bluuebunny/crossref_metadata_2025 huggingface dataset:
Post‐transplantation employment status of adult survivors of childhood allogeneic hematopoietic cell transplant: A report from the Center for International Blood and Marrow Transplant Research (CIBMTR)
Authors: Bhatt Neel S. , Brazauskas Ruta , Tecca Heather R. , Carreras Jeanette , Burns Linda J. , Phelan Rachel , Salit Rachel B. , Syrjala Karen L. , Talano Julie‐An M. , Shaw Bronwen E.
Published: October 2018

Background

Data are scarce regarding employment outcomes of survivors of childhood allogeneic hematopoietic cell transplantation (alloHCT) and the factors that affect their employment status.

Methods

By using the Center for International Blood and Marrow Transplant Research database, the authors studied employment outcomes of ≥1‐year survivors of childhood alloHCT who were age ≥18 years at their most recent assessment (year of transplantation, 1985‐2010). Employment status was assessed at their attained ages (ages 18‐22, 23‐27, and 28‐32 years) and according to transplantation center (TC) location (United States or International). A multivariable analysis assessing the factors that affected employed status (full‐time/part‐time work or student) was performed.

Results

Unemployment rates among 2844 survivors were persistently high at all attained ages (United States TCs: ages 18‐22 [14%], 23‐27 [15%], and 28‐32 [13%] years; International TCs: ages 18‐22 [56%], 23‐27 [53%], and 28‐32 [68%] years). The factors associated a with higher likelihood of employment included: older age at alloHCT (ages 5‐9‐years: hazard ratio [HR], 2.07; 95% confidence interval [CI], 1.65‐2.6; ages 10‐14 years: HR, 4.43; 95% CI, 3.58‐5.47; ages 15‐18‐years: HR, 7.13; 95% CI, 5.72‐8.88), myeloablative conditioning without total body irradiation (TBI) (HR, 1.56; 95% CI, 1.38‐1.77), reduced‐intensity conditioning with TBI (HR, 1.47; 95% CI, 1.19‐1.8) or without TBI (HR, 2.51; 95% CI, 2.15‐2.92), and US‐based TC (HR, 1.84; 95% CI, 1.62‐2.08).

Conclusions

Young adult survivors of childhood alloHCT have high unemployment rates at all studied attained ages after HCT. Future efforts should be directed toward understanding the causes of unemployment their and relation to quality of life using patient‐reported outcome measures.
A survey of real‐time capabilities in functional languages and compilers
Authors: Murphy Jeffrey C , Shivkumar Bhargav , Pritchard Amy , Iraci Grant , Kumar Dhruv , Kim Sun Hyoung , Ziarek Lukasz
Published: October 2018

Functional programming languages play an important role in the development of correct software systems. As embedded devices become pervasive and perform critical tasks in our lives, their reliability becomes paramount. This presents a natural opportunity to explore the application of functional programming languages to systems that demand highly predictable behavior. In this paper, we explore existing functional programming language compilers and their applicability to real‐time embedded systems. We do this by defining important characteristics needed by a real‐time programming language and survey how well existing languages meet these characteristics. We conduct empirical analysis of language runtimes in order to assess the impact of dynamic memory management on predictability and performance. Lastly, we review different programming models for expressing real‐time considerations in applications.
Are we witnessing the spectre of an HPC meltdown?
Authors: Vergara Larrea Verónica G. , Brim Michael J. , Joubert Wayne , Boehm Swen , Baker Matthew , Hernandez Oscar , Oral Sarp , Simmons James , Maxwell Don
Published: October 2018

We measure and analyze the performance observed when running applications and benchmarks before and after the Meltdown and Spectre fixes have been applied to the Cray supercomputers and supporting systems at the Oak Ridge Leadership Computing Facility (OLCF). Of particular interest is the effect of these fixes on applications selected from the OLCF portfolio when running at scale. This comprehensive study presents results from experiments run on Titan, Eos, Cumulus, and Percival supercomputers at the OLCF. The results from this study are useful for HPC users running on Cray supercomputers and serve to better understand the impact that these two vulnerabilities have on diverse HPC workloads at scale.
Cost‐minimizing online algorithm for internet green data centers on multi‐source energy
Authors: He Huaiwen , Shen Hong , Liang Dieyan
Published: October 2018

Huge energy consumption of large‐scale cloud data centers damages environments with excessive carbon emission. More and more data center operators are seeking to reduce carbon footprint via various types of renewable energy. However, the intermittent availability of renewable energy sources makes it quite challenging to cooperate with dynamically arriving workload. Meanwhile, the different natures (eg, price and carbon emission) of multiple energy sources also bring more challenges to achieve an optimal trade‐off among carbon emission, power cost, and service level agreement (SLA). In this paper, we study the problem of reducing the long‐term energy cost for geo‐distributed cloud centers, where multiple sources of renewable energy are considered and SLA requirement and carbon budget are satisfied. To tackle the randomness of workload arrival, varying electricity price, and intermittent supply of renewable energy, we first formulate the cost minimization problem as a constraint stochastic optimization problem. Second, based on Lyapunov optimization technique, we propose an online control algorithm to solve it and provide the rigorous theory analysis to demonstrate its performance. By converting the long‐term optimization problem to a mixed integer linear programming problem in each time slot, we analyze its inherent structure and propose an efficient algorithm to solve it based on Brenner's method. Our proposed algorithm makes online decisions rely only on the current system state and achieve
cost emission trade‐off. Finally, the effectiveness of our algorithm is evaluated by extensive simulations based on real‐world data traces.
Isolation and Whole‐Genome Sequencing of Environmental Campylobacter
Authors: Kelley Brittni R. , Ellis J. Christopher , Hyatt Doug , Jacobson Dan , Johnson Jeremiah
Published: October 2018

As a leading cause of bacterial‐derived gastroenteritis worldwide, Campylobacter has a significant impact on human health. In the developed world, most campylobacteriosis cases are attributed to the consumption of undercooked, contaminated poultry; however, it has been shown that Campylobacter can be transmitted to humans through contaminated water and other types of food, including beef and milk. As such, high‐resolution microbial source‐tracking is essential for health department officials to determine the source(s) of Campylobacter outbreaks. For these reasons, this protocol provides the techniques needed for isolation of Campylobacter from agricultural and environmental sources, as well as human clinical specimens. Additionally, we describe a simple method for preparing high‐quality genomic DNA that can be used for whole‐genome sequencing and downstream bioinformatics analyses of Campylobacter genotypes. © 2018 by John Wiley & Sons, Inc.
Morphogenic Regulator‐Mediated Transformation of Maize Inbred B73
Authors: Mookkan Muruganantham , Nelson‐Vasilchik Kimberly , Hague Joel , Kausch Albert , Zhang Zhanyuan J.
Published: October 2018

Maize B73 is a reference genome and has long been a major resource for genetics and molecular biology research. We have developed an efficient B73 transformation protocol by enabling somatic embryogenesis through differential co‐expression of maize morphogenic regulators BBM and WUS2. We describe a successful protocol that utilizes Agrobacterium tumefaciens strain AGL1 harboring binary vector PHP78891 that comprises a BBM and WUS2 expression cassette as well as a green fluorescent protein (GFP) reporter cassette. The PHP78891 vector also contains, within the T‐DNA region, a CRE/lox recombination system flanking the CRE/BBM/WUS2 co‐expression cassette driven by the desiccation inducible RAB17 promoter that allows removal of the BBM/WUS2 cassette. Introduction and co‐expression of BBM and WUS2 induced direct somatic embryogenesis (SE) in non‐regenerable maize B73 from immature embryo explants. Removal of the CRE/BBM/WUS2 cassette is essential to allow regeneration to fertile plants. The GFP expression cassette outside the lox excision sites is retained in the transgenic plant genome, allowing subsequent phenotypic analysis of calli and regenerated transgenic events. This transformation system enables a selectable marker‐free transformation process by taking advantage of BBM/WUS2‐induced SE as a developmental selection system. © 2018 by John Wiley & Sons, Inc.
Methoxy‐Substituted Difluoroboron Benzoylacetonate Complexes with Color‐Tunable Phosphorescence
Authors: DeRosa Christopher A. , Daly Margaret L. , Kerr Caroline , Fraser Cassandra L.
Published: October 2018

Difluoroboron β‐diketonates (BF2bdks) exhibit fluorescence (F) and room‐temperature phosphorescence (RTP) in a poly(lactic acid) (PLA) matrix. Fluorescence color tuning has been achieved by dye loading or bdk ligand modification, namely substituent effects or extended conjugation. In this study, color‐tunable RTP (450–570 nm) is achieved with 1‐benzoylacetonate derivatives by varying the number and position of methoxy groups on the benzene ring. The methoxy groups can be used to alter the energy levels of the dye or induce geometry changes (e. g. twisting) to disrupt π‐conjugation. The dyes were evaluated theoretically with density functional theory (DFT) and spectroscopy (absorbance and fluorescence) in CH2Cl2 solution and dilute PLA blends. These findings inform future boron‐based lighting devices and oxygen‐sensing bioprobe designs.
Blood‐based biopsies—clinical utility beyond circulating tumor cells
Authors: Tang Cha‐Mei , Zhu Peixuan , Li Shuhong , Makarova Olga V. , Amstutz Platte T. , Adams Daniel L.
Published: October 2018

Circulating tumor cells (CTCs), epithelial–mesenchymal transition (EMT) cells, as well as a number of circulating cancer stromal cells (CStCs) are known to shed into the blood of cancer patients. Individually, and together, these cells provide biological and clinical information about the cancers. Filtration is a method used to isolate all of these cells, while eliminating red and white blood cells from whole peripheral blood. We have previously shown that accurate identification of these cell types is paramount to proper clinical assessment by describing the overlapping phenotypes of CTCs to one such CStC, the cancer‐associated macrophage‐like cell (CAML). We report that CAMLs possess a number of parallel applications to CTCs but have a broader range of clinical utility, including cancer screening, companion diagnostics, diagnosis, prognosis, monitoring of treatment response, and detection of recurrence. © 2018 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of ISAC.
Fluorescence lifetime shifts of NAD(P)H during apoptosis measured by time‐resolved flow cytometry
Authors: Alturkistany Faisal , Nichani Kapil , Houston Kevin D. , Houston Jessica P.
Published: October 2018

Autofluorescence from the intracellular metabolite, NAD(P)H, is a biomarker that is widely used and known to reliably screen and report metabolic activity as well as metabolic fluctuations within cells. As a ubiquitous endogenous fluorophore, NAD(P)H has a unique rate of fluorescence decay that is altered when bound to coenzymes. In this work we measure the shift in the fluorescence decay, or average fluorescence lifetime (1–3 ns), of NAD(P)H and correlate this shift to changes in metabolism that cells undergo during apoptosis. Our measurements are made with a flow cytometer designed specifically for fluorescence lifetime acquisition within the ultraviolet to violet spectrum. Our methods involved culture, treatment, and preparation of cells for cytometry and microscopy measurements. The evaluation we performed included observations and quantification of the changes in endogenous emission owing to the induction of apoptosis as well as changes in the decay kinetics of the emission measured by flow cytometry. Shifts in NAD(P)H fluorescence lifetime were observed as early as 15 min post‐treatment with an apoptosis inducing agent. Results also include a phasor analysis to evaluate free to bound ratios of NAD(P)H at different time points. We defined the free to bound ratios as the ratio of ‘short‐to‐long’ (S/L) fluorescence lifetime, where S/L was found to consistently decrease with an increase in apoptosis. With a quantitative framework such as phasor analysis, the short and long lifetime components of NAD(P)H can be used to map the cycling of free and bound NAD(P)H during the early‐to‐late stages of apoptosis. The combination of lifetime screening and phasor analyses provides the first step in high throughput metabolic profiling of single cells and can be leveraged for screening and sorting for a range of applications in biomedicine. © 2018 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.
Neural correlates of delay of gratification choice in young children: Near‐infrared spectroscopy studies
Authors: Moriguchi Yusuke , Shinohara Ikuko , Yanaoka Kaichi
Published: October 2018

Delay of gratification refers to the ability to forgo a small immediate reward to obtain a larger delayed reward. Cognitive mechanisms underlying the delay of gratification in young children have been examined extensively. However, the neural mechanism of this process is largely unknown. The present study examined whether inferior prefrontal regions play an important role in the delay of gratification choice paradigm in young children. Preschool children were given a choice version of a delay of gratification task, and their neural activation during the task was assessed using near‐infrared spectroscopy in cross‐sectional (Study 1) and longitudinal designs (Study 2). Results revealed the activation of the right inferior prefrontal regions of children during the task in both studies. Specifically, the inferior prefrontal regions of the children were activated during immediate choices but not during delay choices. This study is the first to demonstrate the neural correlates of the delay of gratification in young children. We discuss how the right inferior prefrontal regions of preschool children are activated during the delay of gratification.
Eco‐evolutionary rescue promotes host–pathogen coexistence
Authors: DiRenzo Graziella V. , Zipkin Elise F. , Grant Evan H. Campbell , Royle J. Andrew , Longo Ana V. , Zamudio Kelly R. , Lips Karen R.
Published: October 2018

Emerging infectious pathogens are responsible for some of the most severe host mass mortality events in wild populations. Yet, effective pathogen control strategies are notoriously difficult to identify, in part because quantifying and forecasting pathogen spread and disease dynamics is challenging. Following an outbreak, hosts must cope with the presence of the pathogen, leading to host–pathogen coexistence or extirpation. Despite decades of research, little is known about host–pathogen coexistence post‐outbreak when low host abundances and cryptic species make these interactions difficult to study. Using a novel disease‐structured N‐mixture model, we evaluate empirical support for three host–pathogen coexistence hypotheses (source–sink, eco‐evolutionary rescue, and spatial variation in pathogen transmission) in a Neotropical amphibian community decimated byBatrachochytrium dendrobatidis(Bd) in 2004. During 2010–2014, we surveyed amphibians in Parque Nacional G. D. Omar Torríjos Herrera, Coclé Province, El Copé, Panama. We found that the primary driver of host–pathogen coexistence was eco‐evolutionary rescue, as evidenced by similar amphibian survival and recruitment rates between infected and uninfected hosts. Average apparent monthly survival rates of uninfected and infected hosts were both close to 96%, and the expected number of uninfected and infected hosts recruited (via immigration/reproduction) was less than one host per disease state per 20‐m site. The secondary driver of host–pathogen coexistence was spatial variation in pathogen transmission as we found that transmission was highest in areas of low abundance but there was no support for the source–sink hypothesis. Our results indicate that changes in the host community (i.e., through genetic or species composition) can reduce the impacts of emerging infectious disease post‐outbreak. Our disease‐structured N‐mixture model represents a valuable advancement for conservation managers trying to understand underlying host–pathogen interactions and provides new opportunities to study disease dynamics in remnant host populations decimated by virulent pathogens.
Should I shoot or should I go? Simple rules for prey selection in multi‐species hunting systems
Authors: Chang Charlotte H. , Drohan Sarah E.
Published: October 2018

Across the tropics, unregulated hunting targeting many different species presents a major conservation challenge. Prioritizing resources for monitoring and enforcement is difficult when multiple prey species are exploited. However, identifying which prey species are subject to hunting pressure can be achieved with diet choice models. We evaluate hunter diet sets using data from Southwest China and compare two diet choice models: optimal foraging theory and a relatively new diet model originating from economic optimal stopping problems. The optimal stopping diet choice model required fewer field parameters than optimal foraging models and more accurately reflected hunter catch in Southwest China. The optimal stopping model also indicated that hunters should be less selective when they experience a larger opportunity cost for their time. Finally, we illustrate a new method to evaluate harvest impact from single sites with limited data using dietary thresholds. This technique could be used to evaluate whether or not the community of exploited wildlife has shifted in its trait distribution, providing a means to anticipate trait‐biased defaunation from minimal data.
Phenotypic correlation between queen and worker brood care supports the role of maternal care in the evolution of eusociality
Authors: Walsh Justin T. , Signorotti Lisa , Linksvayer Timothy A. , d'Ettorre Patrizia
Published: October 2018

Cooperative brood care by siblings, a defining feature of eusociality, is hypothesized to be evolutionarily derived from maternal care via shifts in the timing of the expression of genes underlying maternal care. If sibling and maternal care share a genetic basis, the two behaviors are expected to be genetically and phenotypically correlated. We tested this prediction in the black garden ant Lasius niger by quantifying the brood retrieval rate of queens and their first and later generation worker offspring. Brood retrieval rate of queens was positively phenotypically correlated with the brood retrieval rate of first generation but not with later generation workers. The difference between first and later generation workers could be due to the stronger similarity in care behavior provided by queens and first generation workers compared to later generations. Furthermore, we found that queen retrieval rate was positively correlated with colony productivity, suggesting that natural selection is acting on maternal care. Overall, our results support the idea of a shared genetic basis between maternal and sibling care as well as queen and worker traits more generally, which has implications for the role of intercaste correlations in the evolution of queen and worker traits and eusociality.
Mycorrhizal interactions do not influence plant–herbivore interactions in populations of Clarkia xantiana ssp. xantiana spanning from center to margin of the geographic range
Authors: Bolin Lana G. , Benning John W. , Moeller David A.
Published: October 2018

Multispecies interactions can be important to the expression of phenotypes and in determining patterns of individual fitness in nature. Many plants engage in symbiosis with arbuscular mycorrhizal fungi (AMF), but the extent to which AMF modulate other species interactions remains poorly understood. We examined multispecies interactions among plants, AMF, and insect herbivores under drought stress using a greenhouse experiment and herbivore choice assays. The experiment included six populations of Clarkia xantiana (Onagraceae), which span a complex environmental gradient in the Southern Sierra Nevada of California. Clarkia xantiana's developing fruits are commonly attacked by grasshoppers at the end of the growing season, and the frequency of attack is more common in populations from the range center than range margin. We found that AMF negatively influenced all metrics of plant growth and reproduction across all populations, presumably because plants supplied carbon to AMF but did not benefit substantially from resources potentially supplied by the AMF. The fruits of plants infected with AMF did not differ from those without AMF in their resistance to grasshoppers. There was significant variation among populations in damage from herbivores but did not reflect the center‐to‐margin pattern of herbivory observed in the field. In sum, our results do not support the view that AMF interactions modulate plant–herbivore interactions in this system.
The impact of autotrophic versus heterotrophic nutritional pathways on colony health and wound recovery in corals
Authors: Burmester Elizabeth M. , Breef‐Pilz Adrienne , Lawrence Nicholas F. , Kaufman Les , Finnerty John R. , Rotjan Randi D.
Published: October 2018

For animals that harbor photosynthetic symbionts within their tissues, such as corals, the different relative contributions of autotrophy versus heterotrophy to organismal energetic requirements have direct impacts on fitness. This is especially true for facultatively symbiotic corals, where the balance between host‐caught and symbiont‐produced energy can be altered substantially to meet the variable demands of a shifting environment. In this study, we utilized a temperate coral–algal system (the northern star coral, Astrangia poculata, and its photosynthetic endosymbiont, Symbiodinium psygmophilum) to explore the impacts of nutritional sourcing on the host's health and ability to regenerate experimentally excised polyps. For fed and starved colonies, wound healing and total colony tissue cover were differentially impacted by heterotrophy versus autotrophy. There was an additive impact of positive nutritional and symbiotic states on a coral's ability to initiate healing, but a greater influence of symbiont state on the recovery of lost tissue at the lesion site and complete polyp regeneration. On the other hand, regardless of symbiont state, fed corals maintained a higher overall colony tissue cover, which also enabled more active host behavior (polyp extension) and endosymbiont behavior (photosynthetic ability of Symbiondinium). Overall, we determined that the impact of nutritional state and symbiotic state varied between biological functions, suggesting a diversity in energetic sourcing for each of these processes.
Trade‐off between reproductive and anti‐competitor abilities in an insect–parasitic nematode–bacteria symbiosis
Authors: Bertoloni Meli Sofia , Bashey Farrah
Published: October 2018

Mutualistic symbionts can provide diverse benefits to their hosts and often supply key trait variation for host adaptation. The bacterial symbionts of entomopathogenic nematodes play a crucial role in successful colonization of and reproduction in the insect host. Additionally, these symbionts can produce a diverse array of antimicrobial compounds to deter within‐host competitors. Natural isolates of the symbiont, Xenorhabdus bovienii, show considerable variation in their ability to target sympatric competitors via bacteriocins, which can inhibit the growth of sensitive Xenorhabdus strains. Both the bacteria and its nematode partner have been shown to benefit from bacteriocin production when within‐host competition with a sensitive competitor occurs. Despite this benefit, several isolates of Xenorhabdus do not inhibit sympatric strains. To understand how this variation in allelopathy could be maintained, we tested the hypothesis that inhibiting isolates face a reproductive cost in the absence of competition. We tested this hypothesis by examining the reproductive success of inhibiting and non‐inhibiting isolates coupled with their natural nematode host in a non‐competitive context. We found that nematodes carrying non‐inhibitors killed the insect host more rapidly and were more likely to successfully reproduce than nematodes carrying inhibitors. Lower reproductive success of inhibiting isolates was repeatable across nematode generations and across insect host species. However, no difference in insect mortality was observed between inhibiting and non‐inhibiting isolates when bacteria were injected into insects without their nematode partners. Our results indicate a trade‐off between the competitive and reproductive roles of symbionts, such that inhibiting isolates, which are better in the face of within‐host competition, pay a reproductive cost in the absence of competition. Furthermore, our results support the hypothesis that symbiont variation within populations can be maintained through context‐dependent fitness benefits conferred to their hosts. As such, our study offers novel insights into the selective forces maintaining variation within a single host–symbiont population and highlights the role of competition in mutualism evolution.
The Antarctic Circumpolar Current isolates and connects: Structured circumpolarity in the sea star Glabraster antarctica
Authors: Moore Jenna M. , Carvajal Jose I. , Rouse Greg W. , Wilson Nerida G.
Published: October 2018

Aim

The Antarctic Circumpolar Current (ACC) connects benthic populations by transporting larvae around the continent, but also isolates faunas north and south of the Antarctic Convergence. We test circumpolar panmixia and dispersal across the Antarctic Convergence barrier in the benthic sea star Glabraster antarctica.

Location

The Southern Ocean and south Atlantic Ocean, with comprehensive sampling including the Magellanic region, Scotia Arc, Antarctic Peninsula, Ross Sea, and East Antarctica.

Methods

The cytochrome c oxidase subunit I (COI) gene (n = 285) and the internal transcribed spacer region 2 (ITS2; n = 33) were sequenced. We calculated haplotype networks for each genetic marker and estimated population connectivity and the geographic distribution of genetic structure using ΦST for COI data.

Results

Glabraster antarctica is a single circum‐Antarctic species with instances of gene flow between distant locations. Despite the homogenizing potential of the ACC, population structure is high (ΦST = 0.5236), and some subpopulations are genetically isolated. Genetic breaks in the Magellanic region do not align with the Antarctic Convergence, in contrast with prior studies. Connectivity patterns in East Antarctic sites are not uniform, with some regional isolation and some surprising affinities to the distant Magellanic and Scotia Arc regions.

Main conclusions

Despite gene flow over extraordinary distances, there is strong phylogeographic structuring and genetic barriers evident between geographically proximate regions (e.g., Shag Rocks and South Georgia). Circumpolar panmixia is rejected, although some subpopulations show a circumpolar distribution. Stepping‐stone dispersal occurs within the Scotia Arc but does not appear to facilitate connectivity across the Antarctic Convergence. The patterns of genetic connectivity in Antarctica are complex and should be considered in protected area planning for Antarctica.
The disproportionate importance of long‐unburned forests and woodlands for reptiles
Authors: Dixon Kelly M. , Cary Geoffrey J. , Worboys Graeme L. , Gibbons Philip
Published: October 2018

Our understanding of the impacts of time since fire on reptiles remains limited, partly because there are relatively few locations where long‐term, spatially explicit fire histories are available. Such information is important given the large proportion of some landscapes that are managed with frequent prescribed fire to meet fuel management objectives. We conducted a space‐for‐time study across a landscape in southeastern Australia where the known fire history spanned 6 months to at least 96 years. Four methods were used to survey reptiles in 81 forest and woodland sites to investigate how time since fire (TSF), habitat, and environmental variables affect reptile richness, abundance, and composition. We used generalized linear models, generalized linear mixed‐effects models, PERMANOVA, and SIMPER to identify relationships between the reptile assemblage (richness, abundance, and composition, respectively) and TSF, habitat, and environmental variables. All three reptile metrics were associated with TSF. Reptile richness and abundance were significantly higher in sites >96 years postfire than younger fire ages (0.5–12 years). Reptile composition at long‐unburned sites was dissimilar to sites burned more recently but was similar between sites burned 0.5–2 and 6–12 years prior to sampling. Synthesis and applications. Long‐unburned forests and woodlands were disproportionately more important for reptile richness and abundance than areas burned 6 months to 12 years prior to sampling. This is important given that long‐unburned areas represent <8% of our study area. Our results therefore suggest that reptiles would benefit from protecting remaining long‐unburned areas from fire and transitioning a greater proportion of the study area to long‐unburned. However, some compositional differences between the long‐unburned sites and sites 0.5–12 years postfire indicate that maintaining a diversity in fire ages is important for conserving reptile diversity.
Chemistry of floral rewards: intra‐ and interspecific variability of nectar and pollen secondary metabolites across taxa
Authors: Palmer‐Young Evan C. , Farrell Iain W. , Adler Lynn S. , Milano Nelson J. , Egan Paul A. , Junker Robert R. , Irwin Rebecca E. , Stevenson Philip C.
Published: October 2018

Floral chemistry mediates plant interactions with pollinators, pathogens, and herbivores, with major consequences for fitness of both plants and flower visitors. The outcome of such interactions often depends on compound dose and chemical context. However, chemical diversity and intraspecific variation of nectar and pollen secondary chemistry are known for very few species, precluding general statements about their composition. We analyzed methanol extracts of flowers, nectar, and pollen from 31 cultivated and wild plant species, including multiple sites and cultivars, by liquid‐chromatography–mass‐spectrometry. To depict the chemical niche of each tissue type, we analyzed differences in nectar and pollen chemical richness, absolute and proportional concentrations, and intraspecific variability. We hypothesized that pollen would have higher concentrations and more compounds than nectar, consistent with Optimal Defense Theory and pollen's importance as a male gamete. To investigate chemical correlations across and within tissues, which could reflect physiological constraints, we quantified chemical overlap between conspecific nectar and pollen, and phenotypic integration of individual compounds within tissue types. Nectar and pollen were chemically differentiated both across and within species. Of 102 compounds identified, most occurred in only one species. Machine‐learning algorithms assigned samples to the correct species and tissue type with 98.6% accuracy. Consistent with our hypothesis, pollen had 23.8‐ to 235‐fold higher secondary chemical concentrations and 63% higher chemical richness than nectar. The most common secondary compound classes were flavonoids, alkaloids, terpenoids, and phenolics (primarily phenylpropanoids including chlorogenic acid). The most common specific compound types were quercetin and kaempferol glycosides, known to mediate biotic and abiotic effects. Pollens were distinguished from nectar by high concentrations of hydroxycinnamoyl‐spermidine conjugates, which affect plant development, abiotic stress tolerance, and herbivore resistance. Although chemistry was qualitatively consistent within species and tissue types, concentrations varied across cultivars and sites, which could influence pollination, herbivory, and disease in wild and agricultural plants. Analyses of multivariate trait space showed greater overlap across sites and cultivars in nectar than pollen chemistry; this overlap reflected greater within‐site and within‐cultivar variability of nectar. Our analyses suggest different ecological roles of nectar and pollen mediated by chemical concentration, composition, and variability.
Disturbance differentially affects alpha and beta diversity of ants in tallgrass prairies
Authors: Kim Tania N. , Bartel Savannah , Wills Bill D. , Landis Douglas A. , Gratton Claudio
Published: October 2018

Biodiversity conservation requires understanding how disturbance influences biodiversity patterns at multiple spatial scales. Because the total diversity of species within a given region (γ diversity) is influenced by both local diversity (α diversity) and dissimilarity in community composition (β diversity), understanding disturbance effects on both components of diversity is essential, especially if disturbance impacts α and β diversities differently. In this three‐year study, we examined how a disturbance (annual harvesting of grasslands) and environmental gradients in the proportion of sand locally, habitat size, and landscape diversity influenced the abundance and α and β diversities of ants within tallgrass prairie habitat in Wisconsin. We used a null‐model approach to examine how harvest and environmental factors influence β diversity. Following three years of treatments, we found that ant abundance was greater in harvested sites compared to control sites and ant abundance was positively correlated with soil sandiness. We also found that α diversity was lower in harvested sites compared to control sites and none of the measured environmental gradients influenced α diversity. The effects of harvest on α‐diversity patterns may have been mediated through the competitive interactions of the two dominant ant species (Formica montanaandLasius neoniger). In contrast, β diversity (after adjusting for random effects and changes to α diversity) was higher in harvest sites compared to control sites, and variability in community composition was largely driven by the occurrence of rare species. The proportion of sand in the local habitat and habitat size positively influenced β diversity suggesting that community dissimilarity was due in part to environmental filtering and the size of species pools. Because biomass harvest had contrasting effects on ant α and β diversities, trade‐offs in maintaining α vs. β diversity might need to be considered in land management and conservation efforts.
Low heterozygosity is associated with vector‐borne disease in crows
Authors: Townsend Andrea K. , Taff Conor C. , Wheeler Sarah S. , Weis Allison M. , Hinton Mitch G. , Jones Melissa L. , Logsdon Ryane M. , Reisen William K. , Freund David , Sehgal Ravinder N. M. , Saberi Mojan , Suh Young Ha , Hurd Jacqueline , Boyce Walter M.
Published: October 2018

Infectious diseases can have devastating impacts on wildlife populations and are of particular concern for small, inbred populations. Identifying specific pathogens that are linked to morbidity and mortality in inbred individuals is a priority for the conservation of small populations, but opportunities to examine them in the wild are rare. Here, we examined the relationship between heterozygosity and infectious disease in American crows (Corvus brachyrhynchos), a species that engages in close inbreeding, focusing on three pathogens common in Davis, California, USA: West Nile virus (WNV), Plasmodium spp. (avian malaria), and Campylobacter jejuni. We found that low heterozygosity at a panel of 33 microsatellite loci was associated with two vector‐borne infectious diseases (WNV and avian malaria), but not with infection by the bacterial gut pathogen C. jejuni. Reasons for this association with vector‐borne pathogens are unclear, but might include behavioral factors and immunological differences associated with inbreeding. Overall, these data are consistent with the idea that inbred individuals may be more susceptible to both novel and endemic vector‐borne pathogens, underscoring the importance of protecting genetic diversity within populations and buffering small populations against infectious diseases.
Phylogenetic trait conservatism predicts patterns of plant‐soil feedback
Authors: Senior John K. , Potts Brad M. , O'Reilly‐Wapstra Julianne M. , Bissett Andrew , Wooliver Rachel C. , Bailey Joseph K. , Glen Morag , Schweitzer Jennifer A.
Published: October 2018

Plant‐soil feedbacks (PSFs) are important drivers of plant community structure and diversity, with species varying in the way they both condition soils and respond to them. While plant phylogenetic relationships alone can predict this variation in some instances, trait conservatism across phylogenies may provide more reliable predictions. Using integrated common garden and glasshouse inoculation experiments including 13 Eucalyptus species across two subgenera, we specifically investigated soil microbial conditioning and root chemical traits as underlying drivers of phylogenetic differences in PSF. We found that eucalypt species responded variably to soils conditioned by closely related species, depending on their phylogenetic lineage, which was further related to root terpene concentrations and the presence/absence of specific fungal taxa in conditioned soils. Overall, these findings show that trait conservatism in root chemical traits and the subsequent conditioning of soil microbial communities can explain whether or not plants show phylogenetic patterns in PSF.
Can we detect ecosystem critical transitions and signals of changing resilience from paleo‐ecological records?
Authors: Taranu Zofia E. , Carpenter Stephen R. , Frossard Victor , Jenny Jean‐Philippe , Thomas Zoë , Vermaire Jesse C. , Perga Marie‐Elodie
Published: October 2018

Nonlinear responses to changing external pressures are increasingly studied in real‐world ecosystems. However, as many of the changes observed by ecologists extend beyond the monitoring record, the occurrence of critical transitions, where the system is pushed from one equilibrium state to another, remains difficult to detect. Paleo‐ecological records thus represent a unique opportunity to expand our temporal perspective to consider regime shifts and critical transitions, and whether such events are the exception rather than the rule. Yet, sediment core records can be affected by their own biases, such as sediment mixing or compression, with unknown consequences for the statistics commonly used to assess regime shifts, resilience, or critical transitions. To address this shortcoming, we developed a protocol to simulate paleolimnological records undergoing regime shifts or critical transitions to alternate states and tested, using both simulated and real core records, how mixing and compression affected our ability to detect past abrupt shifts. The smoothing that is built into paleolimnological data sets apparently interfered with the signal of rolling window indicators, especially autocorrelation. We thus turned to time‐varying autoregressions (online dynamic linear models, DLMs; and time‐varying autoregressive state‐space models, TVARSS) to evaluate the possibility of detecting regime shifts and critical transitions in simulated and real core records. For the real cores, we examined both varved (annually laminated sediments) and non‐varved cores, as the former have limited mixing issues. Our results show that state‐space models can be used to detect regime shifts and critical transitions in some paleolimnological data, especially when the signal‐to‐noise ratio is strong. However, if the records are noisy, the online DLM and TVARSS have limitations for detecting critical transitions in sediment records.
Associational susceptibility of a native shrub induced by context‐dependent attraction of an invasive herbivore
Authors: Lillian Sarah , Redak Richard A. , Daugherty Matthew P.
Published: October 2018

Indirect interactions among native and invasive species are notoriously difficult to predict. Here, we apply theory from trait‐mediated indirect effects and plant–insect interactions to explain the outcomes of multiple invader interactions. The present study investigates the roles of herbivore preference and plant ontogeny in mediating associational effects among a southern California native shrub, Atriplex canescens, an invasive annual forb, Brassica tournefortii, and an invasive stink bug, Bagrada hilaris. Ba. hilaris have been observed to form dense aggregations on A. canescens in late spring following senescence of Br. tournefortii, with subsequent increased mortality of A. canescens. A manipulative experiment found Ba. hilaris recruited to A. canescens in approximately 70 times greater numbers when neighbored by Br. tournefortii than when alone. Ba. hilaris nymph production, while minimized experimentally, occurred only on Br. tournefortii, suggesting A. canescens is not of sufficient quality for Ba. hilaris reproduction. In greenhouse preference trials, Ba. hilaris exhibited an overall preference for Br. tournefortii over A. canescens; however, the magnitude of preference depended on ontogenetic stage of Br. tournefortii. Overall, our results suggest significant potential for associational susceptibility mediated by a combination of Ba. hilaris preference for reproductive Br. tournefortii, substantial aggregation of Ba. hilaris onto Br. tournefortii, and a marked decline in Ba. hilaris preference for Br. tournefortii with advancing ontogeny—triggering spillover onto neighboring plants. Our results demonstrate an important role for multiple invaders and phenologically driven trait changes in mediating associational susceptibility.
Evidence for scale‐dependent topographic controls on wildfire spread
Authors: Povak Nicholas A. , Hessburg Paul F. , Salter R. Brion
Published: October 2018

Wildfire ecosystems are thought to be self‐regulated through pattern–process interactions between ignition frequency and location, and patterns of burned and recovering vegetation. Yet, recent increases in the frequency of large wildfires call into question the application of self‐organization theory to landscape resilience. Topography represents a stable bottom‐up template upon which fire interacts as both a physical and an ecological process. However, it is unclear how topographic control changes geographically and across spatial scales. We analyzed fire perimeter and topography data from 16 Bailey ecoregions across the State of California to identify spatial correspondence between ecoregional fire event and topographic patch size distributions. We found both sets of distributions followed a power‐law form and were statistically similar across several orders of magnitude, for most ecoregions. As a direct test of topographic controls on fire event perimeters, we used a paired t‐test across ~11,000 fires to identify differences in topographic attributes at fire boundaries versus fire interiors. Statistical significance was determined using 500 iterations of a neutral landscape model. Level of topographic control varied significantly by ecoregion and across topographic features. For example, north–south aspect breaks, valley bottoms, and roads showed a consistently high degree of spatial control on wildfire perimeters. Topographic controls were most pronounced in mountainous ecoregions and were least influential in arid regions. Ridgetops provided a low‐level control across all ecoregions. Spatial control was strongest for small (100–102 ha) to medium (103–104 ha) fire sizes, suggesting that controls were scale‐dependent rather than scale‐invariant. Roads were the dominant control across all ecoregions; however, removing roads from the analyses had no significant effect on the overall role of topography on wildfire extinguishment in this analysis. This result suggested that certain topographic settings show strong spatial control on fire growth, despite the presence of roads. Our results support the observation that both bottom‐up and top‐down factors constrain fire sizes and that there are likely scaling regions within fire size distributions wherein the dominance of these spatial controls varies. Human influences on fire spread may either diminish or enhance the role of some bottom‐up and top‐down factors, adding further complexity.
Loss of biodiversity alters ecosystem function in freshwater streams: potential evidence from benthic macroinvertebrates
Authors: Cao Xiaofeng , Chai Liwei , Jiang Dalin , Wang Jie , Liu Yanqiu , Huang Yi
Published: October 2018

Particular attention has been paid on the evidence that ecosystem function can be impacted by changes of biodiversity. However, how the loss of biodiversity alters the ecosystem function in aquatic ecosystems remains unclear. Here, the effects of benthic macroinvertebrate community structure on ecosystem function and the possibility of which being shifted by ecological threshold along the habitat condition gradient were examined by quantifying community structure and ecosystem function in streams of Lake Dianchi basin. The results demonstrated that the relative abundance of Oligochaete was significantly linear correlated with ecosystem multifunctions, especially N and P cycling functions, as well as the dominant taxon% and Gather‐Collectors% closely affected P cycling function and multifunctions, respectively, while no remarkable nonlinearities were observed. Besides, there was a distinct shift from sensitive taxa‐dominated healthy state to tolerant taxa‐dominated degraded state with an increase in habitat pressure. The nonlinear transition of benthic macroinvertebrate community structure in combination with altered ecosystem function clearly indicated the present of extinction threshold in the process of stream habitat degradation. The findings contribute to the growing evidence for fully understanding the implications of biodiversity loss in ecosystem function.
Release of hatchery adult steelhead for angler opportunity increases potential for interactions with endemic steelhead
Authors: Erdman Charles S. , Caudill Christopher C. , Naughton George P. , Jepson Michael A.
Published: October 2018

Translocation is often used to increase local abundance of fish and wildlife populations for conservation or harvest purposes, and effects of releases on recipient populations are context dependent. Release of non‐local animals intended for harvest can have negative demographic, genetic, and ecological risks to endemic populations when not harvested. In 2012–2014, we used radiotelemetry to monitor the fate and potential for interactions between non‐local hatchery‐origin adult summer‐run steelhead Oncorhynchus mykiss (n = 423) and Endangered Species Act (ESA)‐listed native winter‐run steelhead (WRS) in two tributaries of the Willamette River, Oregon, USA. Summer steelhead were recycled—collected, translocated downstream, and released—to provide additional angler opportunity as a part of a regional mitigation program. Overall, reported harvest rate of recycled steelhead was low (15%) and a majority of individuals (62%) were last recorded in the release tributary. Furthermore, 14% of radio‐tagged recycled steelhead were last detected outside the release tributary (i.e., strayed after release). Expanded estimates indicate the number of recycled summer‐run steelhead remaining in the South Santiam River exceeded the WRS spawning population size. Low reported harvest and straying and demographic estimates indicate the recycling program may have negative effects on endemic WRS. Translocation and hatchery supplementation are likely to remain important conservation and mitigation tools in the future, though these results highlight the importance of post‐release monitoring and considering both the risks and benefits of translocations to endemic populations and communities.