scholarly journals River dynamics and invasion: distribution patterns of native and invasive woody vegetation at the Río Negro, Argentina

2015 ◽  
Vol 2 (1) ◽  
pp. 45-57 ◽  
Author(s):  
Lisa K. Thomas ◽  
Eva Mosner ◽  
Ilona Leyer
Keyword(s):  
Niche Overlap ◽  
Ecological Niches ◽  
Life Stages ◽  
Riparian Ecosystems ◽  
Distribution Models ◽  
Potential Threat ◽  
Randomized Sampling ◽  
Rio Negro ◽  
Invasive Taxa ◽  
The Impact

AbstractSalicaceae are typical invaders of riparian ecosystems throughout the world and they have the potential to change much of the invaded habitats. Along Patagonian streams, riparian softwood forests composed of non-native Salicaceae are increasing in abundance, area and tree species diversity. Especially in the last decades, dense floodplain forests dominated by invasive willows and poplars and additionally Russian olive and tamarisk spread almost explosively e.g. along the Río Negro in northern Patagonia. This study focuses on the identification of ecological niches and niche overlaps of the native and invasive woody species in order to assess the impact on the native Salix humboldtiana Willd. Data on species (presence/ absence) and explanatory variables were gathered in the field using a grid-based, stratified-randomized sampling design. Different environmental variables were then related to species occurrence in different life stages (adult, juvenile, seedling) using habitat distribution models. In the final models, flood duration, the amount of gravel and the location (upper or middle river valley) were included to describe the probability of occurrence of native and invasive taxa. For all life stages, a strong niche overlap could be observed for S. humboldtiana and the invasive taxa with no remaining exclusive habitats indicating a potential threat to the native willow. The study contributes to a better understanding of Salicaceae invasion and its consequences for riparian ecosystems.

scholarly journals Ecological niche overlap among species of the genus Zaluzania (Asteraceae) from the dry regions of Mexico

2020 ◽  
Vol 153 (3) ◽  
pp. 337-347
Author(s):  
Mario Ernesto Suárez-Mota ◽  
José Luis Villaseñor
Keyword(s):  
Ecological Niche ◽  
Potential Distribution ◽  
Area Under The Curve ◽  
Niche Overlap ◽  
Ecological Niches ◽  
Niche Conservatism ◽  
Distribution Models ◽  
Closely Related Species ◽  
Environmental Pressures ◽  
Fundamental Niche

Background and aims – The hypothesis of ecological niche conservatism postulates that closely related species share ecologically similar environments; that is, they tend to maintain the characteristics of their fundamental niche over time. The objective of this study is to evaluate the similarity and equivalence of the ecological niches among species of the genus Zaluzania (Asteraceae), characteristic of the Mexican arid and semi-arid regions, to infer their potential niche conservatism. Methods – Based on critically reviewed herbarium occurrence data, potential distribution models for eight species of Zaluzania were generated using the Maxent algorithm. The overlap between potential distribution areas was then evaluated using equivalence and ecological niche parameters implemented in the ENMTools software; for this we quantified the degree of overlap and similarity between the niches using the equivalence (D) and similarity (I) parameters.Key results – The resulting models show that species display areas of high suitability along the Mexican dry regions, as well as overlapping heterogeneous values. All models showed high AUC (Area Under the Curve) values (> 0.8). The D and I values between each pair of species showed low values of overlap.Conclusions – Each species of the genus shows a fundamental niche distinct from their sister species. The genus thus offers an example of niche divergence among species, with each one adapting to different environmental pressures. Our results do not support the hypothesis of niche conservatism in the genus, suggesting that the species evolved in divergent environments.

scholarly journals Ecological niche differentiation in Chiroxiphia and Antilophia manakins (Aves: Pipridae)

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0243760
Author(s):  
Mariana Villegas ◽  
Bette A. Loiselle ◽  
Rebecca T. Kimball ◽  
John G. Blake
Keyword(s):  
Ecological Niche ◽  
Niche Overlap ◽  
Niche Differentiation ◽  
Ecological Niches ◽  
Niche Conservatism ◽  
Phylogenetic Distance ◽  
Evolutionary Time ◽  
Distribution Models ◽  
Ecological Differentiation ◽  
Niche Divergence

Species distribution models are useful for identifying the ecological characteristics that may limit a species’ geographic range and for inferring patterns of speciation. Here, we test a hypothesis of niche conservatism across evolutionary time in a group of manakins (Aves: Pipridae), with a focus on Chiroxiphia boliviana, and examine the degree of ecological differentiation with other Chiroxiphia and Antilophia manakins. We tested whether allopatric sister species were more or less similar in environmental space than expected given their phylogenetic distances, which would suggest, respectively, ecological niche conservatism over time or ecologically mediated selection (i.e. niche divergence). We modeled the distribution of nine manakin taxa (C. boliviana, C. caudata, C. lanceolata, C. linearis, C. p. pareola, C. p. regina, C. p. napensis, Antilophia galeata and A. bokermanni) using Maxent. We first performed models for each taxon and compared them. To test our hypothesis we followed three approaches: (1) we tested whether C. boliviana could predict the distribution of the other manakin taxa and vice versa; (2) we compared the ecological niches by using metrics of niche overlap, niche equivalency and niche similarity; and (3) lastly, we tested whether niche differentiation corresponded to phylogenetic distances calculated from two recent phylogenies. All models had high training and test AUC values. Mean AUC ratios were high (>0.8) for most taxa, indicating performance better than random. Results suggested niche conservatism, and high niche overlap and equivalency between C. boliviana and C. caudata, but we found very low values between C. boliviana and the rest of the taxa. We found a negative, but not significant, relationship between niche overlap and phylogenetic distance, suggesting an increase in ecological differentiation and niche divergence over evolutionary time. Overall, we give some insights into the evolution of C. boliviana, proposing that ecological selection may have influenced its speciation.

scholarly journals Ecological niche overlap among species of the genus Zaluzania (Asteraceae) from the dry regions of Mexico

2020 ◽  
Vol 153 (3) ◽  
pp. 337-347
Author(s):  
Mario Ernesto Suárez-Mota ◽  
José Luis Villaseñor
Keyword(s):  
Ecological Niche ◽  
Potential Distribution ◽  
Area Under The Curve ◽  
Niche Overlap ◽  
Ecological Niches ◽  
Niche Conservatism ◽  
Distribution Models ◽  
Closely Related Species ◽  
Environmental Pressures ◽  
Fundamental Niche

Background and aims – The hypothesis of ecological niche conservatism postulates that closely related species share ecologically similar environments; that is, they tend to maintain the characteristics of their fundamental niche over time. The objective of this study is to evaluate the similarity and equivalence of the ecological niches among species of the genus Zaluzania (Asteraceae), characteristic of the Mexican arid and semi-arid regions, to infer their potential niche conservatism. Methods – Based on critically reviewed herbarium occurrence data, potential distribution models for eight species of Zaluzania were generated using the Maxent algorithm. The overlap between potential distribution areas was then evaluated using equivalence and ecological niche parameters implemented in the ENMTools software; for this we quantified the degree of overlap and similarity between the niches using the equivalence (D) and similarity (I) parameters.Key results – The resulting models show that species display areas of high suitability along the Mexican dry regions, as well as overlapping heterogeneous values. All models showed high AUC (Area Under the Curve) values (> 0.8). The D and I values between each pair of species showed low values of overlap.Conclusions – Each species of the genus shows a fundamental niche distinct from their sister species. The genus thus offers an example of niche divergence among species, with each one adapting to different environmental pressures. Our results do not support the hypothesis of niche conservatism in the genus, suggesting that the species evolved in divergent environments.

The effect of brain vitalization activity on dementia incidence in elderly at Budi Luhur Nursing Home of Yogyakarta, Kasongan, Bantul

2020 ◽  
Vol 1 (3) ◽  
pp. 43-50
Author(s):  
Firstyono Miftahul Aziz ◽  
Suratini Suratini
Keyword(s):  
Nursing Home ◽  
The Elderly ◽  
Control Group ◽  
P Value ◽  
Sampling System ◽  
Randomized Sampling ◽  
Care For The Elderly ◽  
Dementia Incidence ◽  
The Family ◽  
The Impact

For some people, dementia is considered as a disease that is common in elderly, regardless the impact of dementia. Taking care for the elderly with dementia brings stress for the family. It can cause and increase the family burden. Brain vitalization gymnastics is one of the methods to improve memory. The study aims to investigate the effect of brain vitalization activity on dementia incidence in elderly at Budi Luhur Nursing Home of Yogyakarta. The study used Quasi Experimental with Pretest-Posttest control group and randomized sampling system. The samples were taken randomly as many as 26 respondents and were divided into two groups namely 13 respondents of experimental group and 13 respondents of control group. The statistical test used Wilcoxon Match Pairs Test. The result showed that Wilcoxon Match pairs test obtained p value 0,003, which is smaller than 0,005. There is an effect of brain vitalization activity on dementia incidence in elderly at Budi Luhur Nursing Home of Yogyakarta

scholarly journals Endemic Juniperus Montane Species Facing Extinction Risk under Climate Change in Southwest China: Integrative Approach for Conservation Assessment and Prioritization

Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 63
Author(s):  
Mohammed A. Dakhil ◽  
Marwa Waseem A. Halmy ◽  
Walaa A. Hassan ◽  
Ali El-Keblawy ◽  
Kaiwen Pan ◽  
...  
Keyword(s):  
Climate Change ◽  
Potential Distribution ◽  
Extinction Risk ◽  
In Situ Conservation ◽  
Integrative Approach ◽  
Conservation Assessment ◽  
Distribution Models ◽  
Area Of Occupancy ◽  
Annual Range ◽  
The Impact

Climate change is an important driver of biodiversity loss and extinction of endemic montane species. In China, three endemic Juniperus spp. (Juniperuspingii var. pingii, J.tibetica, and J.komarovii) are threatened and subjected to the risk of extinction. This study aimed to predict the potential distribution of these three Juniperus species under climate change and dispersal scenarios, to identify critical drivers explaining their potential distributions, to assess the extinction risk by estimating the loss percentage in their area of occupancy (AOO), and to identify priority areas for their conservation in China. We used ensemble modeling to evaluate the impact of climate change and project AOO. Our results revealed that the projected AOOs followed a similar trend in the three Juniperus species, which predicted an entire loss of their suitable habitats under both climate and dispersal scenarios. Temperature annual range and isothermality were the most critical key variables explaining the potential distribution of these three Juniperus species; they contribute by 16–56.1% and 20.4–38.3%, respectively. Accounting for the use of different thresholds provides a balanced approach for species distribution models’ applications in conservation assessment when the goal is to assess potential climatic suitability in new geographical areas. Therefore, south Sichuan and north Yunnan could be considered important priority conservation areas for in situ conservation and search for unknown populations of these three Juniperus species.

scholarly journals Self-Secondaries Formed by Cold Spot Craters on the Moon

2021 ◽  
Vol 13 (6) ◽  
pp. 1087
Author(s):  
Yiren Chang ◽  
Zhiyong Xiao ◽  
Yang Liu ◽  
Jun Cui
Keyword(s):  
Systematic Investigation ◽  
Impact Craters ◽  
Spatial Density ◽  
Cold Spot ◽  
The Moon ◽  
Potential Threat ◽  
Frequency Distributions ◽  
Crater Size ◽  
The Impact ◽  
Density Pattern

Self-secondaries are a population of background secondaries, and they have been observed on top of impact melt and ballistically emplaced ejecta deposits on various planetary bodies. Self-secondaries are formed by impacts of sub-vertically launched ejecta, but the launch mechanism is not confirmed. The potential threat of self-secondaries to the theoretical and applicable reliability of crater chronology has been noted, but not constrained. Hitherto discovered self-secondaries were located around complex impact craters, but their potential existence around simple craters has not been discovered. Here we report the first discovery of self-secondaries around lunar cold spot craters, which are an extremely young population of simple craters formed within the past ~1 million years on the Moon. Self-secondaries are widespread on layers of cascading flow-like ejecta deposits around cold spot craters. The spatial density of self-secondaries dwarfs that of potential primary craters. The spatial distribution of self-secondaries is highly heterogeneous across the ejecta deposits. With respect to the impactor trajectory that formed cold spot craters, self-secondaries formed at the downrange of the ejecta deposits have the largest spatial density, while those at the uprange have the smallest density. This density pattern holds for all cold spot craters that were formed by non-vertical impacts, but self-secondaries do not exhibit other systematic density variations at different radial distances or at other azimuths with respect to the impactor trajectory. Among known mechanics of ejecting materials to the exterior of impact craters, impact spallation is the most likely scenario to account for the required large ejection velocities and angles to form self-secondaries. The production population of self-secondaries is estimated based on the highly diverse crater size-frequency distributions across the ejecta deposits of cold spot craters. For a better understanding of the impact history on the Moon, a systematic investigation for the effect of self-secondaries on lunar crater chronology is required.

scholarly journals Predicting the Future Distribution of Ara rubrogenys, an Endemic Endangered Bird Species of the Andes, Taking into Account Trophic Interactions

Diversity ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 94
Author(s):  
Alain Hambuckers ◽  
Simon de Harenne ◽  
Eberth Rocha Ledezma ◽  
Lilian Zúñiga Zeballos ◽  
Louis François
Keyword(s):  
Food Resource ◽  
Bird Species ◽  
Co2 Concentration ◽  
Distribution Models ◽  
Plant Resources ◽  
Term Survival ◽  
The Andes ◽  
Vegetation Models ◽  
Fertilizing Effect ◽  
The Impact

Species distribution models (SDMs) are commonly used with climate only to predict animal distribution changes. This approach however neglects the evolution of other components of the niche, like food resource availability. SDMs are also commonly used with plants. This also suffers limitations, notably an inability to capture the fertilizing effect of the rising CO2 concentration strengthening resilience to water stress. Alternatively, process-based dynamic vegetation models (DVMs) respond to CO2 concentration. To test the impact of the plant modelling method to model plant resources of animals, we studied the distribution of a Bolivian macaw, assuming that, under future climate, DVMs produce more conservative results than SDMs. We modelled the bird with an SDM driven by climate. For the plant, we used SDMs or a DVM. Under future climates, the macaw SDM showed increased probabilities of presence over the area of distribution and connected range extensions. For plants, SDMs did not forecast overall response. By contrast, the DVM produced increases of productivity, occupancy and diversity, also towards higher altitudes. The results offered positive perspectives for the macaw, more optimistic with the DVM than with the SDMs, than initially assumed. Nevertheless, major common threats remain, challenging the short-term survival of the macaw.

scholarly journals Do Microplastics Enter Our Food Chain Via Root Vegetables? A Raman Based Spectroscopic Study on Raphanus sativus

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2329
Author(s):  
Leda-Eleni Tympa ◽  
Klytaimnistra Katsara ◽  
Panagiotis N. Moschou ◽  
George Kenanakis ◽  
Vassilis M. Papadakis
Keyword(s):  
Raphanus Sativus ◽  
Acrylonitrile Butadiene Styrene ◽  
Terrestrial Ecosystems ◽  
Label Free ◽  
Plastic Pollution ◽  
Potential Threat ◽  
Safety Studies ◽  
Widespread Phenomenon ◽  
Agriculture And Food ◽  
The Impact

The outburst of plastic pollution in terrestrial ecosystems poses a potential threat to agriculture and food safety. Studies have already provided evidence for the uptake of plastic microparticles by several plant species, accompanied by numerous developmental effects, using fluorescence labelling techniques. Here, we introduce the implementation of confocal Raman spectroscopy, a label-free method, for the effective detection of microplastics (MPs) accumulation in the roots of a common edible root vegetable plant, Raphanus sativus, after treatment with acrylonitrile butadiene styrene (ABS) powder. We also demonstrate the concomitant occurrence of phenotypic defects in the polymer-treated plants. We anticipate that this work can provide new insights not only into the extent of the impact this widespread phenomenon has on crop plants but also on the methodological requirements to address it.

The Journalist—Source Relationship in Context: A Comparative Review of US and English Law

2009 ◽  
Vol 38 (3) ◽  
pp. 268-294
Author(s):  
Stuart Wallace
Keyword(s):  
Human Rights ◽  
Legal Protection ◽  
State Level ◽  
Potential Threat ◽  
Shield Law ◽  
Special Procedure ◽  
European Court ◽  
Comparative Review ◽  
The Uk ◽  
The Impact

This paper analyses the legal protection of the journalist–source relationship from both sides and the underlying interests involved. The paper begins by analysing why the relationship deserves protection. The position of journalists at common law is analysed with a discussion of the application of the principle established in Norwich Pharmacal v Customs and Excise to journalists. The development of immunity from contempt in s. 10 of the Contempt of Court Act 1981 is examined to illustrate the ideological clash between the judiciary and journalists. The impact of the Human Rights Act and decisions of the European Court of Human Rights are analysed to assess whether this will lead to a change in attitudes in the UK. Finally, the potential threat to journalists posed by compelled evidentiary disclosure in criminal cases is reviewed, with a particular look at ‘special procedure’ material. The US section begins with an analysis of the law at federal level, the decisions of the Supreme Court, including the leading decision of Branzburg v Hayes, as well as the role the legislature has played. The paper then analyses protections provided at state level, with a case study of the California shield law and a review of Californian jurisprudence.

scholarly journals Beavers, Bugs and Chemistry: A Mammalian Herbivore Changes Chemistry Composition and Arthropod Communities in Foundation Tree Species

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 877
Author(s):  
Rachel M. Durben ◽  
Faith M. Walker ◽  
Liza Holeski ◽  
Arthur R. Keith ◽  
Zsuzsi Kovacs ◽  
...  
Keyword(s):  
Tree Species ◽  
Castor Canadensis ◽  
Habitat Type ◽  
Food Preferences ◽  
Woody Species ◽  
Juvenile Growth ◽  
Arthropod Community ◽  
Riparian Ecosystems ◽  
Arthropod Communities ◽  
The Impact

The North American beaver (Castor canadensis Kuhl) and cottonwoods (Populus spp.) are foundation species, the interactions of which define a much larger community and affect a threatened riparian habitat type. Few studies have tested the effect of these interactions on plant chemistry and a diverse arthropod community. We experimentally examined the impact of beaver foraging on riparian communities by first investigating beaver food preferences for one cottonwood species, Fremont cottonwood (P. fremontii S. Watson), compared to other locally available woody species. We next examined the impact of beaver foraging on twig chemistry and arthropod communities in paired samples of felled and unfelled cottonwood species in northern Arizona (P. fremontii) and southwestern Colorado (narrowleaf cottonwood, P. angustifolia James, and Eastern cottonwood, P. deltoides W. Bartram ex Marshall). Four major patterns emerged: (1) In a cafeteria experiment, beavers chose P. fremontii six times more often than other woody native and exotic species. (2) With two cottonwood species, we found that the nitrogen and salicortin concentrations were up to 45% greater and lignin concentration 14% lower in the juvenile resprout growth of felled trees than the juvenile growth on unfelled trees (six of seven analyses were significant for P. fremontii and four of six were significant for P. angustifolia). (3) With two cottonwood species, arthropod community composition on juvenile branches differed significantly between felled and unfelled trees, with up to 38% greater species richness, 114% greater relative abundance and 1282% greater species diversity on felled trees (six of seven analyses with P. fremontii and four of six analyses with P. angustifolia were significant). The above findings indicate that the highest arthropod diversity is achieved in the heterogenous stands of mixed felled and unfelled trees than in stands of cottonwoods, where beavers are not present. These results also indicate that beaver herbivory changes the chemical composition in 10 out of 13 chemical traits in the juvenile growth of two of the three cottonwood species to potentially allow better defense against future beaver herbivory. (4) With P. deltoides, only one of five analyses in chemistry was significant, and none of the four arthropod community analyses were significant, suggesting that this species and its arthropod community responds differently to beaver. Potential reasons for these differences are unknown. Overall, our findings suggest that in addition to their impact on riparian vegetation, other mammals, birds, and aquatic organisms, beavers also may define the arthropod communities of two of three foundation tree species in these riparian ecosystems.

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