About

John Hellmann is a professor of English at Ohio State University-Lima. He holds a PhD from Kent State University, an MA from the University of Louisville, and a BA from the University of Louisville. He is the author of three books focusing on post-World War II American literature, film, and culture: 'Fables of Fact: The New Journalism as New Fiction,' 'American Myth and the Legacy of Vietnam,' and 'The Kennedy Obsession: The American Myth of JFK.' His essays have been published in journals such as American Quarterly, Genre, Critique, and American Literary History. Hellmann has received a year-long grant from the American Council of Learned Societies and has been awarded Senior Fulbright Lectureships to teach at the University of Antwerp in Belgium and the University of Bonn in Germany. He has also served as an invited lecturer at the University of Wales, Swansea. Recently, he authored essays on Kennedy and postwar intellectual culture and on the New Hollywood Cinema, and he is currently writing a book on cinema and the 1960s.

Research topics

• Biology
• Genetics
• Zoology
• Ecology
• Developmental psychology
• Demography
• Psychology

Selected publications

• Chronic predation risk induces sex-specific effects in behavior but does not induce long-term oxidative damage

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-02-24

  articleOpen accessSenior author

  ABSTRACT Predation is a strong environmental and selective pressure that can favour rapid and plastic shifts in behaviour and escape ability to increase an organism’s immediate survival. However, maintaining antipredator responses under repeated predation stress can induce physiological costs to an organism from long-term exposure to elevated cortisol. We know little about how individuals balance this trade-off between short-term survival and longevity, including whether males and females balance this trade-off differently based on life history differences in reproduction, survival, and risk adversity. To assess sex differences in long-term behavioural responses and physiological costs to predation risk, we exposed threespine stickleback ( Gasterosteus aculeatus ) to visual cues of a live rainbow trout ( Oncorhynchus mykiss ) predator twice a week for 14 weeks, then measured stickleback antipredator behaviour and swimming performance 5 months later. To quantify potential long-term costs of behavioural adaptation, we measured relative telomere length as a proxy for long-term oxidative damage. We found strong sex specific effects in behaviour and swim endurance: males, but not females, altered their hiding behaviour and had shorter swim endurance in the first trial, suggesting overall lower activity. Surprisingly, we found no evidence for chronic predation shortening telomere length or hindering growth in body length. Overall, these results suggest that plastic responses can be dictated by the different life-history strategies for males and females, and suggest that individuals can maintain long-term changes in antipredator behaviour without costs to their physiological state. Highlights Chronic predator exposure produced persistent sex differences in space use and swim performance. Predator-exposed males altered their hiding strategy and showed reduced swim performance, while females showed no behavioural or performance differences. Differences in swim times were restricted to the first trial and all individuals were exhausted by trial 3. Relative telomere length and growth in length did not differ between exposed and unexposed individuals.

  PublisherDOI

• Warm waters undermine cryptic female choice

  DRYAD · 2026-01-09

  datasetOpen access

  (1) Understanding the thermal sensitivity of reproductive interactions is crucial given global warming. Previous studies have almost exclusively focused on interactions before mating, even though important interactions between the sexes also occur after mating (e.g., gamete interactions), which are likely affected by temperature. (2) Thus, it remains unknown how temperature affects the influence of female reproductive fluid on sperm performance, thereby altering female control over fertilization (cryptic female choice). This gap limits our understanding of how sexual selection changes with seasonal temperature fluctuations and temperatures outside the range of historical norms. (3) We tested how temperatures relevant to current conditions and climate change projections influence the mechanisms underlying cryptic female choice in a marine fish, Symphodus ocellatus. Under typical thermal conditions, female reproductive fluid enhances sperm velocity and biases fertilization dynamics to favor preferred, dominant males over sneaker males. (4) We find that warmer temperatures decrease female influence on sperm velocity, especially for dominant males. This results in dominant males having slower sperm than sneaker males at warmer temperatures, reducing the expected paternity of preferred, dominant males. (5) Our results highlight that considering the thermal sensitivity of female-male interactions that occur after mating will be essential for understanding how seasonal variation and climate change can influence fertility, reproduction, and sexual selection.

  PublisherDOI

• Warm waters undermine cryptic female choice

  Zenodo (CERN European Organization for Nuclear Research) · 2026-01-15

  otherOpen access

  (1) Understanding the thermal sensitivity of reproductive interactions is crucial given global warming. Previous studies have almost exclusively focused on interactions before mating, even though important interactions between the sexes also occur after mating (e.g., gamete interactions), which are likely affected by temperature. (2) Thus, it remains unknown how temperature affects the influence of female reproductive fluid on sperm performance, thereby altering female control over fertilization (cryptic female choice). This gap limits our understanding of how sexual selection changes with seasonal temperature fluctuations and temperatures outside the range of historical norms. (3) We tested how temperatures relevant to current conditions and climate change projections influence the mechanisms underlying cryptic female choice in a marine fish, Symphodus ocellatus. Under typical thermal conditions, female reproductive fluid enhances sperm velocity and biases fertilization dynamics to favor preferred, dominant males over sneaker males. (4) We find that warmer temperatures decrease female influence on sperm velocity, especially for dominant males. This results in dominant males having slower sperm than sneaker males at warmer temperatures, reducing the expected paternity of preferred, dominant males. (5) Our results highlight that considering the thermal sensitivity of female-male interactions that occur after mating will be essential for understanding how seasonal variation and climate change can influence fertility, reproduction, and sexual selection.

  PublisherDOI

• Warm waters undermine cryptic female choice

  Functional Ecology · 2026-01-28 · 1 citations

  articleOpen access

  Abstract Understanding the thermal sensitivity of reproductive interactions is crucial given global warming. Previous studies have almost exclusively focused on interactions before mating, even though important interactions between the sexes also occur after mating (e.g. gamete interactions), which are likely also affected by temperature. Thus, it remains unknown how temperature affects the influence of female reproductive fluid on sperm performance, thereby altering female control over fertilization (cryptic female choice). This gap limits our understanding of how sexual selection changes with seasonal temperature fluctuations and temperatures outside the range of historical norms. We tested how temperatures relevant to current conditions and climate change projections influence the mechanisms underlying cryptic female choice in a marine fish, Symphodus ocellatus . Under typical, cooler thermal conditions, female reproductive fluid enhances sperm velocity and biases fertilization dynamics to favour preferred, dominant males over sneaker males. We find that warmer temperatures decrease female influence on sperm velocity, especially for dominant males. This results in dominant males having slower sperm than sneaker males at warmer temperatures, reducing the expected paternity of preferred, dominant males. Our results highlight that considering the thermal sensitivity of female–male interactions that occur after mating will be essential for understanding how seasonal variation and climate change can influence fertility, reproduction and sexual selection. Read the free Plain Language Summary for this article on the Journal blog.

  PublisherOA PDFDOI

• Warm waters undermine cryptic female choice

  Zenodo (CERN European Organization for Nuclear Research) · 2026-01-15

  otherOpen access

  (1) Understanding the thermal sensitivity of reproductive interactions is crucial given global warming. Previous studies have almost exclusively focused on interactions before mating, even though important interactions between the sexes also occur after mating (e.g., gamete interactions), which are likely affected by temperature. (2) Thus, it remains unknown how temperature affects the influence of female reproductive fluid on sperm performance, thereby altering female control over fertilization (cryptic female choice). This gap limits our understanding of how sexual selection changes with seasonal temperature fluctuations and temperatures outside the range of historical norms. (3) We tested how temperatures relevant to current conditions and climate change projections influence the mechanisms underlying cryptic female choice in a marine fish, Symphodus ocellatus. Under typical thermal conditions, female reproductive fluid enhances sperm velocity and biases fertilization dynamics to favor preferred, dominant males over sneaker males. (4) We find that warmer temperatures decrease female influence on sperm velocity, especially for dominant males. This results in dominant males having slower sperm than sneaker males at warmer temperatures, reducing the expected paternity of preferred, dominant males. (5) Our results highlight that considering the thermal sensitivity of female-male interactions that occur after mating will be essential for understanding how seasonal variation and climate change can influence fertility, reproduction, and sexual selection.

  PublisherDOI

• 74. Metastatic Vulvar Crohn's Disease in the Pediatric Population

  Journal of Pediatric and Adolescent Gynecology · 2025-02-28

  articleSenior author
  PublisherDOI

• Pediatric to Adult Transition of Care in Inflammatory Bowel Disease: Keeping Patients on Track

  Current Treatment Options in Pediatrics · 2025-11-28

  articleOpen access

  Abstract Purpose of Review Transition of care for pediatric patients with inflammatory bowel disease (IBD) is a complex, longitudinal process that requires proactive coordination between pediatric and adult gastroenterology teams. This review outlines current strategies for transition, including suggested models and validated assessment tools, as well as highlights the complexities of this process. Recent Findings Recent guidelines suggest that structured, multidisciplinary programs may improve clinical and psychosocial outcomes, although evidence is limited. Suggested models include combined clinics with both adult and pediatric providers, establishing a medical home, and the development of educational workshops. Assessment tools and resources are available for both patients and providers to assess a patient’s readiness to transition, as well as to assist in the transition process. Despite these resources, there remain ongoing gaps in the literature that include outcomes-based research and the lack of standardized metrics to define transition success. Moreover, most studies exclude patients with IBD who also have developmental delays, psychiatric co-morbidities, or other complex needs, thus widening these gaps and making this population more vulnerable to worse outcomes at the time of transition. Summary In order to improve transition and disease outcomes, providers should start the transition process early, use a multi-disciplinary approach, utilize readiness tools, involve the family or caregivers and the patient, and optimize communication between providers to transfer medical information to the new care team. Future research should prioritize quality improvement strategies and implementation science to better achieve successful transition of care for IBD patients to ensure sustained engagement in adult care.

  PublisherOA PDFDOI

• Cellular epigenetics and behavioral evolution

  Elsevier eBooks · 2025-01-01

  book-chapter1st authorCorresponding
  PublisherDOI

• Paternal response to novel predator exposure correlates with transgenerational response in offspring of threespined stickleback

  Royal Society Open Science · 2025-01-01 · 1 citations

  articleOpen accessSenior author

  Parental experiences can alter offspring phenotypes via transgenerational plasticity (TGP), which may prime offspring to adaptively respond to novel stressors, including novel predators. However, we know little about the types of sensory cues (e.g. visual, olfactory) that parents use to recognize novel predators and the consequences for offspring. Individuals may respond to novel cues if they mimic historical cues or they may need multiple sensory cues to recognize and respond to novel stimuli. We exposed threespined stickleback ( Gasterosteus aculeatus ) males to a full factorial of visual and olfactory cues of a novel trout predator prior to fertilization and tested offspring for antipredator behaviour and survival against a live predator. Fathers exposed to visual cues oriented more to and spent time closer to the novel predator post-exposure on the first day. Paternal response to visual cues was echoed in their offspring: offspring of fathers exposed to visual cues were caught faster by a live predator, suggesting that multiple cues are not needed to induce a transgenerational effect. While visual cues elicited responses both within- and transgenerationally, they do not seem to result in adaptive priming in offspring, suggesting the possibility of maladaptive TGP in response to novel cues of predation risk.

  PublisherDOI

• Integrating social learning, social networks, and non-parental transgenerational plasticity

  Trends in Ecology & Evolution · 2025-01-05 · 2 citations

  review1st authorCorresponding
  PublisherDOI

Recent grants

• Mechanisms driving multigenerational transmission of paternal stress in a new model

  NIH · $185k · 2017–2020

Frequent coauthors

• Alison M. Bell

  University of Illinois Urbana-Champaign

  23 shared

• Susan E. Marsh‐Rollo

  University of California, Santa Cruz

  19 shared

• Ian M. Hamilton

  The Ohio State University

  18 shared

• Adam R. Reddon

  Liverpool John Moores University

  17 shared

• Isaac Y. Ligocki

  Millersville University

  16 shared

• Constance M. O’Connor

  15 shared

• Sigal Balshine

  McMaster University

  13 shared

• Erika R. Carlson

  The University of Texas at Austin

  10 shared

Education

• PhD, Evolution, Ecology, and Organismal Biology

  The Ohio State University

  2016

Awards & honors

• American Council of Learned Societies (ACLS) grant
• Senior Fulbright Lectureships at the University of Antwerp (…
• Senior Fulbright Lectureships at the University of Bonn (Ger…