About

Rosemary Gillespie is a Professor in the Department of Environmental Science, Policy & Management at the Rausser College of Natural Resources. Her research focuses on understanding evolutionary patterns and processes among populations and species, with a primary emphasis on islands, particularly remote hotspot islands of the Pacific. Her work leverages the geological history of archipelagoes, such as the Hawaiian islands, to examine how communities have changed over time and to gain insights into the processes shaping communities over evolutionary periods. By studying islands with well-understood geological histories, she investigates early stages of diversification and community formation, comparing these across different islands and archipelagoes. Her research interests include evolutionary ecology, systematics, spider biology, and conservation.

Research topics

• Biology
• Computer Science
• Ecology
• Environmental resource management
• Telecommunications
• Environmental planning
• Evolutionary biology
• Computational biology

Selected publications

• Amphibians' Expansion to Record Elevations Influences Chytrid ( <scp> <i>Batrachochytrium dendrobatidis</i> </scp> ) Infection Dynamics

  Biotropica · 2026-02-23

  articleOpen access

  ABSTRACT The climate‐driven range expansion of host species could impact emerging infectious disease events through several mechanisms, with repercussions for conservation and public health. For instance, infection outcomes may be affected by the different responses of hosts and pathogens to new environments. Additionally, range expansions may create novel transmission opportunities as host movement patterns change. Here, we use an integrative approach to explore how the infection dynamics of Marbled four‐eyed frogs ( Pleurodema marmoratum ) with the pathogen Batrachochytrium dendrobatidis ( Bd ) have been impacted by their elevational range expansion in the Cordillera Vilcanota, Peru. With field surveys, we establish that range expansion created new opportunities for Bd transmission: P. marmoratum are now continuously distributed along a recently deglaciated mountain pass between populations separated by heavily glaciated mountains. With sequence data, we identify Bd from the Vilcanota as belonging to the lineage most frequently associated with amphibian declines ( Bd GPL) and find that it lacks genetic structure despite possessing abundant variation, consistent with high rates of local dispersal. With temperature loggers, we demonstrate that upslope expansion exposed frogs and Bd to challenging new thermal regimes. Finally, with size, mass, and Bd infection data from adult P. marmoratum , we find that the new elevations colonized may constrain infection intensities and influence sublethal costs of infection: at low elevations, infected frogs have lower body condition than uninfected frogs, while at high elevations, infected frogs have smaller bodies than uninfected frogs. Together, our results suggest that the climate‐driven range shifts of host species may influence pathogen transmission and infection outcomes.

  PublisherDOI

• Rapid ecological and evolutionary divergence during a poleward range expansion

  Ecological Monographs · 2026-02-01

  articleOpen access

  Abstract Understanding how species distributions respond to environmental change is a key question in ecology and evolution. While many species are shifting their ranges, the mechanisms driving the extent and rate of these shifts, and the consequences of their establishment in a novel environment, are often poorly understood. Particularly interesting groups of organisms to study in this context are those that have shifted their distributions faster than warming average temperatures alone can explain. Our study investigates whether adaptation to colder temperatures in novel northern environments—and associated life history trade‐offs across different life stages—explains this apparent mismatch between climate change and the pace of range expansion. Unlike many range‐expanding taxa, our focal species, the wasp spider Argiope bruennichi , disperses passively via ballooning, and as a generalist mesopredator, its expansion is not limited by host plant availability and can exert significant bottom‐up and top‐down ecosystem effects, making it of particular interest. We integrated analyses of adult phenology, morphology, offspring cold tolerance, and genome‐wide variation to test which traits are likely driven by adaptation to colder conditions or whether phenotypic plasticity drives the rapid northward expansion. Females matured earlier at smaller sizes at the range edge. The lack of a concurrent reduction in fecundity suggests that genetic adaptation plays a role. Hatched juveniles that overwintered in their egg sacs were subjected to a reciprocal common garden experiment that simulated either core or edge winter temperatures. Edge‐origin spiderlings exhibited lower overall overwinter survival, but the surviving ones had lower lethal temperatures and enhanced supercooling ability than their core‐origin counterparts. Furthermore, metabolomic profiles revealed that cold stress‐induced accumulation of amino acids and myo‐inositol likely contributes to improved cold tolerance. A genome‐wide analysis delineated two distinct genetic clusters across Europe, separated by central Germany, and showed that genetic variation is linked to winter climate and seasonality gradients. Overall, our data support genetic differentiation as a major driver of the observed differences, coupled with considerable phenotypic plasticity. Our integrated approach underscores the necessity of assessing trait evolution across life stages to understand how organisms overcome climatic barriers, thus elucidating the mechanisms underlying rapid range expansion.

  PublisherDOI

• Comparison of environmental DNA and bulk DNA metabarcoding for assessing terrestrial arthropod diversity across three habitat types on Guam

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-02-04 · 1 citations

  articleOpen access

  Abstract DNA based methods offer a rapid and cost-effective way for detecting species occurrence and monitoring biodiversity; among them bulk DNA metabarcoding is well-established, and recently developed environmental DNA (eDNA)-based methods offer a non-destructive alternative. With a goal to develop suitable methods for assessing insect biodiversity in ecosystems for which DNA reference libraries are not well developed and incomplete, such as remote islands, we compared established bulk DNA metabarcoding methods with eDNA across three replicated terrestrial ecosystem types (limestone forest, degraded forest, and grassland) in Guam. Using two mitochondrial COI primer pairs, we performed bulk DNA metabarcoding of standard entomological collection methods (malaise traps, pan traps, vegetation beating), and compared the assessment of biodiversity with that from different eDNA sources (flowers, spider webs, leaves, tree trunks). In our samples, eDNA and bulk DNA metabarcoding both detected a large proportion of overall taxa (OTUs, 86.6% and 60.3%, respectively). Although DNA metabarcoding detected significantly more taxa, eDNA proved to be a reasonable non-destructive alternative. As expected, because of limitations in existing reference databases for remote habitats, species-level identification was achieved for only a few OTUs. Overall, the sampling approach was the dominant driver of arthropod diversity, explaining ∼17% of the observed variation, while habitat type accounted for ∼4%. Thus, each sampling approach captured some unique diversity signals and contributed to the complementary effect of maximizing detection. For rapid insect biodiversity surveys of terrestrial arthropods, we recommend an integrated metabarcoding approach, and in sensitive habitats where insect capture is undesirable, eDNA offers a powerful alternative to monitor diversity and community change.

  PublisherDOI

• 2007 ESPM C107, IB 158LF Biology and Geomorphology of Tropical Islands Class

  iPlaces-Kotahi · 2026-03-17

  otherOpen access

  The sources consist of final research papers from the 2007 University of California, Berkeley course titled Biology and Geomorphology of Tropical Islands. The class took place on the island of Moorea, French Polynesia, with students based at the Richard B. Gump South Pacific Research Station. Throughout the course, participants engaged in original scientific inquiry by designing and executing independent research projects across marine, freshwater, and terrestrial environments. These studies addressed a wide array of topics, including the behavior of marine mollusks and hermit crabs, the distribution of invasive plant species like falcata trees and Lantana, the thermoregulatory needs of local lizards, and the ecological succession of invertebrates in decomposing Tahitian chestnut fruit. Methodologically, students utilized field surveys involving transects and quadrats, laboratory manipulations, and technical tools such as geographic information systems (GIS) and statistical analysis software to evaluate their data. The class served as a platform for students to explore complex biological interactions and environmental issues, such as the impact of agricultural runoff on stream diatoms and the role of various organisms in the tropical carbon cycle

  PublisherDOI

• 2008 ESPM C107, IB 158LF Biology and Geomorphology of Tropical Islands Class

  iPlaces-Kotahi · 2026-03-17

  otherOpen access

  The UC Berkeley class ESPM 107/IB 158, also known as Biology and Geomorphology of Tropical Islands, was conducted in Moorea, French Polynesia, in late 2008. Students in the class performed field-based investigations across a wide range of ecological and biological topics, including marine community metabolism, the impact of invasive species on native flora, and the behavior of island fauna like hermit crabs and spiders. Research also addressed human-driven environmental changes, such as the effects of agricultural runoff on planktonic shrimp and the influence of ecotourism on pink whipray populations. The academic structure of the class involved students developing hypotheses, gathering data through transects, quadrats, or lab experiments, and conducting statistical analyses to test their findings. These projects were supported by UC Berkeley faculty and staff at the Richard B. Gump South Pacific Research Station.

  PublisherDOI

• Topography structures of arthropod communities revealed by leaf-derived environmental DNA on O’ahu, Hawai’i

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-04-10

  articleOpen access

  Abstract Arthropod communities on oceanic islands are shaped by spatial isolation, environmental gradients, and biological invasions, yet their structure remains difficult to resolve due to incomplete taxonomic coverage. In particular, it remains unclear (i) how non-native arthropods can influence community composition and (ii) how they interact with native and non-native plants. To answer the first question, we used leaf-derived environmental DNA (eDNA) to characterize arthropod communities across elevational gradients on five ridges on O’ahu, using the native tree Metrosideros polymorpha as a standardized plant. To understand the second question, we compared leaf-derived eDNA from Metrosideros polymorpha (Native), Acacia koa (native), and Psidium cattleianum (invasive), co-occurring in two ridges on O’ahu. Additionally, to overcome limitations of reference databases, we applied NIClassify to infer native versus introduced status without requiring species-level identification. Across 96 leaf samples (with 851 Arthropod ASVs), we found arthropod richness increased with elevation, while the proportion of introduced taxa declined significantly. Community composition was primarily structured by ridge, with strong distance–decay relationships indicating high spatial turnover in both native and non-native assemblages. In contrast, plant species effects were context dependent and did not show a consistent native versus invasive signal. Threshold analyses identified a community transition (native vs introduced) near 500 m elevation. These results show that plant-derived eDNA can resolve spatial and environmental structuring of arthropod communities while capturing invasion dynamics under incomplete taxonomic knowledge. Classifier-based inference enables community-level ecological interpretation beyond reference-limited taxa, providing a scalable framework for biodiversity monitoring in data-poor systems.

  PublisherDOI

• 2004 ESPM C107, IB 158LF Biology and Geomorphology of Tropical Islands Class

  iPlaces-Kotahi · 2026-03-17

  otherOpen access1st authorCorresponding

  The Moorea Class of 2004 was a semester-long undergraduate course from the University of California, Berkeley, officially known as Biology and Geomorphology of Tropical Islands. The class consisted of twenty students who traveled to the island of Moorea in French Polynesia to conduct original research projects. Based at the Richard B. Gump South Pacific Biological Research Station, the students spent nine weeks in the field after three weeks of preparation in Berkeley. Research topics were diverse, encompassing terrestrial and marine biology, botany, and geomorphology. The program was designed as a research expedition, involving planning, field reconnaissance, and the design and implementation of individual scientific studies. Upon returning to Berkeley, the students presented their results at a public research symposium and produced written papers. These papers were compiled and published in Volume 13 of the Moorea Student Papers series. The course was led by a team of faculty members and Graduate Student Instructors with expertise in various scientific disciplines.

  PublisherDOI

• 2005 ESPM C107, IB 158LF Biology and Geomorphology of Tropical Islands Class

  iPlaces-Kotahi · 2026-03-17

  otherOpen access

  The 2005 Moorea Class, officially titled Biology and Geomorphology of Tropical Islands, is a semester-long undergraduate course offered by the University of California, Berkeley. The program begins with three weeks of intensive study and preparation on the Berkeley campus before students travel to the island of Moorea in French Polynesia. Based at the Richard B. Gump South Pacific Research Station, students transition from lecture halls to professional scientific investigation by designing and executing original research projects in diverse habitats such as coral reefs and tropical forests. During the final weeks of the semester, students return to Berkeley to finalize their work, deliver presentations at a public research symposium, and publish their findings in a series of research books.

  PublisherDOI

• Invasive Spiders and Their Microbiomes: Patterns of Microbial Variation in Native and Invasive Species in Hawai'i

  Ecology and Evolution · 2025-10-01

  articleOpen accessSenior authorCorresponding

  ABSTRACT Invasive species can have detrimental impacts on the community structure and native species persistence, causing cascading impacts on ecosystem function. These effects are amplified in remote island ecosystems that are characterized by non‐representative and often diverse biota. The mechanisms behind successful invasions, particularly of arthropods, are varied, but growing evidence suggests that invasive species escape from their native predators and competitors. Recent research has suggested that gut microbiota can play an important role in arthropod fitness, with vertically transmitted endosymbionts and horizontally acquired microbes performing different functions. Here, we explored the extent to which the microbiome may facilitate the ability of spiders to exploit and ultimately adapt to novel environments. We examined co‐occurring pairs of native and invasive spiders across three locations in the Hawaiian Islands and compared them with mainland counterparts to test two core predictions: (1) gut microbiota would be shaped primarily by local environmental filters rather than invasion status, and (2) vertically transmitted endosymbionts would show stronger host‐specificity and reduced diversity in invasives. Using 16S rRNA amplicon sequencing, we found that the site explained 11.7% of gut‐microbial compositional variance compared to 6.5% for host species. These results suggest that each spider maintains a species‐specific level of α‐diversity but reassembles taxonomic composition according to local microbial pools, thus indicating high context dependence in environmental filtering. Invasive species were found to have a lower relative abundance of gut endosymbiont taxa, with one species, Badumna longinqua , showing little to no endosymbiont presence across sites, and the other, Steatoda grossa , exhibiting low but site‐specific abundance. We observed a strong localization effect, suggesting that these endosymbionts are also being acquired from local environments, not carried from ancestral ranges. These results suggest host–symbiont interactions have differential impacts on native and invasive species and that microbiota may facilitate the success of spiders in novel environments.

  PublisherOA PDFDOI

• Leaving the Web: Testing the Link between Predation Style and Resting Metabolic Rate Using Closely Related Spiders with Contrasting Lifestyles

  SSRN Electronic Journal · 2025-01-01

  preprintOpen accessSenior author
  PublisherDOI

Recent grants

• Collaborative Research: CalBug, an Interactive Database Using Arthropods to Examine Impacts of Climate Change and Habitat Modification

  NSF · $993k · 2010–2016

• Dimensions: Collaborative Research: A community level approach to understanding speciation in Hawaiian lineages

  NSF · $1.2M · 2013–2019

• Survey of Terrestrial Arthropods of French Polynesia

  NSF · $556k · 2005–2010

• Track 2, GK-12: Exploring California Biodiversity

  NSF · $2.1M · 2006–2013

• Genomics of repeatedly evolving color diversity in the polymorphic Hawaiian happy face spider

  NSF · $705k · 2009–2016

Frequent coauthors

• Henrik Krehenwinkel

  Universität Trier

  51 shared

• Hannah M. Wood

  National Museum of Natural History

  40 shared

• George Roderick

  University of California, Berkeley

  33 shared

• Charles E. Griswold

  California Academy of Sciences

  33 shared

• Susan Kennedy

  Universität Trier

  33 shared

• Stefan Prost

  University of Oulu

  32 shared

• Michael S. Brewer

  East Carolina University

  30 shared

• Evan P. Economo

  Okinawa Institute of Science and Technology Graduate University

  27 shared

Education

• PhD, Zoology

  University of Tennessee Knoxville

  1986