoral candidate. It was Graham’s doctoral dissertation work to do the data collection, DNA metabarcoding (sequencing) and statistical analysis on that research.
- See full list of Graham’s publications on her Google scholar page.
Current research
Since coming to UH Hilo, Assistant Professor Graham has wasted no time continuing her research.
Graham is a junior investigator for the Hawaiʻi Increasing Biomedical Research Excellence (HI INBRE V) program, a statewide federal project aimed at expanding the biomedical research capacity in Hawaiʻi.
“The research focus is the human, animal, and environmental health consequences of introduced arthropod pest species,” she says. “The methods include environmental DNA surveys for biosecurity and long-read sequencing for building genomic resources in Hawaiʻi.”
- Learn more about Graham’s overall research and her studies underway for the INBRE program, “Island Ecosystems as Crucibles for Invasion Genomics and One Health Training of Undergraduates in Biomedicine.”
Graham also is working with a UH Hilo SEED Money Grant of intramural funding awarded in the spring of 2024 to investigate how arthropod and plant communities are shifting when the forest is hit with high rates of the pathogen that causes Rapid ʻŌhiʻa Death, a fungal disease that has killed hundreds of thousands of mature ʻōhiʻa trees (Metrosideros polymorpha) throughout the Hawaiian Islands. ROD is caused by two invasive fungi, Ceratocystis huliohia and Ceratocystis lukuohia, and has the potential to irreversibly change some native Hawaiian ecosystems.
“I will use the SEED grant and my INBRE research data to apply for additional funds to continue to understand forest ecosystems in Hawaiʻi and how they are changing over time,” she says.
Graham is currently working on building a DNA barcode reference library for arthropods of the Hawaiian Islands. This would generate DNA sequences for the major endemic insects and also the major pest species.
“This DNA reference library will help with my community level analyses as well as ongoing work of others to understand bird and bat diets, and other species interactions,” explains Graham. “For example, I am using DNA sequencing of arthropod communities to capture their biotic associations (species interactions) with plants across spatial, temporal, and disturbance gradients. I am also using environmental DNA (eDNA) sampling as a means to quickly determine species interactions, for example, molecular spider gut content analysis or pollination studies from washing flowers for eDNA.”
Graham is also currently experimenting with how eDNA can be used for rapid assessment of ecosystem health to keep up with fast changing community composition such as invasive species or species turnover, or rapidly changing abiotic (climate) variables.
Read Assistant Professor Graham’s full profile at the UH Hilo research website Keaohou.
Story by Susan Enright, a public information specialist for the Office of the Chancellor and editor of UH Hilo Stories. She received her bachelor of arts in English and certificate in women’s studies from UH Hilo.
