scholarly journals PreDarwinian evolution, prebiotic change: a principle of least selection

2021 ◽  
Author(s):  
Michael Yarus
Keyword(s):  
Natural Selection ◽  
Standard Deviation ◽  
Molecular Complex ◽  
Minimal Change ◽  
Materials Chemistry ◽  
Evolutionary Path ◽  
Proportionality Constant ◽  
Selection For ◽  
The Cost ◽  
Selection Of

Evolution prior to its Darwinian era was an age of variation. Events allowed by starting materials, chemistry and physics were realized, directed by intrinsic probabilities. In this landscape, a principle of least selection defines the most probable evolutionary path. For selection from a population where x varies, the rate of x evolution dx/dt = αΔμ. μ is the population mean of the selected property x, [alpha] a proportionality constant. Explicit equations for selected change Δμ are presented. Simple results exist for frequent cases; for example, selection for x ≥ a threshold. Maximizing Δμ minimizes need for selection. Least selections for x demand maximal selection dependence on x, maximal x standard deviation σ, and maximal lower x threshold (consistent with the need for a survivor). Least selection is free of the cost of natural selection, thus can support rapid advance. Least selection also unites previous seemingly independent optima. As examples, evolution via ′starting bloc selection [prime] and ′chance utility′ (where selection spans a minimal change) and ′near-ideal reactions′ (where variable reactant supplies create easy reactions) occur via transitory paths of least selection. ′Bayesian convergence′ is guaranteed by least selection′s extremum (which sharply defines evolution′s path). [prime]Distribution fitness′ (where specific outcomes are selected among multiple concurrent variations) is least selection of rare functional minorities. Inheritance of encoded chemical capabilities first evolves because templating and catalysis are close, potentially joined in a single molecular complex. Least selection defines directions, biostructures define destinations in likely pathways of preDarwinian evolution.

scholarly journals Selection for plasmid post–segregational killing depends on multiple infection: evidence for the selection of more virulent parasites through parasite–level competition

2005 ◽  
Vol 272 (1561) ◽  
pp. 403-410 ◽  
Author(s):  
T. F. Cooper ◽  
J. A. Heinemann
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Multiple Infection ◽  
Virulence Determinant ◽  
New Hosts ◽  
Parasite Reproduction ◽  
Selection For ◽  
The Cost ◽  
Selection Of

Is the virulence of parasites an outcome of optimized infection? Virulence has often been considered an inevitable consequence of parasite reproduction when the cost incurred by the parasite in reducing the fitness of its current host is offset by increased infection of new hosts. More recent models have focused on how competition occurring between parasites during co–infection might effect selection of virulence. For example, if co–infection was common, parasites with higher intrinsic growth rates might be selected, even at the expense of being optimally adapted to infect new hosts. If growth rate is positively correlated with virulence, then competition would select increased virulence. We tested these models using a plasmid–encoded virulence determinant. The virulence determinant did not contribute to the plasmid's reproduction within or between hosts. Despite this, virulent plasmids were more successful than avirulent derivatives during selection in an environment allowing within–host competition. To explain these findings we propose and test a model in which virulent parasites are selected by reducing the reproduction of competitors.

scholarly journals Selection for antibiotic resistance is reduced when embedded in a natural microbial community

2019 ◽  
Author(s):  
Uli Klümper ◽  
Mario Recker ◽  
Lihong Zhang ◽  
Xiaole Yin ◽  
Tong Zhang ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Microbial Community ◽  
Single Species ◽  
Natural Environments ◽  
Order Of Magnitude ◽  
Natural Microbial Community ◽  
Cost Of Resistance ◽  
Selection For ◽  
The Cost ◽  
Selection Of

AbstractAntibiotic resistance has emerged as one of the most pressing, global threats to public health. In single-species experiments selection for antibiotic resistance occurs at very low antibiotic concentrations. However, it is unclear how far these findings can be extrapolated to natural environments, where species are embedded within complex communities. We competed isogenic strains of Escherichia coli, differing exclusively in a single chromosomal resistance determinant, in the presence and absence of a pig fecal microbial community across a gradient of antibiotic concentration for two relevant antibiotics: gentamicin and kanamycin. We show that the minimal selective concentration was increased by more than one order of magnitude for both antibiotics when embedded in the community. We identified two general mechanisms were responsible for the increase in minimal selective concentration: an increase in the cost of resistance and a protective effect of the community for the susceptible phenotype. These findings have implications for our understanding of the evolution and selection of antibiotic resistance, and can inform future risk assessment efforts on antibiotic concentrations.

The natural selection of psychosis

2006 ◽  
Vol 29 (4) ◽  
pp. 410-411 ◽  
Author(s):  
Bernard Crespi
Keyword(s):  
Natural Selection ◽  
Mental Disorders ◽  
Evolutionary Biology ◽  
Secondary Effects ◽  
Strong Selection ◽  
Selection For ◽  
Selection Of

Diverse evidence from genomics, epidemiology, neurophysiology, psychology, and evolutionary biology converges on simple general mechanisms, based on negative secondary effects of strong selection, for how mental disorders such as psychosis have evolved and how they are sustained.

Limits to selection for disease resistance from natural tree populations

1993 ◽  
Vol 23 (9) ◽  
pp. 1944-1947 ◽  
Author(s):  
B.J. Van Der Kamp
Keyword(s):  
Disease Resistance ◽  
Natural Selection ◽  
Lodgepole Pine ◽  
Substantial Variation ◽  
Random Placement ◽  
Susceptibility Model ◽  
Selection For ◽  
Selection Of

It is demonstrated that for diseases characterized by a small number of discrete infections per tree, random placement of spores on trees results in substantial variation in the number of infections per tree. The consequences of this phenomenon for selection of resistant individuals and for natural selection are examined, using a previously reported distribution of susceptibility model for the western gall rust (Endocronartiumharknessii (J.P. Moore) Y. Hiratsuka)–lodgepole pine (Pinusconforta Dougl.) pathosystem as an example.

Identifying Measurement Invariant Item Sets in Cross-Cultural Settings Using an Automated Item Selection Procedure

Methodology ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 177-188 ◽  
Author(s):  
Martin Schultze ◽  
Michael Eid
Keyword(s):  
Measurement Invariance ◽  
Optimal Solution ◽  
Selection Procedure ◽  
Cross Cultural ◽  
Item Selection ◽  
Ant System ◽  
Item Quality ◽  
Ant System Algorithm ◽  
Selection For ◽  
Selection Of

Abstract. In the construction of scales intended for the use in cross-cultural studies, the selection of items needs to be guided not only by traditional criteria of item quality, but has to take information about the measurement invariance of the scale into account. We present an approach to automated item selection which depicts the process as a combinatorial optimization problem and aims at finding a scale which fulfils predefined target criteria – such as measurement invariance across cultures. The search for an optimal solution is performed using an adaptation of the [Formula: see text] Ant System algorithm. The approach is illustrated using an application to item selection for a personality scale assuming measurement invariance across multiple countries.

The Natural Selection of Minds

1998 ◽  
Vol 43 (4) ◽  
pp. 263-264
Author(s):  
Joseph F. Rychlak
Keyword(s):  
Natural Selection ◽  
Selection Of

ESTIMASI NILAI HERITABILITAS BOBOT IKAN MAS VARIETAS PUNTEN DALAM PROGRAM SELEKSI INDIVIDU

2016 ◽  
Vol 11 (3) ◽  
pp. 217
Author(s):  
Estu Nugroho ◽  
Budi Setyono ◽  
Mochammad Su’eb ◽  
Tri Heru Prihadi
Keyword(s):  
Body Weight ◽  
Selection Response ◽  
Base Population ◽  
Breeding Programs ◽  
Male And Female ◽  
Body Weight Trait ◽  
Population Selection ◽  
Selection For ◽  
Weight Trait ◽  
Selection Of

Program pemuliaan ikan mas varietas Punten dilakukan dengan seleksi individu terhadap karakter bobot ikan. Pembentukan populasi dasar untuk kegiatan seleksi dilakukan dengan memijahkan secara massal induk ikan mas yang terdiri atas 20 induk betina dan 21 induk jantan yang dikoleksi dari daerah Punten, Kepanjen (delapan betina dan enam jantan), Kediri (tujuh betina dan 12 jantan), Sragen (27 betina dan 10 jantan), dan Blitar (15 betina dan 11 jantan). Larva umur 10 hari dipelihara selama empat bulan. Selanjutnya dilakukan penjarangan sebesar 50% dan benih dipelihara selama 14 bulan untuk dilakukan seleksi dengan panduan hasil sampling 250 ekor individu setiap populasi. Seleksi terhadap calon induk dilakukan saat umur 18 bulan pada populasi jantan dan betina secara terpisah dengan memilih berdasarkan 10% bobot ikan yang terbaik. Calon induk yang terseleksi kemudian dipelihara hingga matang gonad, kemudian dipilih sebanyak 150 pasang dan dipijahkan secara massal. Didapatkan respons positif dari hasil seleksi berdasarkan bobot ikan, yaitu 49,89 g atau 3,66% (populasi ikan jantan) dan 168,47 g atau 11,43% (populasi ikan betina). Nilai heritabilitas untuk bobot ikan adalah 0,238 (jantan) dan 0,505 (betina).Punten carp breeding programs were carried out by individual selection for body weight trait. The base population for selection activities were conducted by mass breeding of parent consisted of 20 female and 21 male collected from area Punten, eight female and six male (Kepanjen), seven female and 12 male (Kediri), 27 female and 10 male (Sragen), 15 female and 11 male (Blitar). Larvae 10 days old reared for four moths. Then after spacing out 50% of total harvest, the offspring reared for 14 months for selection activity based on the sampling of 250 individual each population. Selection of broodstock candidates performed since 18 months age on male and female populations separately by selecting based on 10% of fish with best body weight. Candidates selected broodstocks were then maintained until mature. In oder to produce the next generation 150 pairs were sets and held for mass spawning. The results revealed that selection response were positive, 49.89 g (3.66%) for male and 168.47 (11.43%) for female. Heritability for body weight is 0.238 (male) and 0.505 (female).

Determination of the minimum number of technological bases of a part

2020 ◽  
pp. 73-75
Author(s):  
B.M. Bazrov ◽  
T.M. Gaynutdinov
Keyword(s):  
Cost Price ◽  
Labor Input ◽  
Part Surface ◽  
Technological Base ◽  
Size Accuracy ◽  
Minimum Number ◽  
The Cost ◽  
Input Cost ◽  
Selection Of

The selection of technological bases is considered before the choice of the type of billet and the development of the route of the technological process. A technique is proposed for selecting the minimum number of sets of technological bases according to the criterion of equality in the cost price of manufacturing the part according to the principle of unity and combination of bases at this stage. Keywords: part, surface, coordinating size, accuracy, design and technological base, labor input, cost price. [email protected]

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