bluuebunny/crossref_metadata_2025_split huggingface dataset:
Demographic and spatial determinants of hybridization rate
Authors: Klein Etienne K. , Lagache‐Navarro Lélia , Petit Rémy J. 
Published: December 2016

Summary

Hybridization is a key evolutionary process with major consequences for conservation and speciation. However, sexual barriers interact with the local context to determine hybridization rates in a way that is still poorly explored. For instance, in the context of an expanding or introduced plant population, where a few individuals are isolated in populations dominated by heterospecific individuals, what is the hybridization potential?

To obtain baseline predictions on hybridization rate between two species differing in abundance and to evaluate the effect of pollen limitation, we first used a mean‐field model. We then explored a spatially explicit individual‐based mating model relying on pollen dispersal kernels to predict hybridization rates in a mixed‐species stand, under different scenarios for (i) the strength of sexual barriers; (ii) the spatial distribution of individuals within the site; (iii) the variation in individual fecundity; and (iv) the magnitude, shape and asymmetry of pollen dispersal kernels.

Pollen limitation was shown to have the potential to greatly increase hybridization rates. Similarly, fine‐scale variation in species composition can result in elevated hybridization rates compared to mean‐field predictions, especially with strong sexual barriers. However, species clustering in combination with reduced pollen dispersal has the opposite effect, protecting from hybridization.

Synthesis. Our simulation results show that variation of the pollen pool composition at the scale of individuals or stigmas due to spatial configurations or pollen limitation can substantially modify hybridization rates. We explain this by the disproportionate effect of some pollen environments on average hybridization rates. This suggests thoroughly evaluating individual behaviour in terms of hybridization, especially for rare or patchy species.
Pervasive human‐mediated large‐scale invasion: analysis of spread patterns and their underlying mechanisms in 17 of China's worst invasive plants
Authors: Horvitz Nir , Wang Rui , Wan Fang‐Hao , Nathan Ran 
Published: December 2016

Summary

Biological invasions constitute a major component of human‐induced environmental change and have become a world‐wide problem threatening global biodiversity and incurring massive economic costs. Consequently, research on biological invasions proliferates, placing a major emphasis on species traits and habitat characteristics associated with successful invasion. Yet, the mechanisms underlying rapid spread and the resulting patterns remain largely unexplored.

Using data collected since 1980 and earlier at the county level all over China, we studied the contribution of potential dispersal vectors – railroads, rail stations, roads, general human activity, rivers and winds – to the spread of 17 of China's worst invasive plant species. Focusing on long‐distance dispersal events, we calculated the minimal arrival speed for the first record of each species in each county. We also developed and applied a new method to account for observation bias due to the proximity to roads, using observational data of 776 native (non‐invasive) plant species throughout China.

We found that human‐related vectors are accountable for the vast spread of all 17 invasive plant species we examined. Spread patterns were characterized by long jumps of tens to hundreds of kilometres and extremely fast average spread rates of roughly 2–4 km per year, and a very broad range (0·1–128·2 km per year) with high variability between years. These rates are much higher than those expected from classic dispersal vectors such as water, wind or animals. Commonly used fat‐tailed dispersal kernels did not fit the observed distribution of long jumps for any species.

Synthesis. We found pervasive empirical evidence for the overriding role of humans in the large‐scale spread of invasive plants from multiple taxa. The observed spread patterns differ significantly from those portrayed in the literature, emphasizing the need to develop new frameworks to explore large‐scale spread in general and invasive spread in particular. With public data sets of invasive species observations becoming increasingly more available, the time is ripe to go beyond exploration of species traits and habitat suitability and to examine the actual patterns and the mechanisms of large‐scale invasive spread, even at a scale of thousands of kilometres over land.
Plant energetics and the synthesis of population and ecosystem ecology
Authors: Fridley Jason D. 
Published: December 2016

Summary

Historical conceptual divisions in ecology are dissolving as ecologists seek general currencies for understanding plant function, population dynamics, species interactions and ecosystem processes. Foremost among such synthetic approaches are population‐ecosystem models (PEMs), which treat the biomass dynamics of individuals as a foundation for coupled demographic and biogeochemical processes.

Because plant productivity and tissue composition drive terrestrial energy and nutrient cycling, and plant growth itself is often used as a fitness proxy, PEMs predict that phenomena related to population dynamics, such as species coexistence, are associated with processes at the ecosystem level. I argue that this line of thought reflects a persistent misunderstanding of the relationship of plant growth—the creation of new structural biomass—and individual fitness.

A survey of measured energetic costs of a wide variety of plant functions suggests that the majority of assimilated energy for many plants is allocated to survival rather than growth processes. This diversion of assimilate to survival—such as fighting infection, reducing potential tissue damage, or storing reserves in the face of defoliation risk—contributes to individual fitness but may not impact the flow of energy and nutrients in the environment or to other trophic levels.

Synthesis. Using simple models of plant energy budgets, I demonstrate how incorporating survival allocation into PEMs using a bet‐hedging approach can decouple population and ecosystem dynamics. In revisiting what little is known about how individual plants use energy, I suggest that recasting plant strategy theory in an energetic‐demographic framework may offer a useful way forward in the drive to unify population and ecosystem processes.
Servicer Contracts and the Design of Mortgage‐Backed Security Pools
Authors: Mooradian Robert M. , Pichler Pegaret 
Published: December 2016

AbstractWe develop a unified model of mortgage and servicer contracts. Renegotiating mortgage contracts following default is strictly Pareto improving, if the lender gathers updated information. An incentive compatible servicer contract requires the servicer to hold a risk position that has a value strictly greater than the cost of exerting effort. This risk position cannot in general be approximated with a horizontal “first‐loss” position. An alternative, forming a nondiversified pool, preserves pool‐wide information, avoids the cost of an incentive compatible servicer contract, and may increase MBS value.
Does temproray bilateral balloon occlusion of the common iliac arteries reduce the need for intra‐operative blood transfusion in cases of placenta accretism?
Authors: Al‐Hadethi Sinan , Fernando Shane , Hughes Simon , Thakorlal Ajay , Seruga Adam , Scurry Bonnie 
Published: December 2016

AbstractIntroductionBilateral balloon occlusion has been employed as a prophylactic measure in cases of placenta accretism prior to caesarean section with the aim of reducing blood loss and its associated morbidity/mortality. There is however no clear consensus on its efficacy in the current literature. The objective of this study was to assess the efficacy of bilateral balloon occlusion of the common iliac arteries (CIA) in reducing intra‐operative morbidity in cases of placenta accretism.MethodsThe databases of the pathology department and radiology interventional suite were reviewed over a nine year period. Fifty‐two cases of confirmed placental accretism who underwent caesarean section with or without hysterectomy were identified and divided into two groups. Twenty‐five cases had temporary occlusion of the common iliac arteries (CIA) during delivery and these were considered the study group. The reminder 27 cases did not have temporary occlusion of the CIA and were considered the control group. The two groups were compared based on gravidity, age group, post‐operative haemoglobin, drop in haemoglobin, estimated blood loss (EBL), transfusion requirement and the histopathological sub‐types of placenta accretism.ResultsThere was no statistically difference between the study and the control groups regarding EBL, post‐operative haemoglobin drop, transfusion requirement or in the placenta accretism histopathological subtype. Two cases in the study group had acute thromboembolic complications. Both groups had a single patient requiring a massive intra‐operative transfusion.ConclusionOur study was not able to detect a significant difference in blood loss or blood product requirement between patients who underwent CIA balloon in the setting of caesarean section for placenta accreta. This remains a challenging scenario requiring a multidisciplinary approach.
Neuroimaging of chronic alcohol misuse
Authors: Logan Caitriona , Asadi Hamed , Kok Hong Kuan , Looby Seamus T , Brennan Paul , O'Hare Alan , Thornton John 
Published: December 2016

SummaryAlcohol is one of the most commonly abused substances worldwide. It results in a wide range of diseases and disorders affecting many organ systems. Alcohol‐related nutritional deficiencies and electrolyte disturbance leave chronic abusers at risk of a range of demyelinating conditions to which the radiologist and clinician should always be alert. These include Wernicke's encephalopathy, Korsakoff's syndrome, Marchiafava‐Bignami disease and osmotic demyelination. Cerebral volume loss is also a commonly encountered neuroimaging phenomenon in chronic alcohol abusers. Neuroimaging with CT and MR, with a focus on FLAIR and diffusion‐weighted MR sequences, play an important role in the diagnosis and often monitoring of these conditions. We present an educational review of these entities in terms of their clinical features, neuropathology and imaging features along with a case example of each condition.
A novel method to infer the origin of polyploids from Amplified Fragment Length Polymorphism data reveals that the alpine polyploid complex of Senecio carniolicus (Asteraceae) evolved mainly via autopolyploidy
Authors: Winkler Manuela , Escobar García Pedro , Gattringer Andreas , Sonnleitner Michaela , Hülber Karl , Schönswetter Peter , Schneeweiss Gerald M. 
Published: December 2016

AbstractDespite its evolutionary and ecological relevance, the mode of polyploid origin has been notoriously difficult to be reconstructed from molecular data. Here, we present a method to identify the putative parents of polyploids and thus to infer the mode of their origin (auto‐ vs. allopolyploidy) from Amplified Fragment Length Polymorphism (AFLP) data. To this end, we use Cohen's d of distances between in silico polyploids, generated within a priori defined scenarios of origin from a priori delimited putative parental entities (e.g. taxa, genetic lineages), and natural polyploids. Simulations show that the discriminatory power of the proposed method increases mainly with increasing divergence between the lower‐ploid putative ancestors and less so with increasing delay of polyploidization relative to the time of divergence. We apply the new method to the Senecio carniolicus aggregate, distributed in the European Alps and comprising two diploid, one tetraploid and one hexaploid species. In the eastern part of its distribution, the S. carniolicus aggregate was inferred to comprise an autopolyploid series, whereas for western populations of the tetraploid species, an allopolyploid origin involving the two diploid species was the most likely scenario. Although this suggests that the tetraploid species has two independent origins, other evidence (ribotype distribution, morphology) is consistent with the hypothesis of an autopolyploid origin with subsequent introgression by the second diploid species. Altogether, identifying the best among alternative scenarios using Cohen's d can be straightforward, but particular scenarios, such as allopolyploid origin vs. autopolyploid origin with subsequent introgression, remain difficult to be distinguished.
eDNA metabarcoding: a promising method for anuran surveys in highly diverse tropical forests
Authors: Lopes Carla M. , Sasso Thais , Valentini Alice , Dejean Tony , Martins Marcio , Zamudio Kelly R. , Haddad Célio F. B. 
Published: December 2016

AbstractUnderstanding the geographical distribution and community composition of species is crucial to monitor species persistence and define effective conservation strategies. Environmental DNA (eDNA) has emerged as a powerful noninvasive tool for species detection. However, most eDNA survey methods have been developed and applied in temperate zones. We tested the feasibility of using eDNA to survey anurans in tropical streams in the Brazilian Atlantic forest and compared the results with short‐term visual and audio surveys. We detected all nine species known to inhabit our focal streams with one single visit for eDNA sampling. We found a higher proportion of sequence reads and larger number of positive PCR replicates for more common species and for those with life cycles closely associated with the streams, factors that may contribute to increased release of DNA in the water. However, less common species were also detected in eDNA samples, demonstrating the detection power of this method. Filtering larger volumes of water resulted in a higher probability of detection. Our data also show it is important to sample multiple sites along streams, particularly for detection of target species with lower population densities. For the three focal species in our study, the eDNA metabarcoding method had a greater capacity of detection per sampling event than our rapid field surveys, and thus, has the potential to circumvent some of the challenges associated with traditional approaches. Our results underscore the utility of eDNA metabarcoding as an efficient method to survey anuran species in tropical streams of the highly biodiverse Brazilian Atlantic forest.
Detecting invertebrate species in archived collections using next‐generation sequencing
Authors: Carew Melissa E. , Metzeling Leon , St Clair Rosalind , Hoffmann Ary A. 
Published: December 2016

AbstractInvertebrate biodiversity measured at mostly family level is widely used in biological monitoring programmes to assess anthropogenic impacts on ecosystems. However, next‐generation sequencing (NGS) could allow development of new more sensitive biomonitoring tools by allowing rapid species identification. This could be accelerated if archived invertebrate collections and environmental information from past programmes are used to understand species distributions and their environmental responses. In this study, we take archived macroinvertebrate samples from two sites collected on multiple occasions and test whether NGS can successfully detect species. Samples had been stored in 70% ethanol at room temperature for up to 12 years. Three amplicons ranging from 197 to 274 bps within the DNA barcode region were amplified from samples and compared to DNA barcoding libraries to identify species. We were able to amplify partial DNA barcodes from most samples, and species were often detected with multiple amplicons. However, some singletons and taxa poorly covered by DNA barcoding were missed. This suggests additional DNA barcodes will be required to fill ‘gaps’ in current DNA barcode libraries for aquatic macroinvertebrates and/or that it may not be possible to detect all taxa in a sample. Furthermore, older samples often detected fewer taxa and were less reliable for amplification, suggesting NGS is best used on samples within 8 years of collection. Nevertheless, many common taxa with existing DNA barcodes were reliably identified with NGS and were often present at sites across multiple years, showing the potential of NGS for detecting common and abundant species in archived material.
Fetal Alcohol Exposure Alters Blood Flow and Neurological Responses to Transient Cerebral Ischemia in Adult Mice
Authors: Bake Shameena , Gardner Rachel , Tingling Joseph D. , Miranda Rajesh C. , Sohrabji Farida 
Published: December 2016

BackgroundPrenatal alcohol exposure (PAE) can result in physical and neurocognitive deficits that are collectively termed “fetal alcohol spectrum disorders” (FASD). Although FASD is associated with lifelong intellectual disability, the mechanisms mediating the emergence of secondary mental health and physical disabilities are poorly understood. Based on our previous data showing that maternal ethanol (EtOH) exposure in mice resulted in an immediate reduction in cranially directed fetal blood flow, we hypothesized that such exposure would also result in persistent alterations in cranially directed blood flow in the prenatally alcohol‐exposed (PAE) adult. We also hypothesized that PAE adults exposed to an acute cerebrovascular insult would exhibit more brain damage and neurobehavioral impairment compared to non‐PAE adult controls.MethodsPregnant C57BL/6 mice were exposed to EtOH, 3 g/kg, or water by intragastric gavage. Blood flow in carotid, renal, and femoral arteries was assessed by ultrasound imaging in PAE and control adults at 3, 6, and 12 months of age. To mimic ischemic stroke in young adult populations, 3‐month‐old PAE and control animals were subject to transient middle cerebral artery occlusion (MCAo) and subsequently assessed for behavioral recovery, stroke infarct volume, and brain cytokine profiles.ResultsPAE resulted in a significant age‐related decrease in blood acceleration in adult mice, specifically in the carotid artery. A unilateral transient MCAo resulted in equivalent cortico‐striatal damage in both PAE and control adults. However, PAE adult mice exhibited significantly decreased poststroke behavioral recovery compared to controls.ConclusionsOur data collectively show that PAE adult mice exhibit a persistent, long‐term loss of cranially directed blood flow, and decreased capacity to compensate for brain trauma due to acute‐onset adult diseases like ischemic stroke.
Solar radiation increases suicide rate after adjusting for other climate factors in South Korea
Authors: Jee Hee‐Jung , Cho Chul‐Hyun , Lee Yu Jin , Choi Nari , An Hyonggin , Lee Heon‐Jeong 
Published: December 2016

ObjectivePrevious studies have indicated that suicide rates have significant seasonal variations. There is seasonal discordance between temperature and solar radiation due to the monsoon season in South Korea. We investigated the seasonality of suicide and assessed its association with climate variables in South Korea.MethodSuicide rates were obtained from the National Statistical Office of South Korea, and climatic data were obtained from the Korea Meteorological Administration for the period of 1992–2010. We conducted analyses using a generalized additive model (GAM). First, we explored the seasonality of suicide and climate variables such as mean temperature, daily temperature range, solar radiation, and relative humidity. Next, we identified confounding climate variables associated with suicide rate. To estimate the adjusted effect of solar radiation on the suicide rate, we investigated the confounding variables using a multivariable GAM.ResultsSuicide rate showed seasonality with a pattern similar to that of solar radiation. We found that the suicide rate increased 1.008 times when solar radiation increased by 1 MJ/m2 after adjusting for other confounding climate factors (P < 0.001).ConclusionSolar radiation has a significant linear relationship with suicide after adjusting for region, other climate variables, and time trends.
Childhood trauma and mixed episodes are associated with poor response to lithium in bipolar disorders
Authors: Etain B. , Lajnef M. , Brichant‐Petitjean C. , Geoffroy P. A. , Henry C. , Gard S. , Kahn J. P. , Leboyer M. , Young A. H. , Bellivier F. 
Published: December 2016

ObjectivesReliable predictors of response to lithium are still lacking in bipolar disorders (BDs). However, childhood trauma has been hypothesized to be associated with poor response to lithium.MethodsWe included 148 patients with BD, euthymic when retrospectively and clinically assessed for response to lithium and childhood trauma using reliable scales.ResultsAccording to the ‘Alda scale’, the sample consisted in 20.3% of excellent responders, 49.3% of partial responders and 30.4% of non‐responders to lithium. A higher level of physical abuse significantly correlated with a lower level of response to lithium (P = 0.009). As compared to patients not exposed to any abuse, patients with at least two trauma abuses (emotional, physical or sexual) were more at risk of belonging to the non‐responders group (OR = 4.91 95% CI (1.01–27.02)). Among investigated clinical variables, lifetime presence of mixed episodes and alcohol misuse were associated with non‐response to lithium. Multivariate analyses demonstrated that physical abuse and mixed episodes were independently associated with poor response to lithium (P = 0.005 and P = 0.013 respectively).ConclusionsChildhood physical abuse might be involved in a poor future response to lithium prophylaxis, this effect being independent of the association between clinical expression of BD and poor response to lithium.