scholarly journals Evolutionary coexistence in a fluctuating environment by specialization on resource level

2021 ◽  
Author(s):  
Meike T Wortel
Keyword(s):  
Species Level ◽  
Natural Environments ◽  
Yeast Saccharomyces Cerevisiae ◽  
Nutrient Levels ◽  
High Resource ◽  
Resource Level ◽  
Long Time ◽  
Single Strategy ◽  
Substrate Concentrations ◽  
Stable Outcome

Microbial communities in fluctuating environments can contain many species and diversity within species, both in natural environments such as the human gut, and in laboratory settings when communities are propagated for a long time. Whether this diversity is at the species level, within the species level, or a combination of both, the question remains: what processes lead to the origination and maintenance of this diversity? When nutrient levels fluctuate over time, one possibly relevant process is that different types specialize on low and high nutrient levels. The relevance of this process is supported by observations of types co-existing through this mechanism when put together in the laboratory, and simple models, which show that negative frequency dependence of two types, specialized on low and high resource level, can stabilize coexistence. However, when microbial populations are in an environment for a long time, they will evolve. In this article we determine what happens when species can evolve; whether branching can occur to create diversity and whether evolution will destabilize coexistence. We find that for the trade-off data between growth at low and high substrate concentrations, available for the bacterium Escherichia coli and the yeast Saccharomyces cerevisiae on glucose, there is only a small portion of the trait-space that allows for coexistence. Moreover, this coexistence is destabilized by evolution, and the only evolutionary stable outcome is a single strategy. When we combine two species that are well-adapted on their own, we do find that they can form an evolutionary singular coalition. We conclude that although specialization on resource level can support diversity within a species, it is likely not a cause by itself. In contrast, for species consortia this specialization can lead to evolutionary stable coexistence.

scholarly journals The resistome of common human pathogens

2017 ◽  
Author(s):  
Christian Munck ◽  
Mostafa M. Hashim Ellabaan ◽  
Michael Schantz Klausen ◽  
Morten O.A. Sommer
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Bacterial Pathogens ◽  
Antibiotic Resistance Genes ◽  
Gene Clusters ◽  
Species Level ◽  
Natural Environments ◽  
Human Pathogens ◽  
Bacterial Genomes ◽  
Risk Ranking

AbstractGenes capable of conferring resistance to clinically used antibiotics have been found in many different natural environments. However, a concise overview of the resistance genes found in common human bacterial pathogens is lacking, which complicates risk ranking of environmental reservoirs. Here, we present an analysis of potential antibiotic resistance genes in the 17 most common bacterial pathogens isolated from humans. We analyzed more than 20,000 bacterial genomes and defined a clinical resistome as the set of resistance genes found across these genomes. Using this database, we uncovered the co-occurrence frequencies of the resistance gene clusters within each species enabling identification of co-dissemination and co-selection patterns. The resistance genes identified in this study represent the subset of the environmental resistome that is clinically relevant and the dataset and approach provides a baseline for further investigations into the abundance of clinically relevant resistance genes across different environments. To facilitate an easy overview the data is presented at the species level at www.resistome.biosustain.dtu.dk.

The upper Paleozoic (Pennsylvanian-Permian) ammonoid Emilites

1988 ◽  
Vol 62 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Royal H. Mapes ◽  
Darwin R. Boardman
Keyword(s):  
Soviet Union ◽  
North America ◽  
Species Level ◽  
Time Range ◽  
Early Permian ◽  
Generic Level ◽  
The Soviet Union ◽  
Upper Paleozoic ◽  
Long Time ◽  
Permian Ammonoid

Four species of Emilites are now known; these are E. incertus (Böse), E. plummeri Ruzhencev, E. brownwoodi n. sp., and E. bennisoni n. sp. Representatives of this genus may occur as early as Middle Pennsylvanian in North America to as late as Early Permian in the Soviet Union. All described taxa are from North America except E. plummeri, which is from the Soviet Union. Because Emilites is extremely rare in upper Paleozoic ammonoid assemblages, generic and species level phylogenetic relationships are poorly understood. Emilites is not considered to be a good generic-level zone indicator due to its relatively long time range and its rarity.

A profound view and discourse on the typification and status of three confused taxa: Ruppia maritima, R. spiralis and R. cirrhosa

2020 ◽  
Vol 63 (3) ◽  
pp. 229-239 ◽  
Author(s):  
Cornelis den Hartog ◽  
Ludwig Triest
Keyword(s):  
Type Species ◽  
Historical Context ◽  
Species Level ◽  
Ruppia Maritima ◽  
Ruppia Cirrhosa ◽  
Long Time

AbstractTaxonomic difficulties have persisted within the genus Ruppia for a long time. We first unravel misconceptions as perceived on different continents and subsequently present a revised interpretation of the identity and typification of three European taxa at species level: Ruppia maritima L., Ruppia spiralis L. ex Dumortier, and Ruppia cirrhosa (Petagna) Grande. To do this, historical specimens, illustrations and original descriptions were studied. We supersede a previous choice of the figure of Buccaferrea maritima, foliis minus acutis Micheli (1729) as the lectotype of R. maritima and type species of the genus Ruppia owing to a serious conflict with the protologue. Based on a meticulous interpretation of protologues and figures in a historical context, we reject the recent view of assigning R. cirrhosa and its proposed lectotype (iconotype) as a homotypic synonym of R. maritima. We agree with an earlier lectotypification of R. spiralis, though for another reason than the above-mentioned abused homotypy. Consequently, R. cirrhosa is a synonym of neither R. maritima or R. spiralis, based on material from Petagna in the Herbarium of Naples designated as the holotype of R. cirrhosa. We argue for three species to be considered as fully independent taxa: R. maritima, R. spiralis and R. cirrhosa.

scholarly journals Buildings and constructions on the base of timber for the Arctic regions

2019 ◽  
Vol 110 ◽  
pp. 01089
Author(s):  
Ivan Inzhutov ◽  
Victor Zhadanov ◽  
Peter Melnikov ◽  
Sergei Amelchugov ◽  
Irina Melnikova
Keyword(s):  
High Latitude ◽  
Vertical Axis ◽  
The Arctic ◽  
Specific Strength ◽  
High Resource ◽  
Reuleaux Triangle ◽  
Technological Chain ◽  
Northern Regions ◽  
Long Time ◽  
Extreme North

Economic efficiency of development of high-latitude territories directly depends on the construction technologies applied here. Traditional materials such as reinforced concrete and steel cause unacceptably high resource consumption throughout the entire technological chain of construction production in the Northern regions, and the mechanical transfer of construction technologies to high-latitude construction are ineffective. Analysis of environmental effects on buildings and structures has shown that the most effective for the Extreme North is the dome shape, namely: the building of the lenticular shape; dome building; the building in the form of a sphere; in the form of a cone formed by rotating the Reuleaux triangle around the vertical axis of symmetry; the building of tetrahedron type, and various shapes formed by the combination of buildings of dome shapes. The rationality of constructions made of wood and wood materials is emphasized, which determines the necessity of creating an industry of glued elements. It has been widely used in high-latitude construction and has proved to be the best in terms of frost resistance, low resistance to corrosion from blizzards, high specific strength and low thermal conductivity for a long time.

Buffer Managed Multiple Replication Strategy Using Knapsack Policy for Intermittently Connected Mobile Networks

2014 ◽  
pp. 1-22
Author(s):  
C. Poongodi ◽  
A. M. Natarajan
Keyword(s):  
Mobile Networks ◽  
Relay Node ◽  
Resource Consumption ◽  
Delivery Ratio ◽  
Global Knowledge ◽  
High Resource ◽  
Replication Strategy ◽  
Long Time ◽  
Network Overhead ◽  
Intermittently Connected

Intermittently Connected Mobile Networks (ICMNs) are a kind of wireless network where, due to mobility of nodes and lack of connectivity, there may be disconnections among the nodes for a long time. To deal with such networks, store-carry-forward method is adopted for routing. This method buffers the messages in each node for a long time until a forwarding opportunity comes. Multiple replications are made for each message. It results in an increase in network overhead and high resource consumption because of uncontrolled replications. Uncontrolled replications are done due to lack of global knowledge about the messages and the forwarding nodes. The authors introduce a new simple scheme that applies knapsack policy-based replication strategy while replicating the messages residing in a node buffer. The numbers of replications are controlled by appropriately selecting messages based on the total count on replications already made and the message size. In addition, the messages are selected for forwarding based on the relay node goodness in contacting the destination and the remaining buffer size of that relay node. Therefore, useful replications are made based on the dynamic environment of a network, and it reduces the network overhead, resource consumption, delivery delay, and in turn, increases the delivery ratio.

Poecilimon bosphoricus group (Orthoptera, Phaneropterinae): iteration of morpho-taxonomy by song characteristics

Zootaxa ◽  
2012 ◽  
Vol 3225 (1) ◽  
pp. 1 ◽  
Author(s):  
SARP KAYA ◽  
BATTAL ÇIPLAK ◽  
DRAGAN CHOBANOV ◽  
KLAUS-GERHARD HELLER
Keyword(s):  
New Species ◽  
Species Level ◽  
Subgenital Plate ◽  
Long Time ◽  
Male Calling ◽  
Productive Structure ◽  
Definition Of ◽  
Caudal Margin

More than 20 species were reported under the circum Black Sea lineage Poecilimon bosphoricus group (Orthoptera, Tet-tigonioidea, Phaneropterinae). The taxonomy of the group has for a long time been controversial; once these species weretransferred to Eupoecilimon and many new species have been described since the revision by Ramme (1933) or synonymshave been suggested/re-established. This study aims to test the classification of the group presently based on morpholog-ical characters by bioacoustic data. The following results were obtained or conclusions arrived. First, several qualitativemorphological characters previously used in descriptions/diagnoses of the species are variable and overlap between spe-cies. Those are the elevation and widening of pronotum in metazona, the emargination of caudal margin of pronotal discand the structure of male subgenital plate at caudal margin. Thus, still the male cercus, especially the orientation of den-ticles, is the most productive structure may allow more objective delimitation of species. As in qualitative morphology thegeneral morphometry seems uninformative for the taxonomy of the group. Second, male calling song and partly the num-ber of stridulatory pegs are more useful characters both for delimitation of species and describing their relationships. Es-pecially, the pattern of the syllable, the number of impulses per syllable and the duration of early part of syllable in speciesgroup allow us a more objective delimitation of the species and definition of relationships. Third, from the distributionand relationships of species, we suggested three radiation centres for the lineage: (1) Northwest Anatolia + Eastern Bal-kans, (2) Northeast Anatolia + Caucasus and (3) Crimea. Fourth, after evaluating morphological and song phenotypes we considered 21 species in P. bosphoricus group constituting three subgroups: (1) P. sureyanus and P. kocaki (+ P. athos),(2) P. turcicus + P. turciae and (3) P. bidens, P. bischoffi, P. bosphoricus, P. cervus, P. demirsoyi, P. geoktschajcus, P. hei-nrichi, P. istanbul, P. miramae, P. pliginskii, P. proximus, P. roseoviridis sp. n., P. scythicus, P. similis and P. tauricus (+ P.djakonovi). The following nomenclatural actions were made: (1) P. roseoviridis Chobanov & Kaya sp. n. described, (2)P. similis proximus Ünal, 2010 raised to species level as P. proximus stat. n., (3) P. naskrecki Ünal, 2001 syn.n. syn-onymised with P. demirsoyi Sevgili, 2001 (4) P. diversus Ünal, 2010 syn.n. and P. anatolicus Ramme 1933 syn.n. put insynonymy with P. sureyanus Uvarov, 1930, (5) P. oligacanthus Miram, 1938 syn.n. and P. tereckensis Stshelkanovtzev,1910 stat.rev. resynonymised with P. similis Retowski, 1889, (6) P. beybienkoi Tarbinsky, 1932 syn.n. and P. kusnezoviMiram, 1929 syn.n. synonymised with P. tauricus Retwoski, 1888, and (7) P. boldyrevi Miram, 1938 syn.n. synonymised with P. pliginskii Miram, 1929.

scholarly journals Edaphic mesostigmatid mites (Parasitiformes, Mesostigmata) in a region of the Pampa biome of the state of Rio Grande do Sul, Brazil

2020 ◽  
Vol 50 (2) ◽  
Author(s):  
Adriane da Fonseca Duarte ◽  
Grazielle Furtado Moreira ◽  
Uemerson Silva da Cunha ◽  
Paulo Ricardo Ebert Siqueira ◽  
Gilberto José de Moraes
Keyword(s):  
Rio Grande ◽  
Single Species ◽  
Abundant Species ◽  
Soil Samples ◽  
The State ◽  
Species Level ◽  
Natural Environments ◽  
Rio Grande Do Sul ◽  
Pampa Biome ◽  
Potential Use

ABSTRACT: The diversity of edaphic mites in Brazilian natural environments is little known, especially in the Pampa biome, in southern region of Brazil. The objective of this study was to evaluate the diversity and abundance of edaphic fauna of mesostigmatid mites in a region of the Pampa biome of the state of Rio Grande do Sul. Soil samples were collected in the municipality of Aceguá, in 2012 and 2013. Mites were extracted using Berlese-Tullgren modified funnels. In total, 1900 mesostigmatid mites were collected, representing 44 species from 23 genera and 10 families. The most abundant families were Rhodacaridae, Ologamasidae and Laelapidae, with respectively 903, 578 and 214 specimens, corresponding respectively to 47.5, 30.4 and 11.3% of the Mesostigmata collected. Laelapidae was the most diverse family, being represented by 22 species. The remaining families were each represented by 1-5 species. Gaeolaelaps (Laelapidae) was the most diverse genus, with 14 species. Rhodacaridae was represented by a single species, Binodacarus aceguaensis Duarte, Castilho, Cunha & Moraes, representing 47.5% of the mesostigmatids. Ologamasidae was represented by four species, with Neogamasellevans sp. corresponding to the second most abundant species, representing 27.5% of the mesostigmatids. Further analysis of the data, in terms of mite identification to species level and the potential use of the mites collected for applied biological control are needed.

scholarly journals Automatic word count estimation from daylong child-centered recordings in various language environments using language-independent syllabification of speech

2019 ◽  
Author(s):  
Okko Räsänen ◽  
Shreyas Seshadri ◽  
julien karadayi ◽  
Eric Riebling ◽  
John P Bunce ◽  
...  
Keyword(s):  
Training Data ◽  
Natural Environments ◽  
Word Count ◽  
High Resource ◽  
Current State ◽  
Quality Signals ◽  
Child Centered ◽  
Acoustic Environments ◽  
Different Cultures ◽  
Count Estimation

Automatic word count estimation (WCE) from audio recordings can be used to quantify the amount of verbal communication in a recording environment. One key application of WCE is to measure language input heard by infants and toddlers in their natural environments, as captured by daylong recordings from microphones worn by the infants. Although WCE is nearly trivial for high-quality signals in high-resource languages, daylong recordings are substantially more challenging due to the unconstrained acoustic environments and the presence of near- and far-field speech. Moreover, many use cases of interest involve languages for which reliable ASR systems or even well-defined lexicons are not available. A good WCE system should also perform similarly for low- and high-resource languages in order to enable unbiased comparisons across different cultures and environments. Unfortunately, the current state-of- the-art solution, the LENA system, is based on proprietary software and has only been optimized for American English, limiting its applicability. In this paper, we build on existing work on WCE and present the steps we have taken towards a freely available system for WCE that can be adapted to different languages or dialects with a limited amount of orthographically transcribed speech data. Our system is based on language-independent syllabification of speech, followed by a language-dependent mapping from syllable counts (and a number of other acoustic features) to the corresponding word count estimates. We evaluate our system on samples from daylong infant recordings from six different corpora consisting of several languages and socioeconomic environments, all manually annotated with the same protocol to allow direct comparison. We compare a number of alternative techniques for the two key components in our system: speech activity detection and automatic syllabification of speech. As a result, we show that our system can reach relatively consistent WCE accuracy across multiple corpora and languages (with some limitations). In addition, the system outperforms LENA on three of the four corpora consisting of different varieties of English. We also demonstrate how an automatic neural network-based syllabifier, when trained on multiple languages, generalizes well to novel languages beyond the training data, outperforming two previously proposed unsupervised syllabifiers as a feature extractor for WCE.

Numerical taxonomy of fenestrate bryozoans: evaluation of methodologies and recognition of intraspecific variation

1994 ◽  
Vol 68 (6) ◽  
pp. 1201-1214 ◽  
Author(s):  
E. J. Holdener
Keyword(s):  
Intraspecific Variation ◽  
Depositional Environments ◽  
Species Level ◽  
Morphologic Change ◽  
Data Sets ◽  
Mississippi Valley ◽  
Time Intervals ◽  
East Central ◽  
Starting Point ◽  
Long Time

Species-level taxonomy of fenestrate cryptostome bryozoans has been greatly advanced by a recent study of the fenestrate fauna of the Warsaw Formation (Osage–Meramecian) of the Mississippi Valley; subsequent quantitative analysis placed the earlier research on a sound statistical basis. Reproducibility of these results is tested here, and it is demonstrated that subsequent researchers can duplicate earlier data collection and results. The methodology is then extended in space and time to a second fenestrate faunule (Virgilian of east-central Kansas); morphs within two traditionally defined fenestrate species are successfully distinguished.Lithologic characteristics of the two Virgilian study units suggest differences in depositional environments between the horizons and therefore simple ecophenotypy and intraspecific variation cannot be dismissed. However, chamber dimensions, which provide the most sensitive characters for taxonomic discrimination, change in parallel for the two species, whereas exterior skeletal dimensions, which would presumably respond more readily to microenvironmental fluctuations, vary nonsystematically between populations. These results provide a starting point for the evaluation of morphologic change within fenestrates through stratigraphic and paleoenvironmental sequences. Cumulative data sets spanning long time intervals would allow evaluations of evolutionary histories among members of this important Paleozoic clade.

scholarly journals Evolutionary dynamics of competing phenotype-structured populations in periodically fluctuating environments

2019 ◽  
Vol 80 (3) ◽  
pp. 775-807 ◽  
Author(s):  
Aleksandra Ardaševa ◽  
Robert A. Gatenby ◽  
Alexander R. A. Anderson ◽  
Helen M. Byrne ◽  
Philip K. Maini ◽  
...  
Keyword(s):  
Cancer Metabolism ◽  
Evolutionary Dynamics ◽  
Continuous Variable ◽  
Structured Populations ◽  
Nutrient Level ◽  
Nutrient Levels ◽  
Fluctuating Environments ◽  
Long Time ◽  
Phenotypic Variations ◽  
Varying Environments

Abstract Living species, ranging from bacteria to animals, exist in environmental conditions that exhibit spatial and temporal heterogeneity which requires them to adapt. Risk-spreading through spontaneous phenotypic variations is a known concept in ecology, which is used to explain how species may survive when faced with the evolutionary risks associated with temporally varying environments. In order to support a deeper understanding of the adaptive role of spontaneous phenotypic variations in fluctuating environments, we consider a system of non-local partial differential equations modelling the evolutionary dynamics of two competing phenotype-structured populations in the presence of periodically oscillating nutrient levels. The two populations undergo heritable, spontaneous phenotypic variations at different rates. The phenotypic state of each individual is represented by a continuous variable, and the phenotypic landscape of the populations evolves in time due to variations in the nutrient level. Exploiting the analytical tractability of our model, we study the long-time behaviour of the solutions to obtain a detailed mathematical depiction of the evolutionary dynamics. The results suggest that when nutrient levels undergo small and slow oscillations, it is evolutionarily more convenient to rarely undergo spontaneous phenotypic variations. Conversely, under relatively large and fast periodic oscillations in the nutrient levels, which bring about alternating cycles of starvation and nutrient abundance, higher rates of spontaneous phenotypic variations confer a competitive advantage. We discuss the implications of our results in the context of cancer metabolism.

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