scholarly journals The names don't matter but the numbers do: searching for stability in Carboniferous brachiopod paleocommunities from the North American Midcontinent

Paleobiology ◽  
2020 ◽  
pp. 1-18
Author(s):  
Luke C. Strotz ◽  
Bruce S. Lieberman
Keyword(s):  
Taxonomic Composition ◽  
Ecological Stability ◽  
The North ◽  
Community Turnover ◽  
Ecological Scale ◽  
Rapid Changes ◽  
Long Time ◽  
Ecological Patterns ◽  
The Face ◽  
Open Question

Abstract A key question in paleoecology and macroevolution is whether assemblages of species (paleocommunities) are persistent entities that endure over millions of years. While community turnover in the face of abiotic change is the presumed norm, paleocommunities have been shown to persist for long time periods and regardless of environmental disruption. It remains an open question, however, as to what processes allow for this. We investigate these questions by analyzing the Carboniferous brachiopod paleocommunities from the Midcontinent of North America. These diverse communities were subjected to repeated and geologically rapid changes in sea level. Using a suite of statistical techniques, we characterize the nature and scope of changes in these paleocommunities over time. We find that, at the paleocommunity scale, there is no evidence for obdurate ecological stasis, with fluctuations in both taxonomic composition and the associated abundance of taxa. However, at a higher ecological scale, stability is manifest, as diversity patterns remain stable across time, with a consistent number of species that can exist in any given paleocommunity. This suggests ecological rules such as taxon packing are in effect, resulting in a form of ecological stability even in the face of constant disequilibrium, and parallels ecological patterns of disruption and recovery previously observed for invertebrate communities from modern marine systems. Based on these results, we advocate for consideration of different hierarchical entities and scales when interpreting the ecological dynamics of fossil assemblages, as focusing exclusively on changes in taxon identity/abundance or diversity levels can lead to very different results.

Ecological stability despite environmental disruption – searching for ecological rules governing Carboniferous brachiopod assemblages from the North American Mid-continent

2020 ◽  
Author(s):  
Luke Strotz ◽  
Bruce Lieberman
Keyword(s):  
Environmental Changes ◽  
Marine Invertebrate ◽  
Taxonomic Composition ◽  
Suitable Habitat ◽  
Ecological Stability ◽  
Ecological Processes ◽  
The North ◽  
Environmental Setting ◽  
The Individual ◽  
Environmental Disruption

<p>A key topic in paleoecology and macroevolution is whether assemblages of species show patterns of persistence over millions of years; a phenomenon that has been variously referred to as ‘Turnover Pulse’ or ‘Coordinated Stasis’. It has generally been presumed that any abrupt environmental changes discernible in the geological record will often lead to community turnover and the establishing of a new community that is discrete from the previous iteration, even if environmental conditions return to those that existed prior to the disruptive event. A related topic is, if patterns of stability can and do prevail despite disruption, what are the processes that allow for this. Potential options include the degree of change in the physical environment, which may not be great enough to exceed the threshold required for community collapse, or due to ‘Ecological Locking’, where directional selection is constrained by ecological processes.</p><p>Our touchstone to consider these topics is the detailed fossil record of Carboniferous brachiopod communities from the Mid-continent of North America. These were highly diverse communities that persisted in a very dynamic environmental setting. In particular, these communities were subjected to frequent and geologically rapid phases of marine transgression and regression associated with climate change over approximately a 20-million-year period. These changes likely resulted in repeated community destruction and renewal as suitable habitat was lost and then subsequently re-established.</p><p>Using a suite of statistical techniques, we characterized the nature and scope of changes in these fossil communities over time. We found that, at one scale, fossil communities were not stable throughout this interval, both in terms of taxonomic composition and the associated abundance of those taxa. Thus, there is no evidence of obdurate ecological stasis, as new discrete communities, statistically dissimilar from previous and subsequent iterations, form following each environmental disruption. However, at a higher scale, stability is manifest, as diversity patterns are stable across time and despite episodes of environmental change. In particular, we identify a form of qualified ecological stasis for both the different environments present during this interval and for the larger region as a whole. Ultimately, whilst the individual taxa that comprise each community differ, there is a consistent number of species that can exist in any given community, such that communities remain functionally similar. This indicates that whilst the individual taxa that come to form communities arrive via the exigencies of recruitment, the overall diversity of the communities is set by some higher-level ecological rules. Specifically, the rules for taxon packing are seemingly constant in distinct environments, likely due to energetic controls that limit how many taxa can be maintained in an environmental setting and/or perhaps because the amount of space needed for any individual to develop into an adult is invariant across different taxa within the same clade. Further, these ecological rules lead to stability even in the face of constant disequilibrium, which matches patterns identified in the recovery of marine invertebrate communities from disruptive events in modern systems.</p>

scholarly journals Modern microbial mats from the Chihuahuan Desert provide insights into ecological stability throughout Earth's history

2021 ◽  
Author(s):  
David Madrigal-Trejo ◽  
Jazmín Sánchez-Pérez ◽  
Laura Espinosa-Asuar ◽  
Valeria Souza
Keyword(s):  
Fossil Record ◽  
Microbial Mats ◽  
Chihuahuan Desert ◽  
Extreme Environments ◽  
Taxonomic Composition ◽  
Ecological Stability ◽  
The Face ◽  
Microbial System ◽  
Cuatro Ciénegas ◽  
Cuatro Ciénegas Basin

Microbial mats are complex ecological assemblages that are found in the Precambrian fossil record and in extant extreme environments. Hence, these structures are regarded as highly stable ecosystems. In this work, we assess the ecological stability in a modern, fluctuating, hypersaline pond from the Cuatro Ciénegas Basin. From the 2016 to 2019 metagenomic sampling of this site, we found that this microbial site is sensitive to disturbances, which leads to high taxonomic replacement. Additionally, the mats have shown to be functionally stable throughout time, and could be differentiated between dry and rainy seasonal states. We speculate that this microbial system could represent a modern analog of ancient, hypersaline coastal microbial mats, where functions were preserved over time, whereas taxonomic composition was subject to diversification in the face of local and planetary perturbations.

Mars: was There an Ancient Eden?

1997 ◽  
Vol 161 ◽  
pp. 203-218 ◽  
Author(s):  
Tobias C. Owen
Keyword(s):  
Positive Answer ◽  
Biogenic Elements ◽  
Habitable Zones ◽  
The Face ◽  
The Origin Of Life ◽  
Early Mars ◽  
Favorable Conditions ◽  
Open Question ◽  
Rocky Planets ◽  
Impact Erosion

AbstractThe clear evidence of water erosion on the surface of Mars suggests an early climate much more clement than the present one. Using a model for the origin of inner planet atmospheres by icy planetesimal impact, it is possible to reconstruct the original volatile inventory on Mars, starting from the thin atmosphere we observe today. Evidence for cometary impact can be found in the present abundances and isotope ratios of gases in the atmosphere and in SNC meteorites. If we invoke impact erosion to account for the present excess of129Xe, we predict an early inventory equivalent to at least 7.5 bars of CO2. This reservoir of volatiles is adequate to produce a substantial greenhouse effect, provided there is some small addition of SO2(volcanoes) or reduced gases (cometary impact). Thus it seems likely that conditions on early Mars were suitable for the origin of life – biogenic elements and liquid water were present at favorable conditions of pressure and temperature. Whether life began on Mars remains an open question, receiving hints of a positive answer from recent work on one of the Martian meteorites. The implications for habitable zones around other stars include the need to have rocky planets with sufficient mass to preserve atmospheres in the face of intensive early bombardment.

SISTEM PENDUKUNG KEPUTUSAN PEMILIHAN KEPALA CABANG TERBAIK BANK SUMUT DENGAN MENERAPKAN METODE VIKOR

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Betrik J Hutapea ◽  
Mesran Mesran ◽  
Siti Nurhabibah
Keyword(s):  
Decision Support ◽  
Decision Support System ◽  
Support System ◽  
Development Bank ◽  
Vikor Method ◽  
The North ◽  
Long Time ◽  
North Sumatra ◽  
Regional Development Bank ◽  
Selection Of

SUMUT Bank is one of the Banks in Indonesia with the name of the company PT. Regional Development Bank of North Sumatra. The North Sumatra Bank has branches in each region in North Sumatra both in the district and in the sub-district, and each of these branches is led by a branch leader or branch head. The head of this branch is responsible for the reversal of the Bank being led. The best and most accomplished branch heads deserve more and more awards. The selection of the best branch heads is selected transparently and structured in the hope that it can be a motivation for all branch heads to be able to further improve the quality and service of the Bank they lead. Making the best branch head selection done manually will take a long time and tends to be less transparent and structured. One solution so that the implementation of the selection can be carried out easily and quickly, it requires a Decision Support System that can provide consistency of assessment. In this study the method used is the VIKOR method (Visekriterijumsko Kompromisno Rangiranje). This method makes cracking on alternatives based on criteria that have been determined with an ideal compromise solution or the best solution, so that this system can later be beneficial for the SUMUT Bank to get the title in determining the best branch head.Keywords: Decision Support System, North Sumatra Bank, Branch Head, Vikor

INTERCONNECTION OF SUSTAINABLE DEVELOPMENT COMPONENTS FOR THE INDIGENOUS PEOPLES OF THE NORTH

2020 ◽  
Vol 2 (8) ◽  
pp. 101-110
Author(s):  
N. N. ILYSHEVA ◽  
◽  
E. V. KARANINA ◽  
G. P. LEDKOV ◽  
E. V. BALDESKU ◽  
...  
Keyword(s):  
Climate Change ◽  
Sustainable Development ◽  
Economic Development ◽  
Indigenous Peoples ◽  
Ecological Footprint ◽  
Positive Relationship ◽  
The North ◽  
Strong Positive Relationship ◽  
The Face ◽  
The Relationship

The article deals with the problem of achieving sustainable development. The purpose of this study is to reveal the relationship between the components of sustainable development, taking into account the involvement of indigenous peoples in nature conservation. Climate change makes achieving sustainable development more difficult. Indigenous peoples are the first to feel the effects of climate change and play an important role in the environmental monitoring of their places of residence. The natural environment is the basis of life for indigenous peoples, and biological resources are the main source of food security. In the future, the importance of bioresources will increase, which is why economic development cannot be considered independently. It is assumed that the components of resilience are interrelated and influence each other. To identify this relationship, a model for the correlation of sustainable development components was developed. The model is based on the methods of correlation analysis and allows to determine the tightness of the relationship between economic development and its ecological footprint in the face of climate change. The correlation model was tested on the statistical materials of state reports on the environmental situation in the Khanty-Mansiysk Autonomous Okrug – Yugra. The approbation revealed a strong positive relationship between two components of sustainable development of the region: economy and ecology.

The Many Faces of Socioeconomic Change

2017 ◽  
Author(s):  
John Toye
Keyword(s):  
Socioeconomic Development ◽  
Adam Smith ◽  
First Century ◽  
Social Progress ◽  
Long Time ◽  
The Face ◽  
Scientific Expertise ◽  
The Many ◽  
Century Development

This book provides a survey of different ways in which economic sociocultural and political aspects of human progress have been studied since the time of Adam Smith. Inevitably, over such a long time span, it has been necessary to concentrate on highlighting the most significant contributions, rather than attempting an exhaustive treatment. The aim has been to bring into focus an outline of the main long-term changes in the way that socioeconomic development has been envisaged. The argument presented is that the idea of socioeconomic development emerged with the creation of grand evolutionary sequences of social progress that were the products of Enlightenment and mid-Victorian thinkers. By the middle of the twentieth century, when interest in the accelerating development gave the topic a new impetus, its scope narrowed to a set of economically based strategies. After 1960, however, faith in such strategies began to wane, in the face of indifferent results and general faltering of confidence in economists’ boasts of scientific expertise. In the twenty-first century, development research is being pursued using a research method that generates disconnected results. As a result, it seems unlikely that any grand narrative will be created in the future and that neo-liberalism will be the last of this particular kind of socioeconomic theory.

Centroceras gasparrinii subsp. minor subsp. nov. (Ceramiaceae, Rhodophyta) in the North Adriatic Sea (Mediterranean): molecular and morphological characterization

Phytotaxa ◽  
2019 ◽  
Vol 415 (4) ◽  
pp. 233-239
Author(s):  
MARION A. WOLF ◽  
ALESSANDRO BUOSI ◽  
ABDUL-SALAM F. JUHMANI ◽  
ADRIANO SFRISO
Keyword(s):  
Morphological Characterization ◽  
Type Locality ◽  
Correct Identification ◽  
Cortical Cells ◽  
Western Atlantic ◽  
Gland Cells ◽  
The North ◽  
Red Algal ◽  
Long Time ◽  
The 19Th Century

Centroceras Kützing is a small red algal genus with 18 currently accepted species (Guiry & Guiry 2019), characterized by simple filamentous thalli with erect axes arising from a prostrate system and di-trichotomous branching (Hommersand 1963). The characters used to distinguish species are primarily cortical filament morphology: shape and number of the acropetal cortical cells, shape of gland cells, and shape of spines (Won et al. 2009). The generitype C. clavulatum (C. Agardh) Montagne has been viewed for a long time as a highly variable and cosmopolitan species (Hommersand 1963). Molecular and detailed morphological analyses brought Barros-Barreto et al. (2006) to report that C. clavulatum may consist of a species complex and Won et al. (2009) confirmed this hypothesis identifying eight taxonomic entities phylogenetically segregated from genuine C. clavulatum. Seven of these entities were assigned to the following species: C. gasparrinii (Meneghini) Kützing, C. hommersandii Won, T.O. Cho & Fredericq, C. hyalacanthum Kützing, C. micracanthum Kützing, C. natalensis Won, T.O. Cho & Fredericq, C. rodmanii Won, T.O. Cho & Fredericq, and C. tetrachotomum Won, T.O. Cho & Fredericq, (Won et al. 2009). Centroceras gasparrinii, C. hyalacanthum, and C. micracanthum are three western Atlantic species listed as synonyms of C. clavulatum since the middle of the 19th century and resurrected from the ‘C. clavulatum complex’ by Won et al. (2009). In particular, two of these taxa were described from specimens of the Mediterranean Sea: C. gasparrinii (as Ceramium gasparrinii Meneghini, type locality Palermo, Italy) and C. micracanthum (reported with the synonym Centroceras leptacanthum Kützing, type locality Genoa, Italy). Therefore, the numerous Mediterranean records of C. clavulatum (e.g., Gómez Garreta et al. 2001; Verlaque 2001; Sfriso & Curiel 2007; Taşkýn et al. 2013) most probably belong to one of these two species and have to be re-examined for a correct identification and to understand the spatial distribution of the different taxa (Tsiamis et al. 2010). For this reason, in the last years in Greece (Tsiamis et al. 2010), Spain (Gallardo et al. 2016) and Morocco (Hassoun et al. 2018) accurate sampling and morphological analyses of specimens previously identified as C. clavulatum were conducted to determine their correct taxonomic identities. In all cases the recognized species was C. gasparrinii, which can be distinguished morphologically from the other ones previously known as C. clavulatum by the presence of ovoid gland cells and ovoid terminal acropetal cortical cells (Won et al. 2009). As reported by Tsiamis et al. (2010), Greek samples differed from those described by Won et al. (2009), in the smaller number of periaxial cells (10–12 against 13–19).

The Evolutionary Diversity and Ecological Complexity of Coral Reefs

2011 ◽  
Vol 17 ◽  
pp. 111-120 ◽  
Author(s):  
Nancy Knowlton ◽  
Jeremy Jackson
Keyword(s):  
Coral Reefs ◽  
Small Proportion ◽  
Fossil Record ◽  
Marine Species ◽  
Foreseeable Future ◽  
Ecological Complexity ◽  
The Face ◽  
Open Question ◽  
Trophic Linkages ◽  
Bounce Back

Coral reefs are the most biodiverse marine ecosystems on the planet, with at least one quarter of all marine species associated with reefs today. This diversity, which remains very poorly understood, is nevertheless extraordinary when one considers the small proportion of ocean area that is occupied by coral reefs. Networks of competitive and trophic linkages are also exceptionally complex and dense. Reefs have a long fossil record, although extensive reef building comes and goes. In the present, coral reefs sometimes respond dramatically to disturbances, and collapses are not always followed by recoveries. Today, much of this failure to recover appears to stem from the fact that most reefs are chronically stressed by human activities, judging by observations of recovery at exceptional locations where local human activity is minimal. How long reefs can continue to bounce back in the face of warming and acidification remains an open question. Another big uncertainty is how much loss of biodiversity will occur with the inevitable degradation of coral reefs that will continue in most places for the foreseeable future.

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