About

Victoria Sork is a Distinguished Professor and the Director of the UCLA Mathias Botanical Garden and Herbarium within the Department of Ecology and Evolutionary Biology. Her research program examines the evolution of tree populations in relation to their local environment, focusing on gene flow, natural selection, and demographic history. She has selected trees, particularly oaks such as Quercus lobata (valley oak), as a key study system due to their ecological importance, long lifespan, high population sizes, and conservation relevance. Her work involves creating high-quality, annotated genomes and conducting landscape and ecological genomics, transcriptomic, and epigenetic studies to understand local adaptation, gene movement, phylogeography, hybridization, and introgression in oak species. She explores how physical landscape features and climate cycles shape genetic lineages and how interspecific gene flow contributes to genetic variation. Her research integrates genetic patterns across multiple scales, from single nucleotides to landscapes, with the goal of informing conservation policies and management strategies to enhance the survival of tree species amid changing environments.

Research topics

• Ecology
• Environmental resource management
• Biology
• Sociology
• Geography
• Environmental planning
• Genetics
• Psychology
• Mathematics education
• Pedagogy

Selected publications

• Persistent climate maladaptation decreases performance of a keystone tree species ( <i>Quercus lobata</i> )

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-02-07 · 2 citations

  articleOpen accessSenior authorCorresponding

  Abstract Maladaptation in foundational tree species can undermine ecosystem stability, but few studies have quantified its current magnitude or its consequences under ongoing climate change. Using a range-wide provenance test of valley oak ( Quercus lobata ), we tested whether historical climate warming has already produced temperature-driven climate–fitness mismatches, whether climatic extremes intensify these mismatches, and whether understanding these patterns can inform management. Growth and survival models from a 12-year common garden study revealed that trees performed best under summer temperatures cooler than their home climates, demonstrating persistent maladaptation to contemporary temperature maxima. This mismatch intensified during hotter years, indicating that climate variability amplifies fitness costs and that stressful years impose lasting effects. However, simulations of assisted gene flow showed that sourcing seeds from high-performing maternal families yields greater projected future performance than climate-matched sourcing across the species’ range. Together, these findings provide rare phenotypic evidence that maladaptation is already constraining a keystone tree species and show that phenotype-informed management can outperform climate-matched seed sourcing under further temperature increases.

  PublisherOA PDFDOI

• Applying Both Landscape Genomic and Ecological Niche Model Predictions to Inform Conservation Strategies of a California Foundational Oak Species

  Molecular Ecology · 2026-03-31 · 1 citations

  articleOpen accessSenior authorCorresponding

  Environmental factors shape the distributions of organisms and their underlying patterns of genetic variation. When climate changes rapidly, organisms that are adapted to current environments may become maladapted to future climates. Long-lived tree species are especially susceptible to climate maladaptation due to their sessile nature and long generation times. Understanding how foundational tree species will respond to future climate, both in adaptive ability and distribution shifts, is imperative for effective management and conservation of tree populations and the ecosystems they comprise. Here, we used whole genome sequences from 163 individuals of blue oak (Quercus douglasii) to determine predicted adaptedness, the degree to which an organism can survive and reproduce in future climate, based on landscape genomic models, compare those genomic predictions with ecological niche model predictions, and propose seed sourcing and restoration site strategies to increase the adaptedness of stands at preserves managed by The Nature Conservancy. Both ecological and genomic models predict that blue oak stands will be more susceptible to future climate along the Sierra Nevada basin, with patches of higher climate adaptedness along the central coast of California. To test whether management practices could increase adaptedness of blue oak stands, we examined the impact of seed source and restoration site choice on future stands. Regardless of restoration site category, our expectation held true that future maladaptation risk is reduced the most when using seed sources preadapted to the future climate of the restoration site. However, restoration sites containing stands with high habitat suitability and high climate adaptedness always did best. We conclude that strategic conservation and management strategies utilizing seed transfer from climate-adapted stands may improve the future health of blue oak stands susceptible to future climate.

  PublisherDOI

• Landscape Genomic Analyses of <i>Quercus agrifolia</i> Née Predict Patterns of Adaptedness to Future Climate and Provide Guidance for Conservation

  Evolutionary Applications · 2026-04-01 · 1 citations

  articleOpen accessSenior authorCorresponding

  ABSTRACT Habitat destruction and climate change are two primary drivers of global biodiversity loss. Many contemporary ecological preserves and preserve networks are designed to protect species and the ecological and evolutionary processes that will maintain future biodiversity. However, it is challenging to identify where to locate preserves and how to manage them to meet these goals. One emerging conservation tool is landscape genomics, which allows us to identify populations that may be maladapted to future climate and thereby helps prioritize areas for acquisition (areas of high adaptedness), restoration (areas of low adaptedness), and management. Here, using whole genome sequence data of 171 adult trees, we studied the climate adaptedness of California populations of coast live oak ( Quercus agrifolia ), a foundation species that broadly supports biodiversity, to develop a conservation management strategy, including direct acquisition, land management, and restoration that addresses the predicted impact of future climate. Over the range of coast live oak, we find that the northernmost and southernmost stands are predicted to be more at risk for maladaptation to climate change, with the central coast of California containing stands with high adaptedness, including in unprotected areas that might benefit from protection. Using three large preserves (focal sites) managed by The Nature Conservancy (TNC), we illustrate how moving seeds from low to high elevation parts of preserves could benefit future populations range‐wide by increasing overall climate adaptedness. We discuss the different levels of risk across focal sites and apply our interpretations into TNC's 400,000 + −acre conservation holdings in California to sustain future populations of this foundational tree species. This study represents a unique collaboration between academic and applied conservation scientists to both assess levels of maladaptedness of a foundational tree to predicted climate change and also develop a genomic‐informed seed transfer program to improve adaptedness of future populations.

  PublisherDOI

• Drought-associated genes exhibit high constitutive expression in <i>Quercus douglasii</i> , a drought tolerant California oak

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-07-08

  preprintOpen accessSenior authorCorresponding

  Abstract Drought stress is a strong selective pressure for all plant species. Plants can respond to water shortage through various strategies that confer drought tolerance, but with a potential cost for growth. These strategies may be plastic responses that occur with the onset of stress or may comprise continuously-expressed (constitutive) traits regardless of water availability. Here, we used RNA-Seq to characterize transcriptional responses to dehydration in seedlings of a drought tolerant oak, Quercus douglasii , from a population in the Sierra Nevada Foothills in California. In the greenhouse, we subjected 24 seedlings from six maternal families to dry-down or well-watered treatments and prepared RNA libraries from tissue collected before and after each treatment (48 libraries). Our goals were to characterize the pattern of up- and down-regulated genes in response to dehydration and to assess the extent to which this drought tolerant species shows differential versus constitutive expression as a drought response strategy. We identified few differentially expressed genes in response to dehydration. Up-regulated genes were related to known drought response functions, while down-regulated genes were enriched for gene ontology terms related to growth and carbohydrate metabolism. We discovered high constitutive expression of many putatively drought-responsive genes that had been found to exhibit gene expression plasticity in a drought sensitive oak, which a novel finding for drought tolerance strategies in tree species. We conclude that the drought tolerant strategy of Q. douglasii incorporates high constitutive expression levels of drought-responsive genes, as well as some plasticity in its response once environmental stress is experienced.

  PublisherOA PDFDOI

• Ancient Introgression Shapes Evolutionary History of a California Channel Island Relictual Species, Island Oak (Quercus Tomentella)

  SSRN Electronic Journal · 2025-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Current maladaptation increases with age in valley oak ( <i>Quercus lobata</i> ): Implications for future populations

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-07-11

  preprintOpen accessSenior author

  Abstract Adaptation and maladaptation are two fundamental evolutionary processes shaping the success of tree populations. Local adaptation has been studied extensively, but maladaptation, which not simply be the inverse, is particularly important for long-lived species since human impact is changing the environment on a very short time scale. Because maladaptation may be observed at different stages of an organism’s life cycle, temporal variation may reduce or enhance the vulnerability of a species to a new climate environment. In this paper, we use findings from an ongoing range-wide provenance study comprising two common gardens of 3,674 half-sib juvenile valley oaks ( Quercus lobata ) from 658 maternal families to address two objectives. First, we test whether maladaptation (a) persists as trees age and/or (b) varies in magnitude over time. We model growth rates and performance measures (height * survival; “performance”) across families sourced from sites with differing climates. Second, we assess the extent to which evidence-based seed transfer can mitigate the impact of maladaptation. We find that the twelve-year-old trees are currently adapted to temperatures not only cooler than their home site, but also beyond the coolest limit of the current species range. Moreover, this maladaptive pattern is exacerbated in hotter years of our study. Despite a general pattern of maladaptation, we demonstrate the feasibility of using phenotype-informed seed transfer guidelines for replanting trees in current populations by identified high-performing individuals from varied environmental origins. Overall, our results indicate that valley oak is imperiled by current and future climate conditions, but high-performing trees well suited to sites across the species range can be identified as seed donors. We conclude that current maladaptation in a long-lived tree species is a major threat that is first apparent within a few years and worsens as trees age, but careful management of vulnerable oak populations can improve their resiliency.

  PublisherOA PDFDOI

• Ancient introgression shapes the evolutionary history of a California Channel Island relictual species, island oak (Quercus tomentella)

  Global Ecology and Conservation · 2025-06-23 · 3 citations

  articleOpen accessSenior authorCorresponding

  Hybridization, a common phenomenon among plants, can result in the exchange of neutral or beneficial genetic loci, potentially leading to adaptive introgression. It is often difficult to know whether the genetic composition of contemporary species is the result of recent hybridization or reflects ancient introgression, but examination of a species long separated from a congener provides the opportunity to study ancient introgression. Here, we investigate the rare and endangered island oak (Quercus tomentella ) that is relictual on the California Channel Islands but was once sympatric with canyon live oak (Q. chrysolepis) on the mainland. Recent studies have shown that contemporary populations of island oak include many individuals with essentially 50% shared co-ancestry between the two species, but very few individuals of non-admixed canyon live oak on any island. The goal of this study is to assess the extent to which the genetic composition of island oak reflects ancient introgression with canyon live oak when they were sympatric on the mainland at least 2.6 - 7 million years ago. We used evolutionary demographic models that identify the presence and timing of bottleneck events and the extent and timing of ancient introgression between island oak and canyon live oak. Bidirectional gene flow was found throughout their evolutionary history, suggesting that hybridization is not a recent development and may have introduced adaptive alleles into ancient populations that still persist today.

  PublisherDOI

• Drought-associated genes exhibit high constitutive expression in <i>Quercus douglasii</i> , a drought-tolerant California oak

  G3 Genes Genomes Genetics · 2025-12-12 · 1 citations

  articleOpen accessSenior author

  Drought stress is a strong selective pressure for all plant species. Plants respond to water shortage through various strategies that confer drought tolerance. These strategies may be plastic responses that occur with the onset of stress or may comprise continuously expressed (constitutive) traits regardless of water availability. Here, we used RNA-seq to characterize transcriptional responses to dehydration in seedlings of a drought-tolerant oak, Quercus douglasii, from a local population in the Sierra Nevada Foothills in California. In the greenhouse, we subjected 24 seedlings from 6 maternal families to dry-down or well-watered treatments and prepared RNA libraries from tissue collected before and after each treatment (48 libraries). Our goals were to characterize the pattern of up- and downregulated genes in response to dehydration and to assess the extent to which this drought-tolerant species shows differential versus constitutive expression as a drought response strategy. We identified few differentially expressed genes in response to dehydration. Upregulated genes were related to known drought response functions, while downregulated genes were enriched for gene ontology terms related to growth and carbohydrate metabolism. We discovered high constitutive expression of many putatively drought-responsive genes that had been found to exhibit gene expression plasticity in a different oak species, which is drought-sensitive. This novel finding demonstrates the potential for constitutive expression of genes involved in drought stress to provide an additional mechanism of drought tolerance for some tree species, such as Q. douglasii.

  PublisherOA PDFDOI

• Drought tolerance is associated with constitutive gene expression, not plasticity, across California oak species

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-08-22 · 1 citations

  preprintOpen accessSenior author

  - Drought is a major stressor for plants globally. Variation in gene expression patterns across species can provide critical evidence for the genomic basis of drought tolerance. - We paired comparative transcriptomics with functional trait measurements to identify genomic mechanisms associated with drought tolerance across six species from three oak clades in California, including a pair of species within each clade representing relatively mesic or xeric environments. We tested how plastic and constitutive gene expression patterns varied among species with contrasting drought tolerance traits. We also tested whether gene expression responses were decoupled from phylogenetic history, suggesting they have evolved multiple times as adaptations to species climate niches. - Species with drought-tolerant traits exhibited lower levels of gene expression plasticity during leaf dehydration than drought-sensitive species, but showed signatures of positive selection on constitutive gene expression. Drought-sensitive species across clades converged in their patterns of plastic gene expression during dehydration, diverging from their more closely related drought tolerant species, suggesting that repeated evolution has shaped plastic gene expression responses to drought. - Drought-tolerant oak species have evolved constitutive gene expression alongside drought tolerant functional traits, while drought-sensitive oak species have evolved similar plastic gene expression responses to drought.

  PublisherOA PDFDOI

• Maladaptive response of an endemic California oak to climatic warming is previewed by interannual variation in growth and survival

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-12-21

  preprintOpen accessSenior authorCorresponding

  Abstract Climate change poses a major threat to long-lived tree populations by shifting environmental conditions away from those to which species are adapted. One of the biggest concerns is that individuals that are adapted to current conditions will become maladapted to new conditions due to a reduction in fitness. If tree populations are already maladapted to their current environments, climate change may put them at even greater risk. Valley oak ( Quercus lobata ), a foundational California endemic tree species, has already lost much of its range to anthropogenic activities and has been shown to demonstrate patterns of climatic maladaptation. Given the rapid pace of climate change, predicting the future of a species requires quantifying the extent to which contemporary populations are adapted or maladapted to current climates. Here, we tested the extent and variability of maladaptation in valley oak using a ten-year, range-wide provenance study of 3,371 half-sib juvenile trees from 658 maternal lineages. We compared growth rates and multiplicative fitness functions (height * survival; MFF) across families sourced from sites with differing climates relative to the gardens, as well as against annual phenological records. We found evidence that valley oak trees are most adapted to temperatures beyond the coolest limit of the current species range. Within and across years, trees sourced from hotter localities had higher growth and fitness in the gardens, and the relationship was more pronounced in hotter years. Trees showed persistent maladaptation after ten years, suggesting that the role of phenotypic plasticity in immediate environmental response is superseded by underlying genotypes. Finally, trees with earlier leaf phenology (associated with warmer source climates) consistently showed higher growth rates, further demonstrating a maladaptive pattern. Our results suggest that short-term variation in fitness shows immediate short-term response to climate warming, “previewing” a concerning range of species-level responses to increasing temperature.

  PublisherDOI

Recent grants

• REU: Genetic Structure within Oak Populations

  NSF · $214k · 1989–1992

• Sequencing and Annotating the Valley Oak Genome

  NSF · $2.0M · 2015–2020

• Collaborative research: Seed-flow in California Valley Oak (Quercus lobata)--Novel Approaches to an Old Problem

  NSF · $706k · 2005–2011

• Collaborative Research: Landscape Patterns of Pollen Movement in Declining Populations of California Valley Oak, Quercus Lobata

  NSF · $251k · 2001–2002

• Consequences of Pollen Source and Fruit Abortion on Progeny Fitness in Cassia Fasciculata (Environmental Science)

  NSF · $102k · 1985–1987

Frequent coauthors

• Paul F. Gugger

  University of Maryland Center for Environmental Science

  41 shared

• Peter E. Smouse

  Rutgers, The State University of New Jersey

  39 shared

• Delphine Grivet

  37 shared

• Douglas G. Scofield

  Uppsala University

  32 shared

• Jian‐Li Zhao

  Yunnan University

  22 shared

• Sorel Fitz‐Gibbon

  University of California, Los Angeles

  21 shared

• Joaquín Ortego

  Estación Biológica de Doñana

  18 shared

• Qingjun Li

  Shandong University of Traditional Chinese Medicine

  18 shared

Education

• Ph.D., Ecology and Evolutionary Biology

  University of California, Los Angeles

  2005

• M.S., Ecology and Evolutionary Biology

  University of California, Los Angeles

  2001

• B.A., Environmental Science

  University of California, Los Angeles

  1999