Zooplankton indicator-based assessment in relation to site location and abiotic factors: a case study from the Gulf of Riga

2020 ◽  
Vol 192 (2) ◽  
Author(s):  
Astra Labuce ◽  
Inta Dimante-Deimantovica ◽  
Juris Tunens ◽  
Solvita Strake
Keyword(s):  
Abiotic Factors ◽  
Site Location ◽  
Gulf Of Riga

scholarly journals Is Sexual Conflict a Driver of Speciation? A Case Study With a Tribe of Brush-footed Butterflies

2020 ◽  
Author(s):  
Ana Paula S Carvalho ◽  
Ryan A St Laurent ◽  
Emmanuel F A Toussaint ◽  
Caroline Storer ◽  
Kelly M Dexter ◽  
...  
Keyword(s):  
Sexual Conflict ◽  
Abiotic Factors ◽  
Evolutionary Mechanisms ◽  
Diversification Rates ◽  
Exon Capture ◽  
Key Driver ◽  
Underlying Mechanisms ◽  
Analytical Approaches ◽  
Acting In Concert

Abstract Understanding the evolutionary mechanisms governing the uneven distribution of species richness across the tree of life is a great challenge in biology. Scientists have long argued that sexual conflict is a key driver of speciation. This hypothesis, however, has been highly debated in light of empirical evidence. Recent advances in the study of macroevolution make it possible to test this hypothesis with more data and increased accuracy. In the present study, we use phylogenomics combined with four different diversification rate analytical approaches to test whether sexual conflict is a driver of speciation in brush-footed butterflies of the tribe Acraeini. The presence of a sphragis, an external mating plug found in most species among Acraeini, was used as a proxy for sexual conflict. Diversification analyses statistically rejected the hypothesis that sexual conflict is associated with shifts in diversification rates in Acraeini. This result contrasts with earlier studies and suggests that the underlying mechanisms driving diversification are more complex than previously considered. In the case of butterflies, natural history traits acting in concert with abiotic factors possibly play a stronger role in triggering speciation than does sexual conflict. [Acraeini butterflies; arms race; exon capture phylogenomics; Lepidoptera macroevolution; sexual selection; sphragis.]

scholarly journals Modeling the shelter site location problem using chance constraints: A case study for Istanbul

2018 ◽  
Vol 270 (1) ◽  
pp. 132-145 ◽  
Author(s):  
Ömer Burak Kınay ◽  
Bahar Yetis Kara ◽  
Francisco Saldanha-da-Gama ◽  
Isabel Correia
Keyword(s):  
Location Problem ◽  
Chance Constraints ◽  
Site Location ◽  
Shelter Site

scholarly journals TUNNEL PORTAL INSTABILITY IN LANDSLIDE AREA AND REMEDIAL SOLUTION: A CASE STUDY

2019 ◽  
Vol 59 (5) ◽  
pp. 435-447 ◽  
Author(s):  
Farhad Farhadi Ayoublou ◽  
Majid Taromi ◽  
Abbas Eftekhari
Keyword(s):  
Geological Structure ◽  
Construction Process ◽  
Site Location ◽  
Landslide Area ◽  
Tunnel Excavation ◽  
Excavation Process ◽  
Geological Formations ◽  
Zagros Region ◽  
Tunnel Portal

The construction of tunnel portals in mountainous or slope areas often involves problems, which are closely related to factors, such as slope topography, geology, geotechnics, construction geometry and the tunnel excavation method. The activation of landslides or the acceleration of these events is one of the main challenges faced in the construction of tunnel portals. In this paper, we address the instability problem in Sabzkuh tunnel portal that has been excavated with a complex geological profile and high seismicity in Iran’s High Zagros region. The complexity and intense heterogeneity in geological formations, land acquisition problems and the lack of appropriate monitoring programs led to the instability of the tunnel portal. The excavation process started without applying appropriate techniques for a ground stabilization. The use of inappropriate tunnel excavation methods for this unstable geological structure resulted in an activation of an old Solaghan fault and several collapses in the tunnel. Crossing the collapsed areas and reinforcing the tunnel portal took about 7 months and imposed heavy costs on the project. This case study deals with the importance of the choice of the site location, ground and underground monitoring, analysing and summarizing the collected data in order to prepare a geological model before and during the construction process.

scholarly journals Construction of ropeways in Slovakia in terms of pre-construction design using helicopters (case study)

2019 ◽  
Vol 263 ◽  
pp. 01002
Author(s):  
Andrej Bisták ◽  
Zdenka Hulínová
Keyword(s):  
Construction Industry ◽  
Transport Mechanism ◽  
Simulation Models ◽  
Weather Conditions ◽  
Positive Experience ◽  
Site Location ◽  
Factors Affecting ◽  
Construction Design ◽  
History Of

Ropeways usually provide access to locations inaccessible to other means of transport. Due to this fact, the construction of ropeways is extraordinarily taxing in terms of both, technology and logistics. The site location is often in terrain difficult to access, which often precludes deployment of common construction mechanisms in ropeway construction. In such case, it is advisable to deploy a transport mechanism independent of the terrain – a helicopter. Functioning as “flying cranes“, the helicopters have been used in construction industry in Slovakia for six decades now. Having amassed positive experience, even the “conventional“ construction industry of the time, especially its ropeway transport segment, started to use the benefits of helicopters, with helicopter deployment subsequently gaining ground and becoming the mainstream technological procedure. Ropeway construction can hardly be feasible without them even nowadays. Throughout the history of helicopter deployment in construction industry, a constant search of improving the efficiency of their work has been under way, necessitated by the helicopter’s sensitivitiy to weather conditions and work procedures alike. The paper presents an analysis of the factors affecting helicopter operation together with a proposed methodology of modeling their work in simulation models and the benefits of such approach.

scholarly journals The Status and Threats of Birds: A Case Study of Birds in Nayapul to Ghandruk Area, Kaski, Nepal

2021 ◽  
pp. 18-32
Author(s):  
Subhas Chandra Bastola
Keyword(s):  
Crop Production ◽  
Abiotic Factors ◽  
Bird Species ◽  
Habitat Destruction ◽  
Bird Population ◽  
Factors Affecting ◽  
Storage Devices ◽  
The Status ◽  
Total Species

The purpose of this study is to quantify species diversity of birds in the study area and to explore the biotic and abiotic factors affecting the bird population. This study was carried out by using the fixed point counting method. The study area was situated in Annapurna Rural Municipality of Kaski district. A total of 147 bird species belonging to 46 families and 14 orders were identified in the study area. It was found that Muscicapidae was the largest family and Passeriformes the largest order. Among the reported species, 50% were residents, 31% were full-migrants, 18% were altitudinal migrants and the remaining were 1% nomadic. Habitats of birds included the forest 68%, the scrubland 17 %, the grassland 7% and the wetland 6 % of the study area. Similarly, the rocky area and artificial area covered 1% of the total species. The results showed that most of the bird species i.e. 136 were least concerned, 4 of them were nearly threatened, 3 of them were endangered, 3 were critically endangered and only one species was vulnerable. The most important threats included hunting and trapping, killing for fun, shift in crop production, use of insecticides and pesticides, improved storage devices, habitat destruction, developmental activities, tourism, buried carcasses and predatory.

scholarly journals Biological Invasion Theories: Merging Perspectives from Population, Community and Ecosystem Scales

2019 ◽  
Author(s):  
Olivier Chabrerie ◽  
François Massol ◽  
Benoit Facon ◽  
Romain Thevenoux ◽  
Manon Hess ◽  
...  
Keyword(s):  
Biological Invasions ◽  
Introduced Species ◽  
Native Species ◽  
Abiotic Factors ◽  
Empirical Studies ◽  
Native Populations ◽  
Specific Stage ◽  
Ecosystem Transformation ◽  
Theoretical Dynamics

Biological invasions have reached an unprecedented level and the number of introduced species is still increasing worldwide. Despite major advances in invasion science, the determinants of success of introduced species, the magnitude and dimensions of their impact, and the mechanisms sustaining successful invasions are still debated. Empirical studies show divergent impacts of non-native populations on ecosystems and contrasting effects of biotic and abiotic factors on the dynamics of non-native populations; this is hindering the emergence of a unified theory of biological invasions. We propose a synthesis that merges perspectives from population, community, and ecosystem levels. Along a timeline of ecosystem transformation driven by non-native species, from historical to human-modified ecosystems, we order invasion concepts and theories to clarify their chaining and relevance during each step of the invasion process. This temporal sorting of invasion concepts shows that each concept is relevant at a specific stage of the invasion. Concepts and empirical findings on non-native species may appear contradictory. However, we suggest that, when mapped onto an invasion timeline, they may be combined in a complementary way. An overall scheme is proposed to summarise the theoretical dynamics of ecosystems subjected to invasions. For any given case study, this framework provides a guide through the maze of theories and should help choose the appropriate concepts according to the stage of invasion.

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