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Power-law relationships are among the most well-studied functional relationships in biology. Recently the common practice of fitting power laws using linear regression (LR) on log-transformed data has been criticized, calling into question the conclusions of hundreds of studies. It has been suggested that nonlinear regression (NLR) is preferable, but no rigorous comparison of these two methods has been conducted. Using Monte Carlo simulations, we demonstrate that the error distribution determines which method performs better, with NLR better characterizing data with additive, homoscedastic, normal error and LR better characterizing data with multiplicative, heteroscedastic, lognormal error. Analysis of 471 biological power laws shows that both forms of error occur in nature. While previous analyses based on log-transformation appear to be generally valid, future analyses should choose methods based on a combination of biological plausibility and analysis of the error distribution. We provide detailed guidelines and associated computer code for doing so, including a model averaging approach for cases where the error structure is uncertain.

BACKGROUND:The incidence of spina bifida (SB) in the developing world is higher than in the United States because of malnutrition and folic acid deficiency during pregnancy. Advances in technology have made prenatal repair of myelomeningocele (MM) possible. OBJECTIVE:The objective of the guidelines are, (1) To create clinical recommendations for best practices, based on a systematic review and analysis of available literature, (2) to obtain multi-disciplinary endorsement of these guidelines from relevant organizations, and (3) to disseminate the educational content to physicians to improve the care of infants with MM. METHODS:The Guidelines Task Force developed search terms and strategies used to search PubMed and Embase for literature published between 1966 and September 2016. Strict inclusion/exclusion criteria were used to screen abstracts and to develop a list of relevant articles for full-text review. RESULTS:Guidelines authors aimed to systematically review the literature and make evidence based recommendations about the timing of closure after birth, hydrocephalus, the impact of prenatal closure, and the effect of prenatal closure on ambulation ability and tethered spinal cord. Evidence concerning persistent ventriculomegaly and cognitive impairment was also evaluated. Hundreds of abstracts were identified and reviewed for each of the 5 topics. A total of 14 studies met stringent inclusion criteria. CONCLUSION:Based on a comprehensive systematic review, a total of 5 clinical practice recommendations were developed, with 1 Level I, 2 Level II and 2 Level III recommendations.The full guideline can be found at https://www.cns.org/guidelines/guidelines-spina-bifida-chapter-1.

We used several pollination treatments and irregular collections of flower visitors to determine the breeding systems and likely pollinators of 2 rare species of Sclerocactus of the Colorado Plateau listed under the U.S. Endangered Species Act. We found one species, S. wrightiae, to be self-incompatible, and the other, S. mesae-verdae, to be partially self-compatible in the populations studied. Neither species was capable of setting fruits without the services of pollinators. The flower visitors and most likely pollinators of both species were various species of ground-nesting sweat bees (Halictidae). Management plans to conserve rare plant species must include support for studies to determine the nesting habitat and flight ranges of their pollinators so that their populations may also be protected. Utilizamos varios tratamientos de polinización y recolectas irregulares de visitantes florales para determinar los sistemas de reproducción y los posibles polinizadores de dos especies raras de Sclerocactus de la Meseta de Colorado incluidas en la Ley de Especies en Peligro de Extinción de los EE. UU. En las poblaciones estudiadas, encontramos una especie auto-incompatible (S. wrightiae), y otra parcialmente auto-compatible (S. mesae-verdae). Ninguna de las especies fue capaz de producir frutos sin los servicios de los polinizadores. Los visitantes florales y los polinizadores potenciales de ambas especies fueron varias especies de abejas sudoríparas que anidan en el suelo (Halictidae). Los planes de gestión para conservar especies de plantas raras deben incluir estudios para determinar el hábitat de anidación y rangos de vuelo de sus polinizadores para que estas poblaciones también puedan ser protegidas.

Twenty-five years ago, Arctomecon humilis, a pollinator-dependent, endangered poppy globally restricted to the extreme northeastern Mojave Desert in southwestern Utah, was pollinated by native bee species and the European honey bee. Follow-up studies beginning in 2012 failed to find the two most important native bee pollinator species, one of which, Perdita meconis, is a strict poppy specialist. We had four objectives: (1) confirm the status of formerly important native bee pollinators; (2) determine the role of the Africanized honey bee which reportedly invaded southern Utah in 2008; (3) examine the effect of the ostensible change in pollinator fauna on fruit set in four populations; (4) describe the pollination proficiency of species that presently visit poppy flowers. For the fourth consecutive survey, P. meconis was absent; its local extinction in Utah now seems certain. Another previously important native pollinator, Eucera quadricincta, was very rare. Also uncommon was the European honey bee, having been largely replaced by Africanized honey bees which have become, in most populations, the prevalent pollinator. Africanized bees forage early in the day and quickly strip flowers of their copious pollen leaving little for native bees. We argue that the invasion of southern Utah by Africanized bees is the most likely cause of the severe disruption of the A. humilis pollination system. The ascension of the Africanized bee is also associated with reduced fruit set in all poppy populations, especially those where plants are sparse. Arctomecon humilis now appears to depend mostly on an invasive species for pollination.

Classic theories suggest that common pool resources are subject to overexploitation. Community-based resource management approaches may ameliorate tragedy of the commons effects. Here we use a randomized evaluation in Namibia’s communal rangelands to study a comprehensive four-year program to support community-based rangeland and cattle management. We find that the program led to persistent and large improvements for eight of thirteen indices of social and behavioral outcomes. Effects on rangeland health, cattle productivity and household economics, however, were either negative or nil. Positive impacts on community resource management may have been offset by communities’ inability to control grazing by non-participating herds and inhibited by an unresponsive rangeland sub-system. This juxtaposition, in which measurable improvements in community resource management did not translate into better outcomes for households or rangeland health, demonstrates the fragility of the causal pathway from program implementation to intended socioeconomic and environmental outcomes. It also points to challenges for improving climate change–adaptation strategies.

BackgroundPrevious research has identified numerous factors to explain why students have difficulty learning about evolution. Some of these factors include a student’s background (including their religion and major of study), the type of evolution instruction, and the inclusion of the nature of science (NOS) instruction. Sparse but more recent work has investigated the impact of a religious-scientist role model to help dampen perceptions of conflict between evolutionary science and worldview. We had two research goals: (1) to identify which of these factors influence students’ learning of evolution in post-secondary education; and (2) to describe the relationships among incoming biology students’ creationist reasoning, knowledge of evolution, and perceived conflict between evolution and their worldview.ResultsThe single factor linked with the reduction in both creationist reasoning and in students’ perceived conflict between evolution and their worldview through a semester was the presence of a role model. Likewise, knowledge and perceived relevance of evolution increased in sections with a role model instructor and with evidence-based evolution instruction. Otherwise, tested factors (the type of evolution instruction, inclusion of NOS, biology-major/nonmajor, GPA, or religiosity) were not shown to be associated with these three constructs. We found that in the first week of the semester students with higher knowledge of evolution had lower creationist reasoning and lower perceived conflict.ConclusionsThe single factor that collectively reduced erroneous beliefs, increased scientific knowledge, and minimized perceived conflict was the presence of a religious-scientist role model. Previous work has suggested a role model could positively impact students’ learning of evolution, yet this is the first quasi-experimental evidence supporting the importance of the course instructor as the role model in students’ learning of evolution. These findings are especially relevant to institutions with a greater proportion of religious students who could benefit from modeling to help foster their learning of evolution.

BACKGROUND:Myelomeningocele (MM) is a condition that is responsible for considerable morbidity in the pediatric population. A significant proportion of the morbidity related to MM is attributable to hydrocephalus and the surgical management thereof. Postnatal repair remains the most common form of treatment; however, increased rates of prenatal diagnosis, advances in fetal surgery, and a hypothesis that neural injury continues in utero until the MM defect is repaired have led to the development and evaluation of prenatal surgery as a means to improve outcomes in afflicted infants. OBJECTIVE:The objective of this guideline is to systematically evaluate the literature to determine whether there is a difference in the proportion of patients who develop shunt-dependent hydrocephalus in infants who underwent prenatal MM repair compared to infants who had postnatal repair. METHODS:The Guidelines Task Force developed search terms and strategies used to search PubMed and Embase for relevant literature published between 1966 and September 2016. Strict inclusion/exclusion criteria were used to screen abstracts and to develop a list of relevant articles for full-text review. Full-text articles were then reviewed, and when appropriate, included as evidence. RESULTS:A total of 87 abstracts were identified and reviewed by 3 independent reviewers. Thirty-nine full-text articles were selected for analysis. Three studies met selection criteria and were included in the evidence table. CONCLUSION:Class I evidence from 1 study and class III evidence from 2 studies suggest that, in comparison to postnatal repair, prenatal surgery for MM reduces the risk of developing shunt-dependent hydrocephalus. Therefore, prenatal repair of MM is recommended for those fetuses who meet specific criteria for prenatal surgery to reduce the risk of developing shunt-dependent hydrocephalus (level I). Differences between prenatal and postnatal repair with respect to the requirement for permanent cerebrospinal fluid diversion should be considered alongside other relevant maternal and fetal factors when deciding upon a preferred method of MM closure.The full guideline can be found at https://www.cns.org/guidelines/guidelines-spina-bifida-chapter-2.

Summary Glucocorticoids are important mediators of energy utilization for key physiological processes, including immune function. Much work has focused on the effects of energy limitation and stress for key physiological processes such as reproduction and immunity. However, it is unclear how stress alters energy use across different energy states, and the physiological ramifications of such effects are even less clear. In this study, we altered energy and stress states of an infrequent feeder, the terrestrial gartersnake (Thamnophis elegans), using fasting and repeated restraint stress (chronic stressors) to test how these challenges interacted to affect immune function, energy metabolites and glucocorticoid reactivity (a traditional indicator of stress state) to restraint stress, a standardized, acute stressor. After this acute stressor, the snakes which had received chronic stress had increased glucocorticoid reactivity, and both treatments altered energy metabolite use and storage. Evidence of interaction of food restriction and chronic stress treatments on innate immune function and energy metabolites (triglycerides and glycerol) suggests that stress alters energy use in a manner dependent on the energy state of the animal. Snakes have a remarkable ability to maintain functionality of key physiological processes under stressful conditions but are still susceptible to multiple simultaneous stressors, a situation increasingly prevalent in our ever‐changing environment. Lay Summary

BACKGROUND:The incidence of spina bifida (SB) is higher in the developing world as compared to the United States because of folic acid deficiency during pregnancy. Advances in technology have made prenatal repair of myelomeningocele (MM) possible. OBJECTIVE:The objective of this guideline was to determine if there is a difference in the rate of development of tethered cord syndrome (TCS) in infants who had prenatal closure compared to infants who had MM repair after birth. METHODS:The Guidelines Task Force developed search terms and strategies to search PubMed and Embase for the relevant literature published between 1966 and September 2016. Strict inclusion/exclusion criteria were used. Full text articles were reviewed and, when appropriate, included as evidence. RESULTS:A total of 261 abstracts were reviewed. Fifty-four full-text articles were selected for further analysis. Three studies met inclusion criteria. CONCLUSION:There was Class II evidence from 1 study and Class III evidence from another 2 studies demonstrating that TCS develops in infants with prenatal MM closure at an equal or higher rate than with postnatal closure. There was an increased risk of development of inclusion cysts in infants who underwent in utero closure. Continued surveillance for TCS and/or the development of inclusion cysts in children with prenatal and postnatal closure of MM is indicated (Level II). Differences between prenatal and postnatal repair with respect to the development of TCS and/or inclusion cysts should be considered alongside other relevant maternal and fetal outcomes when deciding upon a preferred method for MM closure.The full guideline can be found at https://www.cns.org/guidelines/guidelines-spina-bifida-chapter-6.

BACKGROUND:Appropriate timing for closure of myelomeningocele (MM) varies in the literature. Older studies present 48 h as the timeframe after which infection complication rates rise. OBJECTIVE:The objective of this guideline is to determine if closing the MM within 48 h decreases the risk of wound infection or ventriculitis. METHODS:The Guidelines Task Force developed search terms and strategies used to search PubMed and Embase for relevant literature published between 1966 and September 2016. Strict inclusion/exclusion criteria were used to screen abstracts and to develop a list of relevant articles for full-text review. Full text articles were then reviewed and when appropriate, included in the evidentiary table. The class of evidence was evaluated, discussed, and assigned to each study that met inclusion criteria. RESULTS:A total of 148 abstracts were identified and reviewed. A total of 31 articles were selected for full text analysis. Only 4 of these studies met inclusion criteria. CONCLUSION::There is insufficient evidence that operating within 48 h decreases risk of wound infection or ventriculitis in 1 Class III study. There is 1 Class III study that provides evidence of global increase in postoperative infection after 48 h, but is not specific to wound infection or ventriculitis. There is 1 Class III study that provides evidence if surgery is going to be delayed greater than 48 h, antibiotics should be given.The full guideline can be found at https://www.cns.org/guidelines/guidelines-spina-bifida-chapter-4.