AGA Clinical Practice Update on Telemedicine in Gastroenterology: Commentary.

DESCRIPTION: The purpose of this American Gastroenterological Association (AGA) Institute Clinical Practice Update (CPU) is to review the available evidence and provide expert advice regarding best practices for use of telemedicine in gastroenterology and hepatology. METHODS: This CPU was commissioned and approved by the AGA Institute Clinical Practice Updates Committee (CPUC) and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership and underwent internal peer review by the CPUC and external peer review through standard procedures of Gastroenterology. This expert commentary incorporates important, as well as recently published, studies in this field, and it reflects the experiences of the authors who are active gastroenterologists and hepatologists with extensive experience using telemedicine in clinical practice.

Bringing traits back into the equation: A roadmap to understand species redistribution.

Ecological and evolutionary theories have proposed that species traits should be important in mediating species responses to contemporary climate change; yet, empirical evidence has so far provided mixed evidence for the role of behavioral, life history, or ecological characteristics in facilitating or hindering species range shifts. As such, the utility of trait-based approaches to predict species redistribution under climate change has been called into question. We develop the perspective, supported by evidence, that trait variation, if used carefully can have high potential utility, but that past analyses have in many cases failed to identify an explanatory value for traits by not fully embracing the complexity of species range shifts. First, we discuss the relevant theory linking species traits to range shift processes at the leading (expansion) and trailing (contraction) edges of species distributions and highlight the need to clarify the mechanistic basis of trait-based approaches. Second, we provide a brief overview of range shift-trait studies and identify new opportunities for trait integration that consider range-specific processes and intraspecific variability. Third, we explore the circumstances under which environmental and biotic context dependencies are likely to affect our ability to identify the contribution of species traits to range shift processes. Finally, we propose that revealing the role of traits in shaping species redistribution may likely require accounting for methodological variation arising from the range shift estimation process as well as addressing existing functional, geographical, and phylogenetic biases. We provide a series of considerations for more effectively integrating traits as well as extrinsic and methodological factors into species redistribution research. Together, these analytical approaches promise stronger mechanistic and predictive understanding that can help society mitigate and adapt to the effects of climate change on biodiversity.

Local climate change velocities and evolutionary history explain multidirectional range shifts in a North American butterfly assemblage.

Species are often expected to shift their distributions either poleward or upslope to evade warming climates and colonise new suitable climatic niches. However, from 18-years of fixed transect monitoring data on 88 species of butterfly in the midwestern United States, we show that butterflies are shifting their centroids in all directions, except towards regions that are warming the fastest (southeast). Butterflies shifted their centroids at a mean rate of 4.87 km year-1. The rate of centroid shift was significantly associated with local climate change velocity (temperature by precipitation interaction), but not with mean climate change velocity throughout the species' ranges. Species tended to shift their centroids at a faster rate towards regions that are warming at slower velocities but increasing in precipitation velocity. Surprisingly, species' thermal niche breadth (range of climates butterflies experience throughout their distribution) and wingspan (often used as metric for dispersal capability) were not correlated with the rate at which species shifted their ranges. We observed high phylogenetic signal in the direction species shifted their centroids. However, we found no phylogenetic signal in the rate species shifted their centroids, suggesting less conserved processes determine the rate of range shift than the direction species shift their ranges. This research shows important signatures of multidirectional range shifts (latitudinal and longitudinal) and uniquely shows that local climate change velocities are more important in driving range shifts than the mean climate change velocity throughout a species' entire range.

Keep your cool: Overwintering physiology in response to urbanization in the acorn ant, Temnothorax curvispinosus.

Winter presents a challenge for survival, yet temperate ectotherms have remarkable physiological adaptations to cope with low-temperature conditions. Under recent climate change, rather than strictly relaxing pressure on overwintering survival, warmer winters can instead disrupt these low-temperature trait-environment associations, with negative consequences for populations. While there is increasing evidence of physiological adaptation to contemporary warming during the growing season, the effects of winter warming on physiological traits are less clear. To address this knowledge gap, we performed a common garden experiment using relatively warm-adapted versus cold-adapted populations of the acorn ant, Temnothorax curvispinosus, sampled across an urban heat island gradient, to explore the effects of winter conditions on plasticity and evolution of physiological traits. We found no evidence of evolutionary divergence in chill coma recovery nor in metabolic rate at either of two test temperatures (4 and 10 °C). Although we found the expected plastic response of increased metabolic rate under the 10 °C acute test temperature as compared with the 4 °C test temperature, this plastic response, (i.e., the acute thermal sensitivity of metabolic rate), was not different across populations. Surprisingly, we found that winter-acclimated urban ant populations exhibited higher heat tolerance compared with rural ant populations, and that the magnitude of divergence was comparable to that observed among growing-season acclimated ants. Finally, we found no evidence of differences between populations with respect to changes in colony size from the beginning to the end of the overwintering experiment. Together, these findings indicate that despite the evolution of higher heat tolerance that is often accompanied by losses in low-temperature tolerance, urban acorn ants have retained several components of low-temperature physiological performance when assessed under ecologically relevant overwintering conditions. Our study suggests the importance of measuring physiological traits under seasonally-relevant conditions to understand the causes and consequences of evolutionary responses to contemporary warming.

Microbiology and Treatment Outcomes of Community-Acquired Hematogenous Osteoarticular Infections in Infants ≤12 Months of Age.

We investigated the microbiology, management, and orthopedic outcomes of osteoarticular infections in infants age ≤1 year at our institution. Among 87 patients, Staphylococcus aureus was the most common pathogen (44.8%), followed by group B Streptococcus. Twenty-nine patients (33%), with a median age of 9.2 months, were transitioned to oral antibiotic therapy after ≤14 days of parenteral therapy; orthopedic outcomes were similar to those with prolonged parenteral therapy.

Gastrointestinal Motility and Response to Levodopa in Parkinson's Disease: A Proof-of-Concept Study.

BACKGROUND: Simultaneous measurement of gastrointestinal transit time (GITT) and plasma levodopa concentration (PLC) is crucial to understanding the effect of dysfunctional motility on levodopa response in patients with Parkinson's disease (PwPD). OBJECTIVE: The aim is to determine if altered segmental GITT correlates with clinical response and PLC variability in PwPD. METHODS: Ten typical and 10 erratic responders ingested the SmartPill (SP) wireless motility capsule. Serial PLC and finger tapping, obtained every 30 minutes for 3 hours after SP/levodopa ingestion, evaluated the correlation between GITT, clinical response, and PLC. Glucose breath testing assessed small intestinal bacterial overgrowth (SIBO). RESULTS: GITT was not significantly different in "typical" and "erratic" responders. SIBO was positive in half of the erratic and negative in most typical responders. CONCLUSION: SP is a feasible technology for assessing GITT in PwPD. A larger study may be able to significantly differentiate/correlate GITT in different segments of the GI tract with response to levodopa. © 2022 International Parkinson and Movement Disorder Society.

Physiological adaptation to cities as a proxy to forecast global-scale responses to climate change.

Cities are emerging as a new venue to overcome the challenges of obtaining data on compensatory responses to climatic warming through phenotypic plasticity and evolutionary change. In this Review, we highlight how cities can be used to explore physiological trait responses to experimental warming, and also how cities can be used as human-made space-for-time substitutions. We assessed the current literature and found evidence for significant plasticity and evolution in thermal tolerance trait responses to urban heat islands. For those studies that reported both plastic and evolved components of thermal tolerance, we found evidence that both mechanisms contributed to phenotypic shifts in thermal tolerance, rather than plastic responses precluding or limiting evolved responses. Interestingly though, for a broader range of studies, we found that the magnitude of evolved shifts in thermal tolerance was not significantly different from the magnitude of shift in those studies that only reported phenotypic results, which could be a product of evolution, plasticity, or both. Regardless, the magnitude of shifts in urban thermal tolerance phenotypes was comparable to more traditional space-for-time substitutions across latitudinal and altitudinal clines in environmental temperature. We conclude by considering how urban-derived estimates of plasticity and evolution of thermal tolerance traits can be used to improve forecasting methods, including macrophysiological models and species distribution modelling approaches. Finally, we consider areas for further exploration including sub-lethal performance traits and thermal performance curves, assessing the adaptive nature of trait shifts, and taking full advantage of the environmental thermal variation that cities generate.

A gender comparison of motivations for seeking leadership positions among gastroenterologists.

BACKGROUND AND AIMS: A gender gap exists in leadership positions in gastroenterology. However, individual motivations for seeking leadership positions within the gastroenterology community among men and women have not been explored. The primary aim of this study was to determine whether motivations for pursuing and attaining leadership positions in gastroenterology differ by gender. METHODS: A 20-question survey was created by the authors and shared with gastroenterologists electronically via a social media group (Facebook) and emails gathered through publicly available society websites and professional and social contacts. Data gathered from the survey included demographics, practice characteristics, presence of spouse or domestic partner, past and present leadership positions, motivations for pursuit of leadership positions, and reasons for lack of desire for a leadership position. RESULTS: The survey was sent to 981 gastroenterologists (679 women, 302 men). The overall response rate was 21.4% (n = 210) (20.9% for women, 22.5% for men). Overall, 41% of respondents (84 of 206) currently hold a leadership position, including more males than females (52% vs 36%, respectively; P = .03). However, among those who completed their training in the past 5 years, more women than men hold a current leadership role (25% vs 6%; P = .11). Other factors associated with currently holding a leadership position included age and years since completion of training, practice type, full-time status, and having a spouse who is not a physician. The positive factors of leadership cited most frequently were (1) ability to effect change, (2) furthering the goals of the organization, and (3) opportunity for career advancement. The negative factors cited most frequently were increased workload and decreased time for personal life. These reported positive and negative factors were similar for male and female respondents. Forty-nine respondents did not desire a leadership position now or in the future. The most common reason cited was lack of interest in the responsibilities, long hours, or stress that accompanies a leadership position (22 of 42, 52%). The second most common reason was that respondents were too busy at home or work to take on the extra responsibilities. CONCLUSIONS: A gender gap in gastroenterology leadership exists but is closing. There is fairly equal representation of men and women in leadership positions among those who completed training in the last 5 years. Many gastroenterologists are motivated for a leadership position and at the same time, many qualified individuals do not desire a leadership position because of factors that affect work-life balance. Ongoing efforts to engage motivated individuals into leadership positions and to revise the nature of leadership positions may allow for a larger talent pool from which to recruit.

Assessing the Value of Endoscopy Simulator Modules Designed to Prepare Residents for the Fundamentals of Endoscopic Surgery Examination.

BACKGROUND: The Fundamentals of Endoscopic Surgery examination is required for all general surgery residents. The test modules are not available for practice before the examination; however, similar modules are commercially available. OBJECTIVE: This study aims to determine which modules are most valuable for resident training and preparation for the examination by evaluating which correlates best with experience level. DESIGN: This was a single-institution study. SETTING: A virtual reality endoscopy simulator was utilized. PARTICIPANTS: General surgery residents and faculty endoscopists performed endoscopy simulator modules (Endobasket 2, Endobubble 1 and 2, Mucosal Evaluation 2, and Basic Navigation) designed to prepare residents for the Fundamentals of Endoscopic Surgery examination. Residents were assigned into junior and senior groups based on the completion of a dedicated endoscopy rotation. MAIN OUTCOME MEASURES: The primary outcomes measured were the mean time to completion, mean number of balloons popped, and mean number of wall hits for the 3 groups. RESULTS: A total of 21 junior residents, 11 senior residents, and 3 faculty participated. There were significant differences among groups in the mean time to completion for the Endobasket, Endobubble, and Mucosal Evaluation modules. The modules that correlated best with experience level were Endobubble 2 and Mucosal Evaluation 2. For Endobubble 2, juniors were slower than seniors, who were in turn slower than faculty (junior 118.8 ± 20.55 seconds, senior 100.3 ± 11.78 seconds, faculty 87.67 ± 2.848 seconds; p < 0.01). Juniors popped fewer balloons than seniors, who popped fewer balloons than faculty (junior 9.441 ± 3.838, senior 15.62 ± 4.133, faculty 28.78 ± 1.712; p < 0.001). For Mucosal Evaluation 2, juniors were slower than seniors, who were in turn slower than faculty (junior 468.8 ± 123.5 seconds, senior 368.6 ± 63.42 seconds, faculty 233.1 ± 70.45 seconds; p < 0.01). LIMITATIONS: Study residents have not completed the Fundamentals of Endoscopic Surgery examinations, so correlation with examination performance is not yet possible. CONCLUSIONS: Performance on Endobasket, Endobubble, and Mucosal Evaluation correlated well with experience level, providing benchmarks for each level to attain in preparation for the Fundamentals of Endoscopic Surgery examination. See Video Abstract at http://links.lww.com/DCR/A823.

Implications of the Opioid Epidemic for the Clinical Gastroenterology Practice.

PURPOSE OF REVIEW: The opioid epidemic in the USA has led to a rise in opioid-related gastrointestinal (GI) side effects that are often difficult to diagnose and treat. The aim of this report is to discuss opioid pathophysiology, opioid-related GI side effects, clinical presentation, and diagnostic criteria and to review the current pharmacotherapy available. RECENT FINDINGS: Opioid-related GI disorders are increasingly recognized and include, but are not limited to, opioid-induced esophageal dysfunction (OIED), gastroparesis, opioid-induced constipation (OIC), narcotic bowel syndrome (NBS), acute post-operative ileus, and anal sphincter dysfunction. Treatment of these conditions is challenging. OIC has the most available pharmacotherapy for treatment, including classical laxatives, peripherally acting µ-receptor antagonists (PAMORAs), novel therapies (lubiprostone, prucalopride- 5-HT agonist), and preventative therapies (PR oxycodone/naloxone). The gastrointestinal effects of opioid therapy are variable and often debilitating. While medical management for some opioid-related GI side effects exists, limiting or completely avoiding opioid use for chronic non-cancer pain will mitigate these effects most effectively.

Urban heat islands advance the timing of reproduction in a social insect.

For many species, the timing of life cycle events is advancing under contemporary global climate change. However, much less is known regarding phenological shifts as a result of other sources of anthropogenic change, such as urban warming. In both cases, progress has been hampered by a focus on phenological traits such as the timing of emergence, rather than the phenology of more directly related fitness traits such as the timing of reproduction. Here we explore how urban heat island effects shape the timing of reproduction in an acorn-dwelling ant. We used a common garden experiment with acorn ants collected from three cities in the eastern United States along a latitudinal gradient and reared long-term in the laboratory under five temperature treatments. This allowed us to quantify the effects of temperature on reproductive phenology across three scales-a biogeographic temperature cline, three urban vs. rural temperature comparisons, and five laboratory rearing temperatures. At our northernmost and southernmost cities (spanning 6° of latitude), we found both urbanization and warmer laboratory rearing temperature significantly advanced reproductive phenology; ants from the lowest latitude city also had earlier reproductive phenology compared with the higher latitude cities. In the field, the differences in urban versus rural acorn ant reproductive phenology translate to approximately one month earlier reproduction in the urban populations. For insects with synchronous mating events, such as ants, shifts in the already short window of time to reproduce could limit mating across environments, potentially leading to reproductive isolation between urban and rural populations.

Remarkable insensitivity of acorn ant morphology to temperature decouples the evolution of physiological tolerance from body size under urban heat islands.

Environmental temperature can alter body size and thermal tolerance, yet the effects of temperature rise on the size-tolerance relationship remain unclear. Terrestrial ectotherms with larger body sizes typically exhibit greater tolerance of high (and low) temperatures. However, while warming tends to increase tolerance of high temperatures through phenotypic plasticity and evolutionary change, warming tends to decrease body size through these mechanisms and thus might indirectly contribute to worse tolerance of high temperatures. These contrasting effects of warming on body size, thermal tolerance, and their relationship are increasingly important in light of global climate change. Here, we used replicated urban heat islands to explore the size-tolerance relationship in response to warming. We performed a common garden experiment with a small acorn-dwelling ant species collected from urban and rural populations across three different cities and reared under five laboratory rearing temperatures from 21 to 29 °C. We found that acorn ant body size was remarkably insensitive to laboratory rearing temperature (ant workers exhibited no phenotypic plasticity in body size across rearing temperature) and among populations experiencing cooler rural versus warmer urban environmental temperatures (no evolved differences in body size between urban and rural populations). Further, this insensitivity of body size to temperature was highly consistent across each of the three cities we examined. Because body size was robust to temperature variation, previously described plastic and evolved shifts in heat (and cold) tolerance in acorn ant responses to urbanization were shown to be independent of shifts in body size. Indeed, genetic (colony-level) correlations between heat and cold tolerance traits and body size revealed no significant association between size and tolerance. Our results show how typical trait correlations, such as between size and thermal tolerance, might be decoupled as populations respond to contemporary environmental change.

Evolution of thermal tolerance and its fitness consequences: parallel and non-parallel responses to urban heat islands across three cities.

The question of parallel evolution-what causes it, and how common it is-has long captured the interest of evolutionary biologists. Widespread urban development over the last century has driven rapid evolutionary responses on contemporary time scales, presenting a unique opportunity to test the predictability and parallelism of evolutionary change. Here we examine urban evolution in an acorn-dwelling ant species, focusing on the urban heat island signal and the ant's tolerance of these altered urban temperature regimes. Using a common-garden experimental design with acorn ant colonies collected from urban and rural populations in three cities and reared under five temperature treatments in the laboratory, we assessed plastic and evolutionary shifts in the heat and cold tolerance of F1 offspring worker ants. In two of three cities, we found evolved losses of cold tolerance, and compression of thermal tolerance breadth. Results for heat tolerance were more complex: in one city, we found evidence of simple evolved shifts in heat tolerance in urban populations, though in another, the difference in urban and rural population heat tolerance depended on laboratory rearing temperature, and only became weakly apparent at the warmest rearing temperatures. The shifts in tolerance appeared to be adaptive, as our analysis of the fitness consequences of warming revealed that while urban populations produced more sexual reproductives under warmer laboratory rearing temperatures, rural populations produced fewer. Patterns of natural selection on thermal tolerances supported our findings of fitness trade-offs and local adaptation across urban and rural acorn ant populations, as selection on thermal tolerance acted in opposite directions between the warmest and coldest rearing temperatures. Our study provides mixed support for parallel evolution of thermal tolerance under urban temperature rise, and, importantly, suggests the promising use of cities to examine parallel and non-parallel evolution on contemporary time scales.

Does Sex Influence Publication Productivity Among Colorectal Surgeons Participating in Fellowship Training Programs?

BACKGROUND: Underrepresentation of highly ranked women in academic surgery is recognized. OBJECTIVE: Our objective was to examine whether sex differences exist in faculty representation, academic rank, and publication productivity among colorectal faculty in fellowship programs. DESIGN: American Society of Colon and Rectal Surgeons fellowship program faculty were identified. Bibliometric data were obtained for each faculty member, including Hirsch index, the Hirsch index divided by research career duration, and number of publications. Linear mixed-effect regression models were constructed to determine the association between the Hirsch index and the Hirsch index divided by research career duration and sex, when controlling for institutional measures. A subset analysis of academic faculty examined the association between academic rank, sex, and Hirsch index and the Hirsch index divided by research career duration. SETTINGS: Colorectal fellowship programs, defined as academic, satellite-academic, and nonacademic, were evaluated. RESULTS: Three hundred fifty-eight faculty members were examined across 55 training programs; 22% (n = 77) were women and 78% (n = 281) were men. Sixty-one percent (n = 220) practiced in an academic setting, 23% (n = 84) in a satellite-academic setting, and 15% (n = 54) in a nonacademic setting. There was no difference in median number of publications between sexes (15 vs 10, p = 0.33); men, however, had longer careers (18 vs 11 years, p < 0.001). When controlling for confounders, there was no difference in the Hirsch index (p = 0.42) or the Hirsch index divided by research career duration (p = 0.73) between sexes. Academic rank was significantly associated with Hirsch index and the Hirsch index divided by research career duration (p < 0.001) after controlling for sex. LIMITATIONS: Our assessment of association between publication productivity and academic rank was only possible in the subset of academic faculty. In addition, this study is limited by its retrospective nature. CONCLUSIONS: We found no difference in median number of publications between men and women. When controlling for possible confounders, sex was not a significant predictor of a faculty member's publication productivity, as measured by the Hirsch index or the Hirsch index divided by research career duration; academic rank, however, was.

In Search of the Ideal Promotility Agent: Optimal Use of Currently Available Promotility Agents for Nutrition Therapy of the Critically Ill Patient.

PURPOSE OF REVIEW: Enteral nutrition therapy is essential in the management of critically ill patients. Prokinetic agents have been used successfully to aid in the delivery of nutrition and improve feeding tolerance in patients in the intensive care unit (ICU). The aim of this report is to review the existing promotility agents available for use in the critically ill as well as outline the role of potential investigative drugs in order to provide a guide to the management of this difficult and important clinical dilemma. RECENT FINDINGS: While no single currently available agent currently meets all of the desired goals in the critical care setting, there are an increasing number of available agents from which to choose including motilin receptor agonists, 5HT4 receptor agonists, D2 receptor antagonists, and Mu opioid receptor antagonists. We recommend a multifaceted approach to optimizing enteral nutrition in the critical care setting which should include the early, prophylactic use of promotility agents and should focus on the management of reversible causes of impaired gastrointestinal motility.

Intestinal Failure: New Definition and Clinical Implications.

Intestinal failure (IF) is a state in which the nutritional demands of the body are not met by the gastrointestinal absorptive surface. It is a long-recognized complication associated with short bowel syndrome, which results in malabsorption after significant resection of the intestine for many reasons or functional dysmotility. Etiologies have included Crohn's disease, vascular complications, and the effects of radiation enteritis, as well as the effects of intestinal obstruction, dysmotility, or congenital defects. While IF has been long-recognized, it has historically not been uniformly defined, which has made both recognition and management challenging. This review examines the previous definitions of IF as well as the newer definition and classification of IF and how it is essential to IF clinical guidelines.

Can Nutritional Assessment Tools Predict Response to Nutritional Therapy?

Traditional tools and scoring systems for nutritional assessment have focused solely on parameters of poor nutritional status in the past, in an effort to define the elusive concept of malnutrition. Such tools fail to account for the contribution of disease severity to overall nutritional risk. High nutritional risk, caused by either deterioration of nutritional status or greater disease severity (or a combination of both factors), puts the patient in a metabolic stress state characterized by adverse outcome and increased complications. Newer scoring systems for determining nutritional risk, such as the Nutric Score and the Nutritional Risk Score-2002 have created a paradigm shift connecting assessment and treatment with quality outcome measures of success. Clinicians now have the opportunity to identify high risk patients through their initial assessment, provide adequate or sufficient nutrition therapy, and expect improved patient outcomes as a result. These concepts are supported by observational and prospective interventional trials. Greater clinical experience and refinement in these scoring systems are needed in the future to optimize patient response to nutrition therapy.

Evolutionary change in continuous reaction norms.

Understanding the evolution of reaction norms remains a major challenge in ecology and evolution. Investigating evolutionary divergence in reaction norm shapes between populations and closely related species is one approach to providing insights. Here we use a meta-analytic approach to compare divergence in reaction norms of closely related species or populations of animals and plants across types of traits and environments. We quantified mean-standardized differences in overall trait means (Offset) and reaction norm shape (including both Slope and Curvature). These analyses revealed that differences in shape (Slope and Curvature together) were generally greater than differences in Offset. Additionally, differences in Curvature were generally greater than differences in Slope. The type of taxon contrast (species vs. population), trait, organism, and the type and novelty of environments all contributed to the best-fitting models, especially for Offset, Curvature, and the total differences (Total) between reaction norms. Congeneric species had greater differences in reaction norms than populations, and novel environmental conditions increased the differences in reaction norms between populations or species. These results show that evolutionary divergence of curvature is common and should be considered an important aspect of plasticity, together with slope. Biological details about traits and environments, including cryptic variation expressed in novel environmental conditions, may be critical to understanding how reaction norms evolve in novel and rapidly changing environments.

Evidence of plasticity, but not evolutionary divergence, in the thermal limits of a highly successful urban butterfly.

Despite the generally negative impact of urbanization on insect biodiversity, some insect species persist in urban habitats. Understanding the mechanisms underpinning the ability of insects to tolerate urban habitats is critical given the contribution of land-use change to the global insect decline. Compensatory mechanisms such as phenotypic plasticity and evolutionary change in thermal physiological traits could allow urban populations to persist under the altered thermal regimes of urban habitats. It is important to understand the contributions of plasticity and evolution to trait change along urbanization gradients as the two mechanisms operate under different constraints and timescales. Here, we examine the plastic and evolutionary responses of heat and cold tolerance (critical thermal maximum [CTmax] and critical thermal minimum [CTmin]) to warming among populations of the cabbage white butterfly, Pieris rapae, from urban and non-urban (rural) habitats using a two-temperature common garden experiment. Although we expected populations experiencing urban warming to exhibit greater CTmax and diminished CTmin through plastic and evolutionary mechanisms, our study revealed evidence only for plasticity in the expected direction of both thermal tolerance traits. We found no evidence of evolutionary divergence in either heat or cold tolerance, despite each trait showing evolutionary potential. Our results suggest that thermal tolerance plasticity contributes to urban persistence in this system. However, as the magnitude of the plastic response was low and comparable to other insect species, other compensatory mechanisms likely further underpin this species' success in urban habitats.

Physiology evolves convergently but lags behind warming in cities.

Cities, through the generation of urban heat islands, provide a venue for exploring contemporary convergent evolution to climatic warming. We quantified how repeatable the evolution of heat tolerance, cold tolerance, and body size were among diverse lineages in response to urban heat islands. Our study revealed significant shifts towards higher heat tolerance and diminished cold tolerance among urban populations. We further found that the magnitude of trait divergence was significantly and positively associated with the magnitude of the urban heat island, suggesting that temperature played a major role in the observed divergence in thermal tolerance. Despite these trends, the magnitude of trait responses lagged behind environmental warming. Heat tolerance responses exhibited a deficit of 0.84°C for every 1°C increase in warming, suggesting limits on adaptive evolution and consequent adaptational lags. Other moderators were predictive of greater divergence in heat tolerance, including lower baseline tolerance and greater divergence in body size. Although terrestrial species did not exhibit systematic shifts towards larger or smaller body size, aquatic species exhibited significant shifts towards smaller body size in urban habitats. Our study demonstrates how cities can be used to address long-standing questions in evolutionary biology regarding the repeatability of evolution. Importantly, this work also shows how cities can be used as forecasting tools by quantifying adaptational lags and by developing trait-based associations with responses to contemporary warming.