extinction events
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Author(s):  
Mario Ljubičić

Origin, mechanics and properties of the Solar System are analyzed in the framework of Complete Relativity. The analysis confirms the postulates and hypotheses of the theory with a high degree of confidence. During the analysis, some new hypotheses have emerged. These are discussed and confirmed with various degrees of confidence. To increase confidence or refute some hypotheses, experimental verification is necessary. Main conclusions are: - Solar System is a scaled Carbon isotope with a nucleus in a condensed (bosonic) state and components in various vertically excited states, - Earth is a living being of extremely introverted intelligence, life is common everywhere, albeit extroverted complex forms are present on planetary surfaces only during planetary neurogenesis, - anthropogenic climate change is only a part (trigger from one perspective) of bigger global changes on Earth and in the Solar System during planetary neurogenesis, - major extinction events are relative extinctions, a regular part of transformation and transfer of life in the process of planetary neurogenesis.


2021 ◽  
Vol 78 (2) ◽  
pp. e116
Author(s):  
Mike Thiv ◽  
Manuela Gouveia ◽  
Miguel Menezes de Sequeira

Macaronesian laurel forests harbour many herbs and laurophyllous trees with Mediterranean/European or Macaronesian affinities. Traditionally, the origin of these taxa has been explained by the relict hypothesis interpreting these taxa as relics of formerly widespread laurel forests in the European continent and the Mediterranean. We analysed the phylogenetic relationships of the Madeiran laurel forest endemic Goodyera macrophylla (Orchidaceae) using sequences from the nuclear ribosomal DNA Internal Transcribed Spacers (ITS) and plastid DNA regions. The results were incongruent, either the two Central American G. brachyceras and G. striata (ITS) or the North American G. oblongifolia (plastid DNA) were sister group to G. macrophylla. Nonetheless, biogeographic analyses indicated an American origin of this nemoral laurel forest plant in the two data sets. Molecular clock analyses suggest a colonisation of Madeira in the span of the upper Miocene/lower Pliocene to the Pleistocene. Although the relict hypothesis cannot be ruled out by our data when assuming extinction events on the European and northern African mainland, dispersal from Central or North America to the archipelago of Madeira is a much more likely explanation of the data.


Diversity ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 654
Author(s):  
Jian-Feng Huang ◽  
Clive T. Darwell ◽  
Yan-Qiong Peng

As well as bountiful natural resources, the Indo-Burma biodiversity hotspot features high rates of habitat destruction and fragmentation due to increasing human activity; however, most of the Indo-Burma species are poorly studied. The exploration of plants closely associated with human activity will further assist us to understand our influence in the context of the ongoing extinction events in the Anthropocene. This study, based on widely and intensively sampled F. altissima across Indo-Burma and the adjacent south China ranges, using both the chloroplast psbA-trnH spacer and sixteen newly developed nuclear microsatellite markers (nSSRs), aims to explore its spatial genetic structure. The results indicated low chloroplast haplotype diversity and a moderate level of nuclear genetic diversity. Although limited seed flow was revealed by psbA-trnH, no discernible phylogeographic structure was shown due to the low resolution of cpDNA markers and dominance of an ancestral haplotype. From the nSSRs data set, phylogeographic structure was homogenized, most likely due to extensive pollen flow mediated by pollinating fig wasps. Additionally, human cultivation and human-mediated transplanting further confounded the analyses of population structure. No geographic barriers are evident across the large study range, with F. altissima constituting a single population, and extensive human cultivation is likely to have had beneficial consequences for protecting the genetic diversity of F. altissima.


2021 ◽  
Vol 8 (2) ◽  
pp. 118-138

Anthropology meets democratic theory in this conversation that explores indigeneity, diversity, and the potentialities of democratic practices as exist in the non-Western world. Wade Davis draws readers into the ethnosphere—the sum total of human knowledge and experience—to highlight the extinction events that are wiping out some half of human ethnic diversity. Gagnon worries over what is lost to how we can understand and practice democracy in this unprecedented, globally occurring, ethnocide.


Geology ◽  
2021 ◽  
Author(s):  
A.D. Muscente ◽  
Rowan C. Martindale ◽  
Anirudh Prabhu ◽  
Xiaogang Ma ◽  
Peter Fox ◽  
...  

Ecological observations and paleontological data show that communities of organisms recur in space and time. Various observations suggest that communities largely disappear in extinction events and appear during radiations. This hypothesis, however, has not been tested on a large scale due to a lack of methods for analyzing fossil data, identifying communities, and quantifying their turnover. We demonstrate an approach for quantifying turnover of communities over the Phanerozoic Eon. Using network analysis of fossil occurrence data, we provide the first estimates of appearance and disappearance rates for marine animal paleocommunities in the 100 stages of the Phanerozoic record. Our analysis of 124,605 fossil collections (representing 25,749 living and extinct marine animal genera) shows that paleocommunity disappearance and appearance rates are generally highest in mass extinctions and recovery intervals, respectively, with rates three times greater than background levels. Although taxonomic change is, in general, a fair predictor of ecologic reorganization, the variance is high, and ecologic and taxonomic changes were episodically decoupled at times in the past. Extinction rate, therefore, is an imperfect proxy for ecologic change. The paleocommunity turnover rates suggest that efforts to assess the ecological consequences of the present-day biodiversity crisis should focus on the selectivity of extinctions and changes in the prevalence of biological interactions.


The Holocene ◽  
2021 ◽  
pp. 095968362110604
Author(s):  
Alejandro Valenzuela ◽  
Enric Torres-Roig ◽  
Daniel Zoboli ◽  
Gian Luigi Pillola ◽  
Josep Antoni Alcover

Comparative studies on extinction scenarios are an invaluable contribution to enhance our understanding of their patterns and mechanisms underpinning them. This paper presents new radiocarbon dates based on specimens of five extinct mammal species from Mallorca and Sardinia. The new evidence permits to reanalyse the extinction dynamics on both islands. Radiocarbon ages directly obtained on bone collagen from these species show evidence of different extinction patterns on Mallorca and Sardinia. For Mallorca the most reliable scenario is a mass extinction of all non-volant mammal species as an immediate consequence of the first human irruption on the island. However, for Sardinia, the extinction of autochthonous mammals lasted over several millennia. The new radiocarbon dates of the last occurrence of endemic mammals suggest a sequence of punctuated extinction events throughout the late Sardinian Holocene. These events are here tentatively related to successive human colonisation waves. The current lack of chronological dates for some Sardinian fossil mammals impedes to outline a more accurate pattern of extinction events. The present paper points that Mallorca have been more vulnerable than Sardinia to the external disturbances introduced by humans. We suggest that the capacity of each island to absorb external perturbations could be related to the island area, the duration of the isolated evolution and the degree of faunal complexity.


2021 ◽  
Author(s):  
Timothy Chapman ◽  
Luke Milan ◽  
Ian Metcalfe ◽  
Phil Blevin ◽  
James Crowley

Abstract Brief pulses of intense magmatic activity (flare-ups) along convergent margins represent drivers for climatic excursions that can lead to major extinction events. However, correlating volcanic outpouring to environmental crises in the geological past is often difficult due to poor preservation of volcanic sequences. Herein, we present a high-fidelity, CA-TIMS U–Pb zircon record of an end-Permian flare-up event in Eastern Australia, that involved the eruption of >39,000–150,000 km3 of silicic magma in c. 4.21 million years. A correlated high-resolution tephra record (c. 260–249 Ma) in the proximal sedimentary basins suggests recurrence of eruptions from the volcanic field in intervals of ~51,000–145,000 years. Peak eruption activity at 253 Ma is chronologically associated with the pulsed stages of the Permian mass extinction event. The ferocity of the 253 Ma eruption cycle in Eastern Australia is identified as a driver of greenhouse crises and ecosystem stress that led to the reduction in diversity of genera and the demise of the Glossopteris Forests. Simultaneous global continental margin arc flare-up events could thus present an additional agent to trigger greenhouse warming and ecosystem stress that preceded the catastrophic eruption of the Siberian Traps.


2021 ◽  
pp. jgs2021-055
Author(s):  
M. J. Pankhurst ◽  
C. J. Stevenson ◽  
B. C. Coldwell

Meteorite impacts load the atmosphere with dust and cover the Earth's surface with debris. They have long been debated as a trigger of mass extinctions through Earth's history. Impact winters generally last <100 years, whereas ejecta blankets persist for 103-105 years. Here we show that only meteorite impacts that emplaced ejecta blankets rich in K-feldspar (Kfs) correlate to Earth system crises (n=11, p<0.000005). Kfs is a powerful ice-nucleating aerosol yet is normally rare in atmospheric dust mineralogy. Ice nucleation plays an important role in cloud microphysics, which modulates global albedo. A conceptual model is proposed whereby the anomalous prevalence of Kfs is posited to have two key effects on cloud dynamics: 1) reducing the average albedo of mixed-phase cloud, which effected a hotter climate; 2) weakening of the cloud albedo feedback, which increased climate sensitivity. These mechanisms offer an explanation as to why this otherwise benign mineral is correlated so strongly with mass extinction events: every K-feldspar-rich ejecta blanket corresponds to a severe extinction episode over the past 600 Myr. This model may also explain why many kill mechanisms only variably correlate with extinction events through geological time: they coincide with these rare periods of climate destabilization by atmospheric Kfs.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5690646


2021 ◽  
Vol 2108 (1) ◽  
pp. 012101
Author(s):  
Mingliang Zhao ◽  
Shuai Guo ◽  
Zhiyu Song ◽  
Xiu Liu ◽  
Ping Guo

Abstract The number 4 boiler of a certain power plant happened the boiler fire extinction events. Because of main and auxiliary DPU switched failure, more piece of card took off the network and malfunctioned, both of PAF(Primary Air Fan) stop, which triggered MFT, that lead to the boiler fire-extinguishing. Aimed at the course of the boiler fire-extinguishing and the measure that had been adopted, this paper expounds in detail, analyzes the cause of the incident and other aspects of the problem that the incident exposed to, finally, in view of the existing problems and potential sa1fety hazard, this paper gives specific recommendations.


2021 ◽  
Vol 288 (1961) ◽  
Author(s):  
Elleard F. W. Heffern ◽  
Holly Huelskamp ◽  
Sonya Bahar ◽  
R. Fredrik Inglis

Phase transitions are an important and extensively studied concept in physics. The insights derived from understanding phase transitions in physics have recently and successfully been applied to a number of different phenomena in biological systems. Here, we provide a brief review of phase transitions and their role in explaining biological processes ranging from collective behaviour in animal flocks to neuronal firing. We also highlight a new and exciting area where phase transition theory is particularly applicable: population collapse and extinction. We discuss how phase transition theory can give insight into a range of extinction events such as population decline due to climate change or microbial responses to stressors such as antibiotic treatment.


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