RESUMEN
OBJECTIVE: To develop and implement a resident-led firearm safety curriculum, delivered to pediatrics residents, and to evaluate outcomes. STUDY DESIGN: A firearm safety curriculum was developed in 2019-2020 at a single academic center, using Kern's framework and cognitive load theory. The curriculum was organized using the "Be SMART" firearm safety model. Sessions were led by resident peers. The content included workshops on firearm safety counseling, advocacy training, and a gun lock program in collaboration with the local police department. Content was integrated into existing residency didactic curriculum. Impact was measured by a pre/posttest knowledge assessment and a systematic chart review. RESULTS: The curriculum was provided to 41/66 (62%) pediatrics residents. Knowledge improved (67% to 77% correct) when comparing pre-intervention with post-intervention. A total of 1477 charts were reviewed. Compared with a historical cohort, participants more often asked about presence of a firearm (27% vs 69%, P < .0001) and counseled on firearm safety (9% vs 25%, P < .0001). In the post-intervention timeframe, 25% of eligible families were provided a gun lock. CONCLUSIONS: A firearm safety curriculum designed by pediatrics residents and administered to their peers resulted in a statistically significant improvement in inquiries about firearm ownership and safety counseling in an urban tertiary care continuity clinic. These results demonstrate the promising outcomes of a firearm safety program developed by residents and delivered to peers.
Asunto(s)
Armas de Fuego , Internado y Residencia , Humanos , Niño , Consejo , CurriculumRESUMEN
We previously reported that creatine supplementation improved intermittent isometric exercise performance by augmenting the total impulse performed above end-test torque (total IET'). However, our previous analyses did not enable mechanistic assessments. The objective of this study was to determine if creatine supplementation affected the IET' speed of recovery. To achieve this objective, we retrospectively analyzed our data using the IET' balance model to determine the time constant for the recovery of IET' (τIET'). Sixteen men were randomly allocated into creatine (N = 8) or placebo (N = 8) groups. Prior to supplementation, participants performed quadriceps all-out exercise to determine end-test torque (ET) and IET'. Participants then performed quadriceps exercise at ET + 10% until task-failure before supplementation (Baseline), until task-failure after supplementation (Creatine or Placebo), and until the Baseline time after supplementation (Creatine- or Placebo-Isotime). τIET' was faster than Baseline for Creatine (669 ± 98 vs 470 ± 66 s), but not Placebo (792 ± 166 vs 786 ± 161 s). The creatine-induced change in τIET' was inversely correlated with the creatine-induced changes in both the rate of peripheral fatigue development and time to task-failure. τIET' was inversely correlated with total IET' and ET in all conditions, but creatine supplementation shifted this relationship such that τIET' was faster for a given ET. Creatine supplementation, therefore, sped the recovery of IET' during intermittent isometric exercise, which was inversely related to the improvement in exercise performance. These findings support that the improvement in exercise performance after creatine supplementation was, at least in part, specific to effects on the physiological mechanisms that determine the IET' speed of recovery.HIGHLIGHTSSixteen healthy participants were randomly allocated to creatine supplementation or placebo groups.Creatine supplementation accelerated the time constant for the recovery of IET' (τIET').The time constant for the recovery of IET' (τIET') was inversely related to both the rate of peripheral fatigue development and the time to task failure.
Asunto(s)
Creatina , Suplementos Dietéticos , Masculino , Humanos , Creatina/farmacología , Torque , Estudios Retrospectivos , Fatiga , Músculo Esquelético/fisiología , Método Doble CiegoRESUMEN
BACKGROUND: The surgical management of complications after total hip arthroplasty (THA) necessitates accurate identification of the femoral implant manufacturer and model. Automated image processing using deep learning has been previously developed and internally validated; however, external validation is necessary prior to responsible application of artificial intelligence (AI)-based technologies. METHODS: We trained, validated, and externally tested a deep learning system to classify femoral-sided THA implants as one of the 8 models from 2 manufacturers derived from 2,954 original, deidentified, retrospectively collected anteroposterior plain radiographs across 3 academic referral centers and 13 surgeons. From these radiographs, 2,117 were used for training, 249 for validation, and 588 for external testing. Augmentation was applied to the training set (n = 2,117,000) to increase model robustness. Performance was evaluated by area under the receiver operating characteristic curve, sensitivity, specificity, and accuracy. Implant identification processing speed was calculated. RESULTS: The training and testing sets were drawn from statistically different populations of implants (P < .001). After 1,000 training epochs by the deep learning system, the system discriminated 8 implant models with a mean area under the receiver operating characteristic curve of 0.991, accuracy of 97.9%, sensitivity of 88.6%, and specificity of 98.9% in the external testing dataset of 588 anteroposterior radiographs. The software classified implants at a mean speed of 0.02 seconds per image. CONCLUSION: An AI-based software demonstrated excellent internal and external validation. Although continued surveillance is necessary with implant library expansion, this software represents responsible and meaningful clinical application of AI with immediate potential to globally scale and assist in preoperative planning prior to revision THA.
Asunto(s)
Artroplastia de Reemplazo de Cadera , Inteligencia Artificial , Humanos , Estudios Retrospectivos , Curva ROC , ReoperaciónRESUMEN
Abstract Introduction Neuroprogression has been proposed as the pathological rewiring of the brain that takes place in parallel with clinical and neurocognitive deterioration in the course of psychiatric disorders. This study aims to review the biological underpinnings and clinical outcomes related to neuroprogression in post-traumatic stress disorder (PTSD). Methods We performed a systematic review by searching PubMed, Embase, and Web of Science for articles published between January 1, 1960, and January 6, 2020. Inclusion criteria were met when articles assessed brain changes, neurocognition, functioning, inflammation, oxidative stress, and neurotrophins in patients with PTSD. Narrative review articles, case reports, and preclinical studies were excluded. Results A total of 965 abstracts were identified and 15 articles were included in our systematic review. It seems that for a subset of patients whose symptoms worsen or are maintained at a high intensity there is a progressive change in the frontal lobe, especially the prefrontal cortex, and worsening of both neurocognition (verbal memory and facial recognition) and functioning (physical, psychological, social and environmental). Conclusion Although current findings associate progressive reduction in frontal lobe size with neurocognitive impairment, further research is needed to characterize PTSD as a neuroprogressive disorder.
RESUMEN
NEW FINDINGS: What is the central question of this study? Do muscle size, maximal force and exercise intensity influence the recovery time constant for the finite impulse above critical torque (τIET' )? What is the main finding and its importance? Muscle size and maximal strength have different influences on the parameters of the hyperbolic torque-time to task failure relationship. Greater muscle size and maximal strength, as well as exercise at an intensity of 60% MVC, prolong τIET' during intermittent isometric exercise. ABSTRACT: Muscle perfusion and O2 delivery limitations through muscle force generation appear to play a major role in defining the hyperbolic torque-time to task failure (Tlim ) relationship. Therefore, we aimed to determine the influence of muscle size and maximal strength on the recovery time constant for the finite impulse above critical torque (τIET' ). Ten men participated in the study and performed intermittent isometric tests until task-failure (Tlim ) for the knee-extensors (KE) (35% and 60% maximal voluntary contraction (MVC)) and plantar flexors (PF) (60% MVC). The τIET' was determined for each of these Tlim tests using the IET'BAL model. The IET' (9738 ± 3080 vs. 2959 ± 1289 N m s) and end-test torque (ET)(84.5 ± 7.1 vs. 74.3 ± 12.7 N m) were significantly lower for PF compared to KE (P < 0.05). Exercise tolerance (Tlim ) was significantly longer for PF (239 ± 81 s) than KE (150 ± 55 s) at 60% MVC, and significantly longer for KE at 35% MVC (641 ± 158 s) than 60% MVC. The τIET' was significantly faster at 35% MVC (641 ± 177 s) than 60% MVC (1840 ± 354 s) for KE, both of which were significantly slower than PF at 60% MVC (317 ± 102 s). This study showed that τIET' during intermittent isometric exercise is slower with greater muscle size and maximal strength.
Asunto(s)
Contracción Isométrica , Músculo Esquelético , Electromiografía , Ejercicio Físico/fisiología , Humanos , Contracción Isométrica/fisiología , Rodilla/fisiología , Masculino , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Fuerza Muscular , Músculo Esquelético/fisiología , TorqueRESUMEN
INTRODUCTION: Neuroprogression has been proposed as the pathological rewiring of the brain that takes place in parallel with clinical and neurocognitive deterioration in the course of psychiatric disorders. This study aims to review the biological underpinnings and clinical outcomes related to neuroprogression in post-traumatic stress disorder (PTSD). METHODS: We performed a systematic review by searching PubMed, Embase, and Web of Science for articles published between January 1, 1960, and January 6, 2020. Inclusion criteria were met when articles assessed brain changes, neurocognition, functioning, inflammation, oxidative stress, and neurotrophins in patients with PTSD. Narrative review articles, case reports, and preclinical studies were excluded. RESULTS: A total of 965 abstracts were identified and 15 articles were included in our systematic review. It seems that for a subset of patients whose symptoms worsen or are maintained at a high intensity there is a progressive change in the frontal lobe, especially the prefrontal cortex, and worsening of both neurocognition (verbal memory and facial recognition) and functioning (physical, psychological, social and environmental). CONCLUSION: Although current findings associate progressive reduction in frontal lobe size with neurocognitive impairment, further research is needed to characterize PTSD as a neuroprogressive disorder.
Asunto(s)
Trastornos por Estrés Postraumático , Encéfalo/diagnóstico por imagen , HumanosRESUMEN
NEW FINDINGS: What is the central question of this study? Does creatine supplementation augment the total torque impulse accumulated above end-test torque (IET) during severe-intensity knee-extensor exercise by attenuating the rate of decrease in peak potentiated twitch torque (PT)? What is the main finding and its importance? Creatine augmented the IET and attenuated the rate of decrease in both voluntary activation and PT during severe-intensity exercise. The IET was related to the rate of decrease in PT. These findings reveal an important role for the rates of neuromuscular fatigue development as key determinants of exercise tolerance within the severe domain. ABSTRACT: This study investigated the effect of creatine supplementation on exercise tolerance, total torque impulse accumulated above end-test torque (total IET) and neuromuscular fatigue development of the knee extensors during severe-intensity intermittent isometric exercise. Sixteen men were randomly allocated into Creatine (n = 8, 20 g day-1 for 5 days) or Placebo (n = 8) groups and performed knee-extensor maximal voluntary contraction (MVC) testing, all-out testing to determine end-test torque (ET) and the finite torque impulse accumulated above end-test torque (IET'), and three submaximal tests at ET + 10%: (i) time to task failure without supplementation (Baseline); (ii) time to task failure after creatine or placebo supplementation; and (iii) time matched to Baseline after creatine (Creatine-Isotime) or placebo (Placebo-Isotime) supplementation. Creatine supplementation significantly increased the time to task failure (Baseline = 572 ± 144 s versus Creatine = 833 ± 221 s) and total IET (Baseline = 5761 ± 1710 N m s versus Creatine = 7878 ± 1903 N m s), but there were no significant differences within the Placebo group. The percentage change pre- to postexercise in MVC, voluntary activation, peak potentiated twitch torque and integrated EMG during MVC were not significantly different between Baseline and Creatine but were all significantly attenuated in Creatine-Isotime compared with Baseline. There were no significant differences in these variables within the placebo group. The total IET was significantly correlated with the rates of change in potentiated twitch torque peak (r = 0.83-0.87) and rate of torque development (r = -0.83 to -0.87) for the submaximal tests to task failure. These findings reveal an important role for the rates of neuromuscular fatigue development as key determinants of exercise tolerance during severe-intensity intermittent isometric exercise.
Asunto(s)
Creatina/administración & dosificación , Ejercicio Físico/fisiología , Contracción Isométrica/efectos de los fármacos , Fatiga Muscular/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos , Adulto , Suplementos Dietéticos , Tolerancia al Ejercicio/efectos de los fármacos , Humanos , Articulación de la Rodilla/efectos de los fármacos , Masculino , Contracción Muscular/efectos de los fármacos , TorqueRESUMEN
Urbanization can cause species to adjust their sexual displays, because the effectiveness of mating signals is influenced by environmental conditions. Despite many examples that show that mating signals in urban conditions differ from those in rural conditions, we do not know whether these differences provide a combined reproductive and survival benefit to the urban phenotype. Here we show that male túngara frogs have increased the conspicuousness of their calls, which is under strong sexual and natural selection by signal receivers, as an adaptive response to city life. The urban phenotype consequently attracts more females than the forest phenotype, while avoiding the costs that are imposed by eavesdropping bats and midges, which we show are rare in urban areas. Finally, we show in a translocation experiment that urban frogs can reduce risk of predation and parasitism when moved to the forest, but that forest frogs do not increase their sexual attractiveness when moved to the city. Our findings thus reveal that urbanization can rapidly drive adaptive signal change via changes in both natural and sexual selection pressures.
Asunto(s)
Adaptación Biológica , Comunicación Animal , Anuros/fisiología , Fenotipo , Conducta Sexual Animal , Animales , Ciudades , Masculino , Panamá , UrbanizaciónRESUMEN
Species loss from upper trophic levels can result in some major changes in community structure and ecosystem functions. Here, we experimentally excluded macroconsumers (e.g., fish and shrimp) in a Brazilian karst tropical stream during the dry season to investigate if their loss affected the accrual of calcium, dry mass (DM) and ash-free dry mass (AFDM) of sediment, benthic invertebrates, and chlorophyll-a. We found that the exclusion of macroconsumers decreased accrual of calcium. The absence of fish and shrimp may have promoted increased grazing by mayflies and snails in the electrified treatment as expressed by the depressed calcium accrual and shift in periphyton community composition. However, the exclusion of macroconsumers had no effect on DM and AFDM, chlorophyll-a, or total abundance of invertebrates. Our findings shed new light on the impact of macroconsumer loss and consequences for calcium accrual in karstic streams.
Asunto(s)
Calcio/química , Decápodos/metabolismo , Peces/metabolismo , Animales , Calcio/metabolismo , Clorofila A/análisis , Decápodos/crecimiento & desarrollo , Ecosistema , Ephemeroptera/crecimiento & desarrollo , Ephemeroptera/metabolismo , Peces/crecimiento & desarrollo , Sedimentos Geológicos/química , Estaciones del Año , Caracoles/crecimiento & desarrollo , Caracoles/metabolismoRESUMEN
PURPOSE: To evaluate a tele-education system developed to improve diagnostic competency in retinopathy of prematurity (ROP) by ophthalmologists-in-training in Mexico. DESIGN: Prospective, randomized cohort study. PARTICIPANTS: Fifty-eight ophthalmology residents and fellows from a training program in Mexico consented to participate. Twenty-nine of 58 trainees (50%) were randomized to the educational intervention (pretest, ROP tutorial, ROP educational chapters, and posttest), and 29 of 58 trainees (50%) were randomized to a control group (pretest and posttest only). METHODS: A secure web-based educational system was created using clinical cases (20 pretest, 20 posttest, and 25 training chapter-based) developed from a repository of over 2500 unique image sets of ROP. For each image set used, a reference standard ROP diagnosis was established by combining the clinical diagnosis by indirect ophthalmoscope examination and image-based diagnosis by multiple experts. Trainees were presented with image-based clinical cases of ROP during a pretest, posttest, and training chapters. MAIN OUTCOME MEASURES: The accuracy of ROP diagnosis (e.g., plus disease, zone, stage, category) was determined using sensitivity and specificity calculations from the pretest and posttest results of the educational intervention group versus control group. The unweighted kappa statistic was used to analyze the intragrader agreement for ROP diagnosis by the ophthalmologists-in-training during the pretest and posttest for both groups. RESULTS: Trainees completing the tele-education system had statistically significant improvements (P < 0.01) in the accuracy of ROP diagnosis for plus disease, zone, stage, category, and aggressive posterior ROP (AP-ROP). Compared with the control group, trainees who completed the ROP tele-education system performed better on the posttest for accurately diagnosing plus disease (67% vs. 48%; P = 0.04) and the presence of ROP (96% vs. 91%; P < 0.01). The specificity for diagnosing AP-ROP (94% vs. 78%; P < 0.01), type 2 ROP or worse (92% vs. 84%; P = 0.04), and ROP requiring treatment (89% vs. 79%; P < 0.01) was better for the trainees completing the tele-education system compared with the control group. Intragrader agreement improved for identification of plus disease, zone, stage, and category of ROP after completion of the educational intervention. CONCLUSIONS: A tele-education system for ROP education was effective in improving the diagnostic accuracy of ROP by ophthalmologists-in-training in Mexico. This system has the potential to increase competency in ROP diagnosis and management for ophthalmologists-in-training from middle-income nations.
Asunto(s)
Competencia Clínica , Educación de Postgrado en Medicina/métodos , Internet , Oftalmólogos/educación , Oftalmología/educación , Retinopatía de la Prematuridad/diagnóstico , Telemedicina/métodos , Estudios de Seguimiento , Humanos , México , Estudios Prospectivos , Reproducibilidad de los ResultadosRESUMEN
Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is an emergent infectious disease partially responsible for worldwide amphibian population declines. The spread of Bd along highland habitats (> 500 meters above sea level, m a.s.l.) of Costa Rica and Panamá is well documented and has been linked to amphibian population collapses. In contrast, data are scarce on the prevalence and dispersal of Bd in lowland habitats where amphibians may be infected but asymptomatic. Here we describe the spread (2009 to 2014) of Bd across lowland habitats east of the Panamá Canal (< 500 m a.s.l.) with a focus on the Túngara frog (Physalaemus [Engystomops] pustulosus), one of the most common and abundant frog species in this region. Highland populations in western Panamá were already infected with Bd at the start of the study, which was consistent with previous studies indicating that Bd is enzootic in this region. In central Panamá, we collected the first positive samples in 2010, and by 2014, we detected Bd from remote sites in eastern Panamá (Darién National Park). We discuss the importance of studying Bd in lowland species, which may serve as potential reservoirs and agents of dispersal of Bd to highland species that are more susceptible to chytridiomycosis.
Asunto(s)
Anuros/microbiología , Quitridiomicetos/fisiología , Micosis/veterinaria , Animales , Geografía , Micosis/epidemiología , Micosis/microbiología , Micosis/transmisión , Panamá/epidemiología , Dinámica Poblacional , PrevalenciaRESUMEN
How trees sense source-sink carbon balance remains unclear. One potential mechanism is a feedback from non-structural carbohydrates regulating photosynthesis and removing excess as waste respiration when the balance of photosynthesis against growth and metabolic activity changes. We tested this carbohydrate regulation of photosynthesis and respiration using branch girdling in four tree species in a wet tropical rainforest in Costa Rica. Because girdling severs phloem to stop carbohydrate export while leaving xylem intact to allow photosynthesis, we expected carbohydrates to accumulate in leaves to simulate a carbon imbalance. We varied girdling intensity by removing phloem in increments of one-quarter of the circumference (zero, one--quarter, half, three-quarters, full) and surrounded a target branch with fully girdled ones to create a gradient in leaf carbohydrate content. Light saturated photosynthesis rate was measured in situ, and foliar respiration rate and leaf carbohydrate content were measured after destructive harvest at the end of the treatment. Girdling intensity created no consistent or strong responses in leaf carbohydrates. Glucose and fructose slightly increased in all species by 3.4% per one-quarter girdle, total carbon content and leaf mass per area increased only in one species by 5.4 and 5.5% per one-quarter girdle, and starch did not change. Only full girdling lowered photosynthesis in three of four species by 59-69%, but the decrease in photosynthesis was unrelated to the increase in glucose and fructose content. Girdling did not affect respiration. The results suggest that leaf carbohydrate content remains relatively constant under carbon imbalance, and any changes are unlikely to regulate photosynthesis or respiration. Because girdling also stops the export of hormones and reactive oxygen species, girdling may induce physiological changes unrelated to carbohydrate accumulation and may not be an effective method to study carbohydrate feedback in leaves. In three species, removal of three-quarters of phloem area did not cause leaf carbohydrates to accumulate nor did it change photosynthesis or respiration, suggesting that phloem transport is flexible and transport rate per unit phloem can rapidly increase under an increase in carbohydrate supply relative to phloem area. Leaf carbohydrate content thus may be decoupled from whole plant carbon balance by phloem transport in some species, and carbohydrate regulation of photosynthesis and respiration may not be as common in trees as previous girdling studies suggest. Further studies in carbohydrate regulation should avoid using girdling as girdling can decrease photosynthesis through unintended means without the tested mechanisms of accumulating leaf carbohydrates.
Asunto(s)
Carbohidratos/farmacología , Fotosíntesis/efectos de los fármacos , Tallos de la Planta/crecimiento & desarrollo , Bosque Lluvioso , Árboles/fisiología , Clima Tropical , Carbono/farmacología , Respiración de la Célula/efectos de los fármacos , Respiración de la Célula/efectos de la radiación , Costa Rica , Fructosa/farmacología , Glucosa/farmacología , Luz , Modelos Biológicos , Nitrógeno/farmacología , Fotosíntesis/efectos de la radiación , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/metabolismo , Hojas de la Planta/efectos de la radiación , Tallos de la Planta/efectos de los fármacos , Tallos de la Planta/efectos de la radiación , Especificidad de la Especie , Almidón/farmacología , Árboles/efectos de los fármacos , Árboles/efectos de la radiaciónRESUMEN
Many sexual displays contain multiple components that are received through a variety of sensory modalities. Primary and secondary signal components can interact to induce novel receiver responses and become targets of sexual selection as complex signals. However, predators can also use these complex signals for prey assessment, which may limit the evolution of elaborate sexual signals. We tested whether a multimodal sexual display of the male túngara frog (Physalaemus pustulosus) increases predation risk from the fringe-lipped bat (Trachops cirrhosus) when compared with a unimodal display. We gave bats a choice to attack one of two frog models: a model with a vocal sac moving in synchrony with a mating call (multisensory cue), or a control model with the call but no vocal sac movement (unimodal cue). Bats preferred to attack the model associated with the multimodal display. Furthermore, we determined that bats perceive the vocal sac using echolocation rather than visual cues. Our data illustrate the costs associated with multimodal signaling and that sexual and natural selection pressures on the same trait are not always mediated through the same sensory modalities. These data are important when considering the role of environmental fluctuations on signal evolution as different sensory modalities will be differentially affected.
Asunto(s)
Anuros/fisiología , Percepción Auditiva , Cortejo , Ecolocación , Conducta Predatoria/fisiología , Vocalización Animal , Animales , Quirópteros/fisiología , Conducta de Elección , Masculino , Movimiento (Física) , Selección GenéticaRESUMEN
Animals have multiple senses through which they detect their surroundings and often integrate sensory information across different modalities to generate perceptions. Animal communication, likewise, often consists of signals containing stimuli processed by different senses. Stimuli with different physical forms (i.e., from different sensory modalities) travel at different speeds. As a consequence, multimodal stimuli simultaneously emitted at a source can arrive at a receiver at different times. Such differences in arrival time can provide unique information about the distance to the source. Male túngara frogs (Physalaemus pustulosus) call from ponds to attract females and to repel males. Production of the sound incidentally creates ripples on the water surface, providing a multimodal cue. We tested whether male frogs attend to distance-dependent cues created by a calling rival and whether their response depends on crossmodal comparisons. In a first experiment, we showed distance-dependent changes in vocal behavior: males responded more strongly with decreasing distance to a mimicked rival. In a second experiment, we showed that males can discriminate between relatively near and far rivals by using a combination of unimodal cues, specifically amplitude changes of sound and water waves, as well as crossmodal differences in arrival time. Our data reveal that animals can compare the arrival time of simultaneously emitted multimodal cues to obtain information on relative distance to a source. We speculate that communicative benefits from crossmodal comparison may have been an important driver of the evolution of elaborate multimodal displays.
Asunto(s)
Anuros/fisiología , Percepción de Distancia , Vocalización Animal , Animales , Percepción Auditiva , Masculino , Panamá , Vibración , AguaRESUMEN
Animals can use different sources of information when making decisions. Foraging animals often have access to both self-acquired and socially acquired information about prey. The fringe-lipped bat, Trachops cirrhosus, hunts frogs by approaching the calls that frogs produce to attract mates. We examined how the reliability of self-acquired prey cues affects social learning of novel prey cues. We trained bats to associate an artificial acoustic cue (mobile phone ringtone) with food rewards. Bats were assigned to treatments in which the trained cue was either an unreliable indicator of reward (rewarded 50% of the presentations) or a reliable indicator (rewarded 100% of the presentations), and they were exposed to a conspecific tutor foraging on a reliable (rewarded 100%) novel cue or to the novel cue with no tutor. Bats whose trained cue was unreliable and who had a tutor were significantly more likely to preferentially approach the novel cue when compared with bats whose trained cue was reliable, and to bats that had no tutor. Reliability of self-acquired prey cues therefore affects social learning of novel prey cues by frog-eating bats. Examining when animals use social information to learn about novel prey is key to understanding the social transmission of foraging innovations.
Asunto(s)
Quirópteros/fisiología , Señales (Psicología) , Aprendizaje , Conducta Predatoria , Conducta Social , Estimulación Acústica , Animales , Anuros/fisiología , Cadena Alimentaria , Masculino , Panamá , Espectrografía del SonidoRESUMEN
BACKGROUND: Uncovering how populations of a species differ genetically and ecologically is important for understanding evolutionary processes. Here we combine population genetic methods (microsatellites) with phylogenetic information (mtDNA) to define genetic population clusters of the wide-spread Neotropical túngara frog (Physalaemus pustulosus). We measure gene flow and migration within and between population clusters and compare genetic diversity between population clusters. By applying ecological niche modeling we determine whether the two most divergent genetic groups of the túngara frog (1) inhabit different habitats, and (2) are separated geographically by unsuitable habitat across a gap in the distribution. RESULTS: Most population structure is captured by dividing all sample localities into two allopatric genetic lineages. The Northern genetic lineage (NW Costa Rica) is genetically homogenous while the Southern lineage (SW Costa Rica and Panama) is sub-divided into three population clusters by both microsatellite and mtDNA analyses. Gene flow is higher within the Northern lineage than within the Southern lineage, perhaps due to increased landscape heterogeneity in the South. Niche modeling reveals differences in suitable habitat between the Northern and Southern lineages: the Northern lineage inhabits dry/pine-oak forests, while the Southern lineage is confined to tropical moist forests. Both lineages seem to have had little movement across the distribution gap, which persisted during the last glacial maximum. The lack of movement was more pronounced for the Southern lineage than for the Northern lineage. CONCLUSIONS: This study confirms the finding of previous studies that túngara frogs diverged into two allopatric genetic lineages north and south of the gap in the distribution in central Costa Rica several million years ago. The allopatric distribution is attributed to unsuitable habitat and probably other unknown ecological factors present across the distribution gap. Niche conservatism possibly contributes to preventing movements across the gap and gene flow between both groups. Genetic and ecological data indicate that there is the potential for ecological divergence in allopatry between lineages. In this context we discuss whether the Northern and Southern lineages should be recognized as separate species, and we conclude that further studies of pre- and post-zygotic isolation are needed for a final assessment. Identified population clusters should motivate future behavioral and ecological research regarding within-species biodiversity and speciation mechanisms.
Asunto(s)
Anuros/genética , Evolución Molecular , Flujo Génico , Genética de Población , Animales , Teorema de Bayes , Costa Rica , Citocromos b/genética , Ecosistema , Frecuencia de los Genes , Variación Genética , Geografía , Haplotipos , Repeticiones de Microsatélite , Modelos Biológicos , Panamá , Análisis de Secuencia de ADNRESUMEN
We measured CO(2) efflux from wood for Eucalyptus in Hawaii for 7 years and compared these measurements with those on three- and four-and-a-half-year-old Eucalyptus in Brazil. In Hawaii, CO(2) efflux from wood per unit biomass declined approximately 10x from age two to age five, twice as much as the decline in tree growth. The CO(2) efflux from wood in Brazil was 8-10x lower than that for comparable Hawaii trees with similar growth rates. Growth and maintenance respiration coefficients calculated from Hawaii wood CO(2) efflux declined with tree age and size (the growth coefficient declined from 0.4 mol C efflux mol C(-1) wood growth at age one to 0.1 mol C efflux mol C(-1) wood growth at age six; the maintenance coefficient from 0.006 to 0.001 micromol C (mol C biomass)(-1) s(-1) at 20 degrees C over the same time period). These results suggest interference with CO(2) efflux through bark that decouples CO(2) efflux from respiration. We also compared the biomass fractions and wood CO(2) efflux for the aboveground woody parts for 3- and 7-year-old trees in Hawaii to estimate how focusing measurements near the ground might bias the stand-level estimates of wood CO(2) efflux. Three-year-old Eucalyptus in Hawaii had a higher proportion of branches < 0.5 cm in diameter and a lower proportion of stem biomass than did 7-year-old trees. Biomass-specific CO(2) efflux measured at 1.4 m extrapolated to the tree could bias tree level estimates by approximately 50%, assuming no refixation from bark photosynthesis. However, the bias did not differ for the two tree sizes. Foliar respiration was identical per unit nitrogen for comparable treatments in Brazil and Hawaii (4.2 micromol C mol N(-1) s(-1) at 20 degrees C).
Asunto(s)
Dióxido de Carbono/metabolismo , Eucalyptus/metabolismo , Brasil , Hawaii , Fotosíntesis/fisiologíaRESUMEN
The vast majority of embryological research on amphibians focuses on just a single genus of frogs, Xenopus. To attain a more comprehensive understanding of amphibian development, experimentation on non-model frogs will be essential. Here, we report on the early development, rearing, and embryological analysis of túngara frogs (genus Engystomops, also called Physalaemus). The frogs Engystomops pustulosus, Engystomops coloradorum, and Engystomops randi construct floating foam-nests with small eggs. We define a table of 23 stages for the developmental period in the foam-nest. Embryos were immunostained against Lim1, neural, and somite-specific proteins and the expression pattern of RetinoBlastoma Binding Protein 6 (RBBP6) was analyzed by in situ hybridization. Due to their brief life-cycle, frogs belonging to the genus Engystomops are attractive for comparative and genetic studies of development. Developmental Dynamics 238:1444-1454, 2009. (c) 2009 Wiley-Liss, Inc.
Asunto(s)
Desarrollo Embrionario/fisiología , Ranidae/embriología , Animales , Femenino , Humanos , Hibridación in Situ , Masculino , Morfogénesis/fisiología , Ranidae/fisiología , Reproducción/fisiología , Conducta Sexual Animal/fisiologíaRESUMEN
Foliar respiration is a major component of ecosystem respiration, yet extrapolations are often uncertain in tropical forests because of indirect estimates of leaf area index (LAI). A portable tower was used to directly measure LAI and night-time foliar respiration from 52 vertical transects throughout an old-growth tropical rain forest in Costa Rica. In this study, we (1) explored the effects of structural, functional and environmental variables on foliar respiration; (2) extrapolated foliar respiration to the ecosystem; and (3) estimated ecosystem respiration. Foliar respiration temperature response was constant within plant functional group, and foliar morphology drove much of the within-canopy variability in respiration and foliar nutrients. Foliar respiration per unit ground area was 3.5 +/- 0.2 micromol CO2 m(-2) s(-1), and ecosystem respiration was 9.4 +/- 0.5 micromol CO2 m(-2) s(-1)[soil = 41%; foliage = 37%; woody = 14%; coarse woody debris (CWD) = 7%]. When modelled with El Niño Southern Oscillation (ENSO) year temperatures, foliar respiration was 9% greater than when modelled with temperatures from a normal year, which is in the range of carbon sink versus source behaviour for this forest. Our ecosystem respiration estimate from component fluxes was 33% greater than night-time net ecosystem exchange for the same forest, suggesting that studies reporting a large carbon sink for tropical rain forests based solely on eddy flux measurements may be in error.