scholarly journals Emergence and dynamics of self-producing information niches as a step towards pre-evolutionary organization

2018 ◽  
Vol 15 (138) ◽  
pp. 20170807
Author(s):  
Richard J. Carter ◽  
Karoline Wiesner ◽  
Stephen Mann
Keyword(s):  
Fitness Landscape ◽  
Basic Information ◽  
Living Matter ◽  
Environmental Perturbations ◽  
Transition Pathways ◽  
Strongly Connected ◽  
Genetic Mechanisms ◽  
Evolutionary Organization ◽  
Over Time ◽  
Exogenous Source

As a step towards understanding pre-evolutionary organization in non-genetic systems, we develop a model to investigate the emergence and dynamics of proto-autopoietic networks in an interacting population of simple information processing entities (automata). Our simulations indicate that dynamically stable strongly connected networks of mutually producing communication channels emerge under specific environmental conditions. We refer to these distinct organizational steady states as information niches . In each case, we measure the information content by the Shannon entropy, and determine the fitness landscape, robustness and transition pathways for information niches subjected to intermittent environmental perturbations under non-evolutionary conditions. By determining the information required to generate each niche, we show that niche transitions are only allowed if accompanied by an equal or increased level of information production that arises internally or via environmental perturbations that serve as an exogenous source of population diversification. Overall, our simulations show how proto-autopoietic networks of basic information processors form and compete, and under what conditions they persist over time or go extinct. These findings may be relevant to understanding how inanimate systems such as chemically communicating protocells can initiate the transition to living matter prior to the onset of contemporary evolutionary and genetic mechanisms.

scholarly journals Decreased sensitivity to the anorectic effects of leptin in mice that lack a Pomc-specific neural enhancer

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244793
Author(s):  
Elisa S. Na ◽  
Daniel D. Lam ◽  
Eva Yokosawa ◽  
Jessica M. Adams ◽  
David P. Olson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Body Weight ◽  
Knockout Mice ◽  
Weight Change ◽  
Body Weight Change ◽  
Dynamic Regulation ◽  
Adult Mice ◽  
Environmental Perturbations ◽  
Mild Obesity ◽  
Over Time

Enhancer redundancy has been postulated to provide a buffer for gene expression against genetic and environmental perturbations. While work in Drosophila has identified functionally overlapping enhancers, work in mammalian models has been limited. Recently, we have identified two partially redundant enhancers, nPE1 and nPE2, that drive proopiomelanocortin gene expression in the hypothalamus. Here we demonstrate that deletion of nPE1 produces mild obesity while knockout of nPE2 has no discernible metabolic phenotypes. Additionally, we show that acute leptin administration has significant effects on nPE1 knockout mice, with food intake and body weight change significantly impacted by peripheral leptin treatment. nPE1 knockout mice became less responsive to leptin treatment over time as percent body weight change increased over 2 week exposure to peripheral leptin. Both Pomc and Agrp mRNA were not differentially affected by chronic leptin treatment however we did see a decrease in Pomc and Agrp mRNA in both nPE1 and nPE2 knockout calorie restricted mice as compared to calorie restricted PBS-treated WT mice. Collectively, these data suggest dynamic regulation of Pomc by nPE1 such that mice with nPE1 knockout become less responsive to the anorectic effects of leptin treatment over time. Our results also support our earlier findings in which nPE2 may only be critical in adult mice that lack nPE1, indicating that these neural enhancers work synergistically to influence metabolism.

scholarly journals Patterns of δ13 C and δ15 N in wolverine Gulo gulo tissues from the Brooks Range, Alaska

2009 ◽  
Vol 55 (3) ◽  
pp. 188-192 ◽  
Author(s):  
Fredrik Dalerum ◽  
Anders Angerbjörn ◽  
Kyran Kunkel ◽  
Brad S. Shults
Keyword(s):  
Stable Isotopes ◽  
Temporal Change ◽  
Isotopic Fractionation ◽  
Stable Isotope Ratios ◽  
Brooks Range ◽  
Gulo Gulo ◽  
Environmental Perturbations ◽  
Diet Variation ◽  
Changes Over Time ◽  
Over Time

Abstract Knowledge of carnivore diets is essential to understand how carnivore populations respond demographically to variations in prey abundance. Analysis of stable isotopes is a useful complement to traditional methods of analyzing carnivore diets . We used data on δ13 C and δ15 N in wolverine tissues to investigate patterns of seasonal and annual diet variation in a wolverine Gulo gulo population in the western Brooks Range, Alaska, USA. The stable isotope ratios in wolverine tissues generally reflected that of terrestrial carnivores, corroborating previous diet studies on wolverines. We also found variation in δ13 C and δ15 N both between muscle samples collected over several years and between tissues with different assimilation rates, even after correcting for isotopic fractionation. This suggests both annual and seasonal diet variation. Our results indicate that data on δ13 C and δ15 N holds promise for qualitative assessments of wolverine diet changes over time. Such temporal variation may be important indicators of ecological responses to environmental perturbations, and we suggest that more refined studies of stable isotopes may be an important tool when studying temporal change in diets of wolverines and similar carnivores.

scholarly journals A Killer–Rescue system for self-limiting gene drive of anti-pathogen constructs

2008 ◽  
Vol 275 (1653) ◽  
pp. 2823-2829 ◽  
Author(s):  
Fred Gould ◽  
Yunxin Huang ◽  
Mathieu Legros ◽  
Alun L Lloyd
Keyword(s):  
Gene Action ◽  
Natural Populations ◽  
Gene Drive ◽  
Fitness Costs ◽  
Molecular Approaches ◽  
Genetic Mechanisms ◽  
Rescue System ◽  
Near Term ◽  
Killer Gene ◽  
Over Time

A number of genetic mechanisms have been suggested for driving anti-pathogen genes into natural populations. Each of these mechanisms requires complex genetic engineering, and most are theoretically expected to permanently spread throughout the target species' geographical range. In the near term, risk issues and technical limits of molecular methods could delay the development and use of these mechanisms. We propose a gene-drive mechanism that can be self-limiting over time and space, and is simpler to build. This mechanism involves one gene that codes for toxicity (killer) and a second that confers immunity to the toxic effects (rescue). We use population-genetic models to explore cases with one or two independent insertions of the killer gene and one insertion of the rescue gene. We vary the dominance and penetrance of gene action, as well as the magnitude of fitness costs. Even with the fitness costs of 10 per cent for each gene, the proportion of mosquitoes expected to transmit the pathogen decreases below 5 per cent for over 40 generations after one 2 : 1 release (engineered : wild) or after four 1 : 2 releases. Both the killer and rescue genes will be lost from the population over time, if the rescue construct has any associated fitness cost. Molecular approaches for constructing strains are discussed.

Resilient Individuals Improve Evolutionary Search

2006 ◽  
Vol 12 (1) ◽  
pp. 17-34 ◽  
Author(s):  
Terence Soule
Keyword(s):  
Evolutionary Computation ◽  
Artificial Life ◽  
Fitness Landscape ◽  
Evolutionary Search ◽  
Negative Effects ◽  
Evolutionary Dynamic ◽  
Genetic Robustness ◽  
Over Time ◽  
Evolving Populations

Results from the artificial life community show that under some conditions evolving populations converge on broader, but less fit peaks in the fitness landscape and avoid more fit, but narrower peaks. Results from the evolutionary computation community show that over time genotypes evolve to become more resilient, where resiliency (or genetic robustness) is defined as the ability of an individual to resist the potentially negative effects of genetic operations. This article demonstrates a previously unobserved evolutionary dynamic: in populations initially favoring a low, broad fitness peak, increases in resiliency result in the population shifting to a higher, narrower fitness peak. In these cases increasing resiliency is a necessary precondition for finding narrower peaks.

scholarly journals Crocodiles in Philippine Folklore

2021 ◽  
Vol 26 (1) ◽  
pp. 19-34
Author(s):  
Takashi Tsuji
Keyword(s):  
Indigenous People ◽  
The Philippines ◽  
Anthropological Perspective ◽  
The Past ◽  
Sick People ◽  
Strongly Connected ◽  
Relationship Of ◽  
Palawan Island ◽  
Over Time ◽  
Filipino People

This study investigates Philippine folklore of saltwater crocodiles to understand the relationships that people have with them from an anthropological perspective. The collected folklore was classified into eight types: 1) ancestor, 2) monkey heart, 3) red hen, 4) execution, 5) incarnation, 6) deception, 7) monster, and 8) Lusmore. The analysis shows that the crocodile folklore of the Philippines is strongly connected to that of the indigenous people in Borneo. Filipino people tend to recognize crocodiles as both fierce and foolish because they are harmful to their society. In their history, they have rigorously hunted crocodiles for their skin, causing their relationship with them to significantly diminish over time. However, crocodiles are also seen as having the supernatural power to cure sick people, so eating them is prohibited among the Pala’wan on Palawan Island, for instance. This paper concludes that the Filipino people and the crocodile were able to build a harmonious relationship of coexistence in the past, and the current corrupted relationship must change for its future wellbeing.

scholarly journals Adaptive Approaches Towards Better GA Performance in Dynamic Fitness Landscapes

1994 ◽  
Vol 23 (487) ◽  
Author(s):  
Henrik Hautop Lund
Keyword(s):  
Fitness Landscape ◽  
Dynamic Environments ◽  
Mutation Rates ◽  
Landscape Changes ◽  
Correlation Measure ◽  
The Right ◽  
Changes Over Time ◽  
Adaptive Approaches ◽  
Over Time ◽  
Selection Of

We review different techniques for improving GA performance. By analysing the fitness landscape, a correlation measure between parents and offspring can be provided, and we can estimate effectively which genetic operator to use in the GA for a given fitness landscape. The response to selection equation further tells us how well the GA will do, and combining the two approaches gives us a powerful tool to automatically ensure the selection of the right parameter settings for a given problem. In dynamic environments the fitness landscape changes over time, and the evolved systems should be able to adapt to such changes. By introducing evolvable mutation rates and evolvable fitness formulae, we obtain such systems. The systems are shown to be able to adapt to both internal and external constraints and changes.

Loops in publication citation networks

2019 ◽  
Vol 46 (6) ◽  
pp. 837-848 ◽  
Author(s):  
Yi Bu ◽  
Yong Huang ◽  
Wei Lu
Keyword(s):  
Computer Science ◽  
Web Of Science ◽  
Citation Network ◽  
Frequent Patterns ◽  
Citation Networks ◽  
Connected Component ◽  
Strongly Connected ◽  
Changes Over Time ◽  
Over Time ◽  
The Web

Traditionally, publication citation networks are regarded as acyclic, that is, no loops in the network as an earlier published article cannot cite a later published article. However, due to the accessibility of pre-print versions of articles, there might be some loops in a publication citation network. This article presents a descriptive statistic on loops in publication citation networks of computer science and physics by employing a network-based indicator, namely, strongly connected component (SCC). By employing computer science and physics disciplines publications from the Web of Science database as examples, this article examines the count of loops, how the count changes over time and how the count relates to the published year difference between publications within the loop in the citation network. Some common structural patterns are also extracted and analysed; we observe that the two disciplines share the most frequent patterns though there exist some minor differences. Moreover, we find that self-citations in terms of authors, authors’ institutions and journals contribute to the formation of loops in publication citation networks.

scholarly journals The Multi-Pattern Approach for Systematic Analysis of Transition Pathways

2019 ◽  
Vol 11 (2) ◽  
pp. 318 ◽  
Author(s):  
Fjalar De Haan ◽  
Briony Rogers
Keyword(s):  
Water Management ◽  
Functional System ◽  
Systematic Analysis ◽  
Pattern Approach ◽  
Transition Pathways ◽  
Central Notion ◽  
Case Comparison ◽  
High Level ◽  
Over Time

Pathways have become a central notion in various areas of research, amongst which are the studies of transitions to sustainability. Though various typologies and concepts are available, a framework for systematic analysis of transition pathways is lacking. We present the Multi-Pattern Approach (MPA) to fill this lacuna and provide a step-by-step manual for its application. The MPA addresses a range of traditional challenges of transitions’ pathway analysis, such as temporal and functional system demarcation and the unravelling of complex, interrelated systemic storylines. The approach provides an oft-called for rigour which allows a diagrammatic and formulaic representation of transitions’ pathways. Because of these qualities, the approach allows systematic cross-case comparison and provides a bridge between narrative-based and computational transitions research. The approach is demonstrated with an in-depth empirical case study of water management in Melbourne, Australia over the last 180 years. The article first presents a high-level mapping of the system’s evolution over time and a detailed analysis of the uptake and phasing out of specific servicing technologies and practices.

scholarly journals Green business cycle: an analysis on China and France

2020 ◽  
pp. 563-576
Keyword(s):  
Business Cycles ◽  
Business Cycle ◽  
Green Growth ◽  
Green Gdp ◽  
Green Business ◽  
Macroeconomic Indicators ◽  
Strongly Connected ◽  
High Degree ◽  
Degree Of Similarity ◽  
Over Time

Business cycle analysis generated an essential impulse in stimulating and provoking interesting academic and professional debates within a growth perspective. In fact, measuring business cycles is critical in determining the stylized facts on the cyclical behavior of aggregate macroeconomic indicators over time. As green growth topics started to occupy much academic interest, the question of the co-existence of equitable and sustainable development as well as current dynamics and cyclical features of economic growth comes into foreplay. This paper aims to evaluate cyclical characteristics of green growth related variables by observing two countries that showed different green policy aspirations over time, namely China and France. Following the paper's main objective, we want to provide a detailed analysis of the extent to which Green GDP and relevant output measures are comparable in a wider 'deviation cycle' context that includes cycle correlation, cycle coherence, and cycle magnitude. Results suggest that business cycles of GDP/GNI and Green GDP are strongly connected and coherent to a high degree. However, we found that the strength of that nexus and the degree of similarity has changed considerably over time, yet in a positive way.

scholarly journals Interpretative Polarization across Platforms: How Political Disagreement Develops Over Time on Facebook, Twitter, and WhatsApp

2020 ◽  
Vol 6 (3) ◽  
pp. 205630512094439
Author(s):  
Neta Kligler-Vilenchik ◽  
Christian Baden ◽  
Moran Yarchi
Keyword(s):  
Social Media ◽  
Present Article ◽  
Political Polarization ◽  
Theoretical Understanding ◽  
Political Issue ◽  
Media Environment ◽  
Political Controversy ◽  
Strongly Connected ◽  
Social Media Platforms ◽  
Over Time

Political polarization, seen as a key threat to contemporary democracy, has been tied to the rise of digital social media. However, how this process develops in the context of a social media environment characterized by multiple platforms—with differing norms, contents, and affordances—has not been sufficiently explored. In the present article, we propose a distinction between positional polarization, that is, people’s view on a political issue, and interpretative polarization, that is, how that political issue is contextualized and understood. We use this distinction to examine an issue of political controversy in Israel, examining how polarization develops over time, on three social media platforms—Facebook, Twitter, and WhatsApp. We find that contrasting positions are strongly connected to conflicting interpretations, both of which are clear from the start, with only minor overtime shifts. Moreover, while sharing broad similarities, the three platforms show a few distinctive polarization dynamics—both positional and interpretative—that can be connected to their varied socio-technical affordances. The study advances our theoretical understanding of polarization by examining how different social media platforms may shape distinct polarization dynamics over time, with different implications for democratic debate.

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