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1

The quantitative study of sexual and natural selection in the wild and in the laboratory  

Microsoft Academic Search

\\u000a I discuss the continuum of approaches that exist when studying sexual or natural selection in the wild and the laboratory.\\u000a These range from behavioural observations in the laboratory, via experimental manipulations of particular traits or environments,\\u000a to phenomenological studies in nature. I focus on the study of body size and related life history traits, particularly drawing\\u000a from our own studies

WOLF BLANCKENHORN

2

Natural Selection  

Microsoft Academic Search

IN NATURE of June 8 there appears a letter from my friend Prof. Poulton in which he replies to my statement that `natural selection' affords no explanation of evolution. He quotes in extenso a letter from Darwin to the distinguished American botanist Asa Gray, in which Darwin endeavours to deal with the objection that natural selection is a truism and

E. W. MacBride

1929-01-01

3

natural selection  

NSDL National Science Digital Library

Charles Darwin's theory of natural selection was the first plausible mechanism to explain the change of species over time, however, in it's original form it did not explain how new traits could form, or how traits that had formed could be passed on to successive generations. The rise in modern genetics helped to modify biologists understanding of evolution by attributing the origin of new traits in a species to random genetic processes of mutation and sexual recombination, with the survivability of species with the new traits subject to natural selection. This combination of random mutation and natural selection is often referred to as Neodarwinism.

David Joiner

4

Natural Selection  

Microsoft Academic Search

IN NATURE for November 21, there appears a letter from Prof. E. W. MacBride in which he attempts to demonstrate that natural selection is not an agent in the evolution of mimetic resemblances. It is perhaps open to question how far statements of personal opinion on evolutionary mechanisms are worth making or answering, unless they are sufficiently detailed to include

E. B. Ford

1936-01-01

5

Natural Selection  

NSDL National Science Digital Library

Learners simulate the process of natural selection using a variety of beans and a bowl with a hole cut into it. The variety of beans represents the variation in a population of microbes, and the bowl with a hole represents an antibiotic or some other selective pressure on the population. Only the beans that survive (don't fall through the hole) are allowed to reproduce for the next generation. Learners record and plot the number of each kind of bean through multiple generations. This activity also addresses the process of scientific investigation as learners are encouraged to design their own method of experimentation, make a hypothesis, record data, and share their results.

Thiel-Cobbey, Heather

2012-01-01

6

Natural Selection  

NSDL National Science Digital Library

A common criticism of natural selection is: How can it produce novel complex useful structures by pure random chance? Darwin argued that selection is not a random process, and furthermore, it is cumulative. This lesson provides a way for students to actually compare the cumulative non-random selection of Darwin with the non-cumulative version so often erroneously implied. Students attempt to produce a full sequence of 13 cards of one suit (ace - to king). This must be done by shuffling the suit of cards for each round, then checking the cards. Half the teams must look for the full sequence each time, and repeat the process until this is accomplished. The other teams start to build their sequence by pulling the ace when it first appears as the top card, then adding to the stack whenever the next card for the sequence is shuffled to the top. Discussion reveals how the second method mimics Darwinian natural selection, while the first does not.

Heim, Werner

2007-12-12

7

A Natural Selection  

NSDL National Science Digital Library

The high school science laboratory provides a natural environment for students to learn through scientist-teacher partnerships. A dynamic learning community, authentic inquiry, a deeper understanding of the nature of science, and learning about scientific careers are all benefits of scientist-teacher partnerships. This article focuses on the benefits of partnerships while describing how one specific partnership team developed a natural selection laboratory to integrate with a high school biology curriculum.

Nielsen, Katherine M.; Siegel, Marcelle A.; Mlynarczyk-Evans, Susanna; Brenner, Tamara J.

2005-10-01

8

Adaptive Value of Phenological Traits in Stressful Environments: Predictions Based on Seed Production and Laboratory Natural Selection  

PubMed Central

Phenological traits often show variation within and among natural populations of annual plants. Nevertheless, the adaptive value of post-anthesis traits is seldom tested. In this study, we estimated the adaptive values of pre- and post-anthesis traits in two stressful environments (water stress and interspecific competition), using the selfing annual species Arabidopsis thaliana. By estimating seed production and by performing laboratory natural selection (LNS), we assessed the strength and nature (directional, disruptive and stabilizing) of selection acting on phenological traits in A. thaliana under the two tested stress conditions, each with four intensities. Both the type of stress and its intensity affected the strength and nature of selection, as did genetic constraints among phenological traits. Under water stress, both experimental approaches demonstrated directional selection for a shorter life cycle, although bolting time imposes a genetic constraint on the length of the interval between bolting and anthesis. Under interspecific competition, results from the two experimental approaches showed discrepancies. Estimation of seed production predicted directional selection toward early pre-anthesis traits and long post-anthesis periods. In contrast, the LNS approach suggested neutrality for all phenological traits. This study opens questions on adaptation in complex natural environment where many selective pressures act simultaneously. PMID:22403624

Glorieux, Cédric; Cuguen, Joel; Roux, Fabrice

2012-01-01

9

Natural Selection and Natural Theology  

Microsoft Academic Search

A PERUSAL of Dr. Romanes' article on Natural Selection and Natural Theology, in the Contemporary Review for October, 1882, suggests a few remarks upon one or two points, which may not be out of place.

Asa Gray

1883-01-01

10

Natural Selection and Natural Theology  

Microsoft Academic Search

THE letter of Prof. Asa Gray (NATURE, vol. xxvii. p. 291) contains a sentence which seems to me to contain the essence of the difference between the views of organic life, as held by the supporters of Natural Selection and Natural Theology. He says: ``How is this presumption negatived or impaired by the supposition of Darwin's theory, that the ancestors

J. B. Hannay

1883-01-01

11

Visualizingandquantifying natural selection  

E-print Network

REVIEWS Visualizingandquantifying natural selection Edmund D. Brodie III, Allen 1. Moore. A thorough comprehen- sion of the occurrence, form and significance of selection in natural populations of current evolu- tionary research is the detection, demonstration and description of selection in nature

Brodie III, Edmund D.

12

Evolution by Natural Selection  

NSDL National Science Digital Library

Principles of natural selection are demonstrated by a simulation that involves different color pom-poms and student feeders equipped with different types of feeding implements. Students analyze results to see how different traits contribute to fitness in different habitats. Additional examples and questions help students to understand the process of natural selection, including three necessary conditions for natural selection to take place.

Doherty, Jennifer; Waldron, Ingrid

13

Natural Resource Ecology Laboratory  

NSDL National Science Digital Library

The Natural Resource Ecology Laboratory (NREL) at Colorado State University conducts multi-disciplinary research in ecosystem science, with the purpose of improving knowledge of "the complex interactions between humans, management activities, and ecosystems." The recently launched homepage, which is still under construction, includes background information on NREL; descriptions of research projects (a substantial and diverse list); publications, reports, and data; teaching and outreach; and contact information.

14

Natural Selection Lesson  

NSDL National Science Digital Library

The Natural Selection lesson uses a Monte Carlo model of spot size with variability between generations in an environment with predators to study how variation and environment can affect a species over time.

David Joiner

15

What is natural selection?  

Microsoft Academic Search

Natural selection’ is, it seems, an ambiguous term. It is sometimes held to denote a consequence of variation, heredity,\\u000a and environment, while at other times as denoting a force that creates adaptations. I argue that the latter, the force interpretation,\\u000a is a redundant notion of natural selection. I will point to difficulties in making sense of this linguistic practise, and

Björn Brunnander

2007-01-01

16

Lamarck and Natural Selection  

NSDL National Science Digital Library

Charles Darwin defined natural selection in "On the Origin of Species," however, Darwin did not invent the idea of evolution and not everyone saw his ideas as original. The shadow of Lamarckian theory which Darwin wanted desperately to escape is a genuine scientific precursor and what has become known as the Lamarckian Heresy has maintained a presence on the fringes of biology to this day. This radio broadcast explores who Lamarck was, how natural selection escaped from his shadow and gained acceptance from the scientific establishment, and whether any evidence has emerged that might challenge the elegant simplicity of natural selection. There is discussion about whether what is passed on to descendants may be affected by experience and environment; the experiments performed by Mendel that led to genetics; the role of DNA, gene mutations, and networks of genes in epigenetics; and how there seem to be fewer genes in humans than expected. The 2003 broadcast is 57 minutes in length.

17

Logic and Natural Selection  

Microsoft Academic Search

Is logic, feasibly, a product of natural selection? In this paper we treat this question as dependent upon the prior question\\u000a of where logic is founded. After excluding other possibilities, we conclude that logic resides in our language, in the shape\\u000a of inferential rules governing the logical vocabulary of the language. This means that knowledge of (the laws of) logic

Jaroslav Peregrin

2010-01-01

18

Naturally selecting solutions  

PubMed Central

For decades, computer scientists have looked to nature for biologically inspired solutions to computational problems; ranging from robotic control to scheduling optimization. Paradoxically, as we move deeper into the post-genomics era, the reverse is occurring, as biologists and bioinformaticians look to computational techniques, to solve a variety of biological problems. One of the most common biologically inspired techniques are genetic algorithms (GAs), which take the Darwinian concept of natural selection as the driving force behind systems for solving real world problems, including those in the bioinformatics domain. Herein, we provide an overview of genetic algorithms and survey some of the most recent applications of this approach to bioinformatics based problems. PMID:23222169

Manning, Timmy; Sleator, Roy D; Walsh, Paul

2013-01-01

19

Extending cosmological natural selection  

E-print Network

The purpose of this paper is to propose an extension to Lee Smolin's hypothesis that our own universe belongs to a population of universes evolving by natural selection. Smolin's hypothesis explains why the parameters of physics possess the values we observe them to possess, but depends upon the contingent fact that the universe is a quantum relativistic universe. It is proposed that the prior existence of a quantum relativistic universe can itself be explained by postulating that a process of cosmogenic drift evolves universes towards stable ('rigid') mathematical structures.

Gordon McCabe

2009-08-31

20

Natural Selection Simulation  

NSDL National Science Digital Library

This classroom activity introduces the concept of natural selection and how it relates to evolution. Students will use a variety of utensils including clothespins, tweezers and spoons to mimic animals with differently shaped mouths. The class will go through several trials, picking up at least twenty beans in one minute with their assigned utensil. If they fail to do so, their creature has died, demonstrating what happens to animals that cannot compete in the wild. Several discussion questions are included along with the activity.

2012-05-29

21

Natural Selection and Natural Theology  

Microsoft Academic Search

I READ with interest, in NATURE, vol. xxvii. p. 362, the reply made by Dr. Romanes to a letter of mine which, although not originally addressed to a scientific organ, found hospitable reception in your columns. It w as not much out of place there, for it was essentially an inquiry whether certain infesences may or may not scientifically be

Asa Gray

1883-01-01

22

Natural Selection and Natural Theology  

Microsoft Academic Search

THE amicable discussion between Dr. Romanes and myself, ``endeavouring to help in determining the true position of an important question,'' has now (in NATURE, vol. xxvii. p. 527) reached a critical point, one seemingly capable of settlement by scientific inquiry, and upon which a brief note may be pertinent.

Asa Gray

1883-01-01

23

Natural Selection and Natural Theology  

Microsoft Academic Search

I AM very glad to find from Prof. Asa Gray's last communication (NATURE, vol. xxviii. p. 78) that the result of our ``amicable discussion'' has been that of coming to an agreement on all points save one, which, as he truly observes, is ``seemingly capable of settlement by scientific inquiry.'' This point simply is as to whether variation in plants

George J. Romanes

1883-01-01

24

Natural Selection and Geology 230  

E-print Network

;Natural Selection · The theory of natural selection was proposed by Charles Darwin in 1859, in his bookNatural Selection and Evolution Geology 230 Fossils and Evolution #12;The Study of Evolution the same theory as Darwin in the 1850s. #12;One of the most famous and influential books of science. #12

Kammer, Thomas

25

Molecular Signatures of Natural Selection  

E-print Network

Molecular Signatures of Natural Selection Rasmus Nielsen Center for Bioinformatics and Department There is an increasing interest in detecting genes, or genomic re- gions, that have been targeted by natural selection contribution of natural selection in shaping the genetic variation observed among living organisms. In one

Nielsen, Rasmus

26

Natural selection maximizes Fisher information  

Microsoft Academic Search

In biology, information flows from the environment to the genome by the\\u000aprocess of natural selection. But it has not been clear precisely what sort of\\u000ainformation metric properly describes natural selection. Here, I show that\\u000aFisher information arises as the intrinsic metric of natural selection and\\u000aevolutionary dynamics. Maximizing the amount of Fisher information about the\\u000aenvironment captured by

Steven A. Frank

2009-01-01

27

Visualizing and quantifying natural selection  

Microsoft Academic Search

Modern methods of analysis are enabling researchers to study natural selection at a new level of detail. Multivariate statistical techniques can Identify specific targets of selection and provide parameter estimates that fit into equations for evolutionary change. A more Intuitive understanding of the form of selection can be provided through graphical representation of selection surfaces. Combinations of quantitative and visual

Edmund D. Brodie; Allen J. Moore; Fredric J. Janzen

1995-01-01

28

Darwin's Second Idea Natural Selection  

E-print Network

Darwin's Second Idea ­ Natural Selection · Evolution: controversial? · Natural selection ­ Darwin's postulates ­ Controversial? ­ Two examples of NS #12;Charles Darwin Darwin's Ideas 1. Species evolve over time: "descent with modification" Pattern #12;Charles Darwin Darwin's Ideas 1. Species evolve over time

29

Investigating Natural Selection: Elementary School  

NSDL National Science Digital Library

This lesson plan is designed for fourth and fifth grade students learning about natural selection. The class will investigate the predator-prey relationship as an example of how natural selection occurs in a population. Students will work in groups of three or four and observe how predators select their prey, and how this affects the subsequent populations of a species. The concept of camouflage is also covered in the material. This lesson is designed to take about sixty minutes of class time.

2010-01-01

30

On cosmic natural selection  

E-print Network

The rate of black hole formation can be increased by increasing the value of the cosmological constant. This falsifies Smolin's conjecture that the values of all constants of nature are adjusted to maximize black hole production.

Alexander Vilenkin

2006-11-27

31

Modeling Natural Selection  

NSDL National Science Digital Library

In their research, scientists generate, test, and modify scientific models. These models can be shared with others and demonstrate a scientist's understanding of how the natural world works. Similarly, students can generate and modify models to gain a bet

Lotter, Christine; Bogiages, Christopher A.

2011-02-01

32

Genetic Algorithms: Artificial Selection vs Natural Selection  

Microsoft Academic Search

Genetic Algorithms (GAs) are a stochastic searching and optimizing method inspired by the biological mechanism of natural selection and evolution. To improve the searching power of GAs for complicated problems, many deterministic measures, particularly, experience and\\/or expert knowledge-based heuristic rules, have been studied in the existing literature. This paper proposes a potentially more useful general methodology of integrating deterministic strategy

Xiao-Bing Hu; Ezequiel Di Paolo

33

Charles Darwin II: Natural selection  

NSDL National Science Digital Library

This is the second in a series of modules which detail the research of Charles Darwin and evolutionary theory. This module continues with a discussion of the processes that led to Darwin's formulation of the theory of natural selection.

Alfred Rosenberger

2004-02-12

34

MOLECULAR SIGNATURES OF NATURAL SELECTION  

Microsoft Academic Search

There is an increasing interest in detecting genes, or genomic re- gions, that have been targeted by natural selection. The interest stems from a basic desire to learn more about evolutionary pro- cesses in humans and other organisms, and from the realization that inferences regarding selection may provide important functional in- formation. This review provides a nonmathematical description of the

Rasmus Nielsen

2005-01-01

35

The cost of natural selection  

Microsoft Academic Search

Summary  Unless selection is very intense, the number of deaths needed to secure the substitution, by natural selection, of one gene\\u000a for another at a locus, is independent of the intensity of selection. It is often about 30 times the number of organisms in\\u000a a generation. It is suggested that, in horotelic evolution, the mean time taken for each gene substitution

J. B. S. Haldane

1957-01-01

36

Laboratory Selection Quickly Erases Historical Differentiation  

PubMed Central

The roles of history, chance and selection have long been debated in evolutionary biology. Though uniform selection is expected to lead to convergent evolution between populations, contrasting histories and chance events might prevent them from attaining the same adaptive state, rendering evolution somewhat unpredictable. The predictability of evolution has been supported by several studies documenting repeatable adaptive radiations and convergence in both nature and laboratory. However, other studies suggest divergence among populations adapting to the same environment. Despite the relevance of this issue, empirical data is lacking for real-time adaptation of sexual populations with deeply divergent histories and ample standing genetic variation across fitness-related traits. Here we analyse the real-time evolutionary dynamics of Drosophila subobscura populations, previously differentiated along the European cline, when colonizing a new common environment. By analysing several life-history, physiological and morphological traits, we show that populations quickly converge to the same adaptive state through different evolutionary paths. In contrast with other studies, all analysed traits fully converged regardless of their association with fitness. Selection was able to erase the signature of history in highly differentiated populations after just a short number of generations, leading to consistent patterns of convergent evolution. PMID:24788553

Lopes-Cunha, Miguel; Lima, Margarida; Kellen, Bárbara; Bárbaro, Margarida; Santos, Josiane; Rose, Michael R.; Santos, Mauro; Matos, Margarida

2014-01-01

37

Natural Selection in the Brain  

Microsoft Academic Search

\\u000a This chapter explores the possibility that natural selection takes place in the brain. We review the theoretical and experimental\\u000a evidence for selectionist and competitive dynamics within the brain. We propose that in order to explain human problem-solving,\\u000a selectionist mechanisms demand extension to encompass the full Darwinian dynamic that arises from introducing replication\\u000a of neuronal units of selection. The algorithmic advantages

Chrisantha Fernando; Eörs Szathmáry

38

Natural selection of visual symmetries  

Microsoft Academic Search

Implicitly, Wynn's target article starts from the transformational definition of symmetry. Unlike his suggestion, this traditional definition and the recent holographic definition are relevant to the discussion on the cognitive evolution of visual symmetries. These definitions reveal underlying properties and, thereby, they support the natural selection hypothesis. The holographic definition even agrees with an indirect test of this hypothesis

Peter A. van der Helm

2002-01-01

39

Darwin's Finches and Natural Selection  

NSDL National Science Digital Library

In this "clicker case," students learn about natural selection through the research of Peter and Rosemary Grant and colleagues on the finches of the Galapagos Islands. Students are presented with data in the form of graphs and asked to determine what is happening to a population of finches as the changing environment produces changes in the shape of the finches' beaks. This case is suitable for any size course in introductory biology, ecology, or evolution, and does not require any pre-requisite knowledge of evolution or natural selection. The case consists of a PowerPoint presentation (~4.5MB) punctuated by questions that students answer in class using "clickers." It can be adapted for use without these technologies.

Cheryl A. Heinz

2008-01-01

40

Natural selection in a contemporary human population  

E-print Network

Natural selection in a contemporary human population Sean G. Byarsa , Douglas Ewbankb , Diddahally for review June 25, 2009) Our aims were to demonstrate that natural selection is operating on contemporary and Boston Univer- sity that began in 1948. We found that natural selection is acting to cause slow, gradual

41

Natural selection and population Ilik Saccheri1  

E-print Network

Natural selection and population dynamics Ilik Saccheri1 and Ilkka Hanski2 1 School of Biological by concurrent natural selection? Density dependence and environmental stochasticity are generally expected a mechanism involving natural selection to explain population cycles in field voles Microtus agrestis ([1

Trexler, Joel C.

42

Non-random Allelic Variation Natural Selection  

E-print Network

Non-random Allelic Variation AKA Natural Selection #12;Adaptation!Adaptation! #12;#12;Venus comb or ­ a feature that is maintained because of natural selection for its function preadaptation ­ a trait history #12;Natural Selection Evolution evolution is a two step process 1) origin of genetic variation 2

Houde, Peter

43

Lab 2: Natural selection Basic instructions  

E-print Network

Lab 2: Natural selection Basic instructions: The module of Populus that we will be using in today's lab is `Selection on a diallelic locus.' To get to this module, click on `model' then on `natural for today's lab was covered in the lecture on natural selection. It might be helpful to review that material

Nuismer, Scott L.

44

The Nature of Naive Explanations of Natural Selection.  

ERIC Educational Resources Information Center

Suggests that misconceptions about natural selection arise from mistaken categorization. Proposes that students often fail to understand the ontological features of equilibrium processes. Contains 32 references. (DDR)

Ferrari, Michel; Chi, Michelene T. H.

1998-01-01

45

Natural Selection Because of Different Color: Camouflage  

NSDL National Science Digital Library

In this activity (p.5-6 of PDF), learners investigate natural selection. Learners discover that natural selection, which takes place over decades, can lead to altered populations within a species. Use this activity to explain the role of pollution and how humans can impact populations as well as compare natural selection to the development of antibiotic resistance in bacteria, which occurs much more quickly.

Dave Cavanagh

2012-11-14

46

Natural Selection in Relation to Complexity  

Microsoft Academic Search

Structural complexity characterizes our representations of dissipative structures. As a mechanistic concept, when referred to natural systems it generates perplexity in the face of logically sound models. Natural selection is a simple mechanistic concept, whose logic is well exemplified in genetic algorithms. While biological traits and functions do appear to have been subjected to selective culling, current neo-Darwinian theory is

2008-01-01

47

Natural Selection in a Petri Dish.  

ERIC Educational Resources Information Center

Presents an activity to teach natural selection that involves students in a microbiological investigation. Students discover that a change in environmental conditions tests a species' range of adaptations. (DDR)

McCarty, Robbie V.; Marek, Edmund A.

1997-01-01

48

Experiencing Natural Selection: Will You Survive?  

NSDL National Science Digital Library

This video from the Teaching Channel demonstrates the concept of natural selection. The engaging classroom activity, led by instructor Ceri Evans, addresses survival and natural selection and relates these ideas to the larger concept of evolution. The video may be shown to students to demonstrate these concepts, or may be used as the basis for a similar classroom activity. Running time for the video is 27:29.

2012-06-11

49

Natural Selection: Understanding Paley's Model  

NSDL National Science Digital Library

This information is intended to introduce students to the ideas proposed by William Paley in 1802 in the book Natural Theology. His model invokes the supernatural to explain adaptation and is a particularly clear example of the intelligent design ideas that were prevalent at that time. Students will have an opportunity to come to an understanding of the phenomena he was trying to explain, in part by reading an excerpt of his original writing. As an optional activity, students will have direct experience examining the structure of the mammalian eye that figured prominently in Paley's writing. Finally, they will work in groups to imagine some of the prior knowledge and beliefs that were central in Paley's thinking. This site includes detailed instructional notes for the teacher and all of the student handouts that are required.

50

Evoll - A Computer Based Natural Selection Game  

ERIC Educational Resources Information Center

Describes a computer-generated natural selection game which deals with various factors influencing survival and speciation processes. Variation of population size, growth rate, brood size, and selection pressure are permitted by the program, which is written in ASA Basic FORTRAN IV. (PR)

Wright, Ramil C.

1972-01-01

51

Natural and sexual selection against hybrid flycatchers  

PubMed Central

While sexual selection is generally assumed to quickly cause or strengthen prezygotic barriers between sister species, its role in causing postzygotic isolation, through the unattractiveness of intermediate hybrids, is less often examined. Combining 24 years of pedigree data and recently developed species-specific molecular markers from collared (Ficedula albicollis) and pied (Ficedula hypoleuca) flycatchers and their hybrids, we were able to quantify all key components of fitness. To disentangle the relative role of natural and sexual selection acting on F1 hybrid flycatchers, we estimated various fitness components, which when combined represent the total lifetime reproductive success of F1 hybrids, and then compared the different fitness components of F1 hybrids to that of collared flycatchers. Female hybrid flycatchers are sterile, with natural selection being the selective force involved, but male hybrids mainly experienced a reduction in fitness through sexual selection (decreased pairing success and increased rate of being cuckolded). To disentangle the role of sexual selection against male hybrids from a possible effect of genetic incompatibility (on the rate of being cuckolded), we compared male hybrids with pure-bred males expressing intermediate plumage characters. Given that sexual selection against male hybrids is a result of their intermediate plumage, we expect these two groups of males to have a similar fitness reduction. Alternatively, hybrids have reduced fitness owing to genetic incompatibility, in which case their fitness should be lower than that of the intermediate pure-bred males. We conclude that sexual selection against male hybrids accounts for approximately 75% of the reduction in their fitness. We discuss how natural and sexual selection against hybrids may have different implications for speciation and conclude that reinforcement of reproductive barriers may be more likely when there is sexual selection against hybrids. PMID:18211878

Svedin, Nina; Wiley, Chris; Veen, Thor; Gustafsson, Lars; Qvarnström, Anna

2008-01-01

52

Clippy Island: An Investigation into Natural Selection  

NSDL National Science Digital Library

In this activity, leaners will observe the process of natural selection on a population of birds called 'Springbeaks' over four seasons of breeding on an isolated environment called 'Clippy Island.' Learners will simulate feeding in a timed exercise to illustrate how a limited food supply and the introduction of genetic variants can lead to natural selection and adaptation. Learners will examine whether or not beak size affects the ability of a Springbeak to gather food and how this variation can affect successive generations in the population. This activity is designed for large groups of 30 learners but can work for smaller groups of at least 16 learners.

Furness, Lauren; Sutherland, Louise; Chalk, Hannah; Bulleid, Susan; Bamford, Amanda; Mcghie, Henry

2012-04-09

53

Natural selection. IV. The Price equation*  

PubMed Central

The Price equation partitions total evolutionary change into two components. The first component provides an abstract expression of natural selection. The second component subsumes all other evolutionary processes, including changes during transmission. The natural selection component is often used in applications. Those applications attract widespread interest for their simplicity of expression and ease of interpretation. Those same applications attract widespread criticism by dropping the second component of evolutionary change and by leaving unspecified the detailed assumptions needed for a complete study of dynamics. Controversies over approximation and dynamics have nothing to do with the Price equation itself, which is simply a mathematical equivalence relation for total evolutionary change expressed in an alternative form. Disagreements about approach have to do with the tension between the relative valuation of abstract versus concrete analyses. The Price equation’s greatest value has been on the abstract side, particularly the invariance relations that illuminate the understanding of natural selection. Those abstract insights lay the foundation for applications in terms of kin selection, information theory interpretations of natural selection, and partitions of causes by path analysis. I discuss recent critiques of the Price equation by Nowak and van Veelen. PMID:22487312

Frank, Steven A.

2012-01-01

54

Natural Selection 9-149 Chapter 9. NATURAL SELECTION AND BIOLOGICAL  

E-print Network

selection into the category of a discovery. Charles Darwin developed his basic theory of evolution Huxley (1825-1895), about Darwin's theory of Evolution by Nat- ural Selection. I. Introduction A created. B. Darwin's Contribution Natural selection is a model of how evolution works. Darwin is sometimes

Richerson, Peter J.

55

Sir Wyville Thomson and Natural Selection  

Microsoft Academic Search

I AM sorry to find that Sir Wyville Thomson does not under stand the principle of natural selection, as explained by Mr.Wallace and. myself. If he had done so, he could not have written the following sentence in the Introduction to the Voyage of the Challenger:-``The character of the abyssal fauna refuses to give the least support to the theory

Charles Darwin

1880-01-01

56

Fisher's Fundamental Theorem of Natural Selection Revisited  

Microsoft Academic Search

W. J. Ewens, following G. R. Price, has stressed that Fisher's fundamental theorem of natural selection about the increase in mean fitness is of general validity without any restrictive assumptions on the mating system, the fitness parameters, or the numbers of loci and alleles involved, but that it concerns only a partial change in mean fitness. This partial change is

Sabin Lessard

1997-01-01

57

A Lesson on Evolution & Natural Selection  

ERIC Educational Resources Information Center

I describe three activities that allow students to explore the ideas of evolution, natural selection, extinction, mass extinction, and rates of evolutionary change by engaging a simple model using paper, pens, chalk, and a chalkboard. As a culminating activity that supports expository writing in the sciences, the students write an essay on mass…

Curtis, Anthony D.

2010-01-01

58

Natural Selection and the Frequency Distributions of \\  

Microsoft Academic Search

In Escha'chia coli, Saccharomyces cereuisiae, and Drosophila melanogaster, codon bias may be maintained by a balance among mutation pressure, genetic drift, and natural selection favoring translationally superior codons. Under such an evolutionary model, silent mutations fall into two fitness categories: preferred mutations that increase codon bias and unpreferred changes in the opposite direction. This prediction can be tested by comparing

Hiroshi Akashi; Stephen W. Schaeffert

1997-01-01

59

Pervasive Natural Selection in the Drosophila Genome?  

Microsoft Academic Search

Over the past four decades, the predominant view of molecular evolution saw little connection between natural selection and genome evolution, assuming that the functionally constrained fraction of the genome is relatively small and that adaptation is sufficiently infrequent to play little role in shaping patterns of variation within and even between species. Recent evidence from Drosophila, reviewed here, suggests that

Guy Sella; Dmitri A. Petrov; Molly Przeworski; Peter Andolfatto

2009-01-01

60

Pervasive Natural Selection in the Drosophila Genome?  

Microsoft Academic Search

Over the past four decades, the predominant view of molecular evolution saw little connection between natural selection and genome evolution, assum- ing that the functionally constrained fraction of the genome is relatively small and that adaptation is sufficiently infrequent to play little role in shaping patterns of variation within and even between species. Recent evidence from Drosophila, reviewed here, suggests

Guy Sella; Dmitri A. Petrov; Molly Przeworski; Peter Andolfatto

2009-01-01

61

Redundant Gene Functions and Natural Selection  

Microsoft Academic Search

Redundant gene functions are ubiquitous, and they are a potentially important source of evolutionary innovations on the biochemical level. It is therefore highly desirable to understand the mechanisms governing their evolution. Gene duplication is clearly a prominent mechanism generating redundant genes. However, because redundancy provides a protective effect against deleterious mutations, natural selection might be involved in generating and maintaining

Andreas Wagner

1997-01-01

62

Darwin's explanation of design: from natural theology to natural selection.  

PubMed

Copernicus, Galileo, Newton and other physical scientists ushered in a conception of the universe as matter in motion governed by natural laws. Their discoveries brought about a fundamental revolution, namely a commitment to the postulate that the universe obeys immanent laws that can account for natural phenomena. The workings of the universe were brought into the realm of science: explanation through natural laws. Darwin completed the Copernican revolution by extending it to the living world. Darwin demonstrated the evolution of organisms. More important yet is that he discovered natural selection, the process that explains the "design" of organisms. The adaptations and diversity of organisms, the origin of novel and complex species, even the origin of mankind, could now be explained by an orderly process of change governed by natural laws. The origin of species and the exquisite features of organisms had previously been explained as special creations of an Omniscient God. Darwin brought them into the domain of science. Evolution is a creative process that produces genuine novelty. The creative power of evolution arises from a distinctive interaction between chance and necessity, between random mutation and natural selection. PMID:19800418

Ayala, Francisco J

2010-08-01

63

Natural selection in action during speciation  

PubMed Central

The role of natural selection in speciation, first described by Darwin, has finally been widely accepted. Yet, the nature and time course of the genetic changes that result in speciation remain mysterious. To date, genetic analyses of speciation have focused almost exclusively on retrospective analyses of reproductive isolation between species or subspecies and on hybrid sterility or inviability rather than on ecologically based barriers to gene flow. However, if we are to fully understand the origin of species, we must analyze the process from additional vantage points. By studying the genetic causes of partial reproductive isolation between specialized ecological races, early barriers to gene flow can be identified before they become confounded with other species differences. This population-level approach can reveal patterns that become invisible over time, such as the mosaic nature of the genome early in speciation. Under divergent selection in sympatry, the genomes of incipient species become temporary genetic mosaics in which ecologically important genomic regions resist gene exchange, even as gene flow continues over most of the genome. Analysis of such mosaic genomes suggests that surprisingly large genomic regions around divergently selected quantitative trait loci can be protected from interrace recombination by “divergence hitchhiking.” Here, I describe the formation of the genetic mosaic during early ecological speciation, consider the establishment, effects, and transitory nature of divergence hitchhiking around key ecologically important genes, and describe a 2-stage model for genetic divergence during ecological speciation with gene flow. PMID:19528641

Via, Sara

2009-01-01

64

Investigating Natural Selection: Middle and High School  

NSDL National Science Digital Library

This lesson plan is designed for middle or high school students learning about natural selection. Students will learn how predators select their prey, and how the survival of members of a species with certain qualities can affect subsequent populations of that species. Several discussion questions are included which can be used as a post-activity quiz or to support a larger classroom discussion. The activity may be changed to suit either middle or high school grade levels. The activity is intended to take about sixty minutes of class time.

2012-05-21

65

The Mechanisms of Evolution: Natural Selection and Natural Conventions  

Microsoft Academic Search

The mechanisms of evolution have been one of the most controversial issues in Biology and the great debate about them has\\u000a culminated, in the 1930s and 1940s, in the Modern Synthesis, the theoretical framework where natural selection is regarded\\u000a as the sole mechanism of evolutionary change. Here it is shown that a new approach to these great problems is provided

Marcello Barbieri

66

The status of cosmological natural selection  

E-print Network

The problem of making predictions from theories that have landscapes of possible low energy parameters is reviewed. Conditions for such a theory to yield falsifiable predictions for doable experiments are given. It is shown that the hypothesis of cosmological natural selection satisfies these conditions, thus showing that it is possible to continue to do physics on a landscape without invoking the anthropic principle. In particular, this is true whether or not the ensemble of universes generated by black holes bouncing is a sub-ensemble of a larger ensemble that might be generated by a random process such as eternal inflation. A recent criticism of cosmological natural selection made by Vilenkin in hep-th/0610051 is discussed. It is shown to rely on assumptions about both the infrared and ultraviolet behavior of quantum gravity that are very unlikely to be true.

Lee Smolin

2006-12-18

67

Measuring the Intensity of Natural Selection  

Microsoft Academic Search

HALDANE1 put forward a general measure of the intensity of natural selection. If W0 is the chance of survival of an individual with the optimum phenotype and Wmacr is the mean chance of survival in the population, then Haldane's measure is H = loge W0-loge Wmacr. Van Valen2 uses the measure I=(W0-Wmacr)\\/W0 which is simply the proportion of individuals that

P. O'Donald

1968-01-01

68

Symbiogenesis, natural selection, and the dynamic Earth.  

PubMed

One century ago, Constantin S. Mereschkowsky introduced the symbiogenesis theory for the origin of chloroplasts from ancient cyanobacteria which was later supplemented by Ivan E. Wallin's proposal that mitochondria evolved from once free-living bacteria. Today, this Mereschkowsky-Wallin principle of symbiogenesis, which is also known as the serial primary endosymbiosis theory, explains the evolutionary origin of eukaryotic cells and hence the emergence of all eukaryotes (protists, fungi, animals and plants). In 1858, the concept of natural selection was described independently by Charles Darwin and Alfred R. Wallace. In the same year, Antonio Snider-Pellegrini proposed the idea of shifting continents, which was later expanded by Alfred Wegener, who published his theory of continental drift eight decades ago. Today, directional selection is accepted as the major cause of adaptive evolution within natural populations of micro- and macro-organisms and the theory of the dynamic Earth (plate tectonics) is well supported. In this article, I combine the processes and principles of symbiogenesis, natural selection and the dynamic Earth and propose an integrative 'synade-model' of macroevolution which takes into account organisms from all five Kingdoms of life. PMID:19399544

Kutschera, U

2009-08-01

69

Natural selection, mental modules and intelligence.  

PubMed

The question of whether intelligence is one trait or many has exercised several generations of researchers, but no consensus is in sight. Evolutionary psychology, with its emphasis on domain-specific mental modules, seems to offer hope for advancing understanding of this question. We know that the mind has been shaped by natural selection to maximize reproductive success. This tells us what the mind must do--it must solve the adaptive problems that the organism confronts. However, whether this functional capacity is manifest in congruent anatomic, physiological, genetic, cognitive or psychometric structures is another matter. Examination of how natural selection shaped other mechanisms suggests that knowing functional demands provides only modest guidance as to the structure of mechanisms. None the less, it remains simultaneously clear that these mechanisms are not entirely general, but have been shaped to cope with specific challenges. Our metaphors for the mind, whether as a digital computer or a Swiss army knife, are misleading because computers and tools are products of intelligent design. In contrast, minds are products of natural selection whose intertwined components are products of incorporated genetic mutations whose effects are widespread and constrained by historical precedents. Our tendencies to describe the structure of the mind in terms of discrete components make it difficult for us to comprehend the mind as a mind. One antidote may be to minimize metaphorical descriptions of postulated structures of mind and focus instead on its function. PMID:11276912

Nesse, R M

2000-01-01

70

COMPUTATIONAL SCIENCE AT BROOKHAVEN NATIONAL LABORATORY: THREE SELECTED TOPICS.  

SciTech Connect

We present an overview of computational science at Brookhaven National Laboratory (BNL), with selections from three areas: fluids, nanoscience, and biology. The work at BNL in each of these areas is itself very broad, and we select a few topics for presentation within each of them.

DAVENPORT,J.W.DENG,Y.GLIMM,J.SAMULYAK,R.

2003-09-15

71

Natural and sexual selection in a monogamous historical human population  

E-print Network

Natural and sexual selection in a monogamous historical human population Alexandre Courtiola,b,c,1 selection in natural populations are well established, our understanding of selection in humans has been of natural and sexual selection in humans that includes the effects of sex and wealth on different episodes

Lummaa, Virpi

72

Laboratory Estimates of Heritabilities and Genetic Correlations in Nature  

PubMed Central

A lower bound on heritability in a natural environment can be determined from the regression of offspring raised in the laboratory on parents raised in nature. An estimate of additive genetic variance in the laboratory is also required. The estimated lower bounds on heritabilities can sometimes be used to demonstrate a significant genetic correlation between two traits in nature, if their genetic and phenotypic correlations in nature have the same sign, and if sample sizes are large, and heritabilities and phenotypic and genetic correlations are high. PMID:2515111

Riska, B.; Prout, T.; Turelli, M.

1989-01-01

73

Mate Choice in Soldier Beetles: Field & Laboratory Experiments that Demonstrate Sexual Selection in Action  

ERIC Educational Resources Information Center

Although the theory of evolution is the foundation of modern biology, students too rarely have an opportunity to watch selection operate in natural populations of animals. This lack may be partially responsible for the unfortunate ignorance of many people regarding the significance of evolution in biology. Laboratory exercises that directly study…

Eason, Perri K.; Sherman, Peter T.

2003-01-01

74

Darwin's finches: population variation and natural selection.  

PubMed Central

Van Valen's model, which relates morphological variation to ecological variation in an adaptive scheme, was investigated with individually marked and measured Darwin's finches on two adjacent Galápagos islands, Santa Cruz and Daphne Major. Results show that environmental heterogeneity is correlated with large continuous, morphological variation: variation in bill dimensions of Geospiza fortis is greater on Santa Cruz than on Daphne, as is environmental heterogeneity. Within populations of this species, different phenotypes distribute themselves in different habitat patches, select foods of different sizes and hardness, and exploit them with efficiencies that are phenotype- (bill size) dependent. These data constitute indirect evidence that natural selection has a controlling influence over the level of phenotypic variation exhibited by a population. Further evidence is that phenotypes did not survive equally well during the study period; on Daphne island G. fortis was apparently subjected to directional selection on bill tip length and G. scandens to normalizing selection on body weight and bill depth. Other factors which may have contributed to the establishment of a difference in variation between Santa Cruz and Daphne populations are the founder effect, genetic drift, and assortative mating. Annual climatic unpredictability is considered a source of environmental heterogeneity which, through its effect upon food supply, favors large morphological variation. It is predicted that species of large individual size are more influenced by this than are small species, and consequently exhibit greater size-corrected variation. The prediction is tested with data from six Geospiza species, and found to be correct. PMID:1061123

Grant, P R; Grant, B R; Smith, J N; Abbott, I J; Abbott, L K

1976-01-01

75

The inductive theory of natural selection  

E-print Network

The theory of natural selection has two forms. Deductive theory describes how populations change over time. One starts with an initial population and some rules for change. From those assumptions, one calculates the future state of the population. Deductive theory predicts how populations adapt to environmental challenge. Inductive theory describes the causes of change in populations. One starts with a given amount of change. One then assigns different parts of the total change to particular causes. Inductive theory analyzes alternative causal models for how populations have adapted to environmental challenge. This chapter emphasizes the inductive analysis of cause.

Frank, Steven A

2014-01-01

76

Natural Image Statistics and Low-Complexity Feature Selection  

E-print Network

Natural Image Statistics and Low-Complexity Feature Selection Manuela Vasconcelos and Nuno Vasconcelos, Senior Member, IEEE Abstract--Low-complexity feature selection is analyzed in the context information for discrimination of natural images. This hypothesis is characterized formally

Vasconcelos, Nuno M.

77

Using Card Games to Simulate the Process of Natural Selection  

ERIC Educational Resources Information Center

In 1858, Darwin published "On the Origin of Species by Means of Natural Selection." His explanation of evolution by natural selection has become the unifying theme of biology. We have found that many students do not fully comprehend the process of evolution by natural selection. We discuss a few simple games that incorporate hands-on…

Grilliot, Matthew E.; Harden, Siegfried

2014-01-01

78

Implications of the Reduction Principle for Cosmological Natural Selection  

E-print Network

Implications of the Reduction Principle for Cosmological Natural Selection Lee Altenberg Associate reproduction -- Cosmological Natural Selection (CNS) -- in which black hole collapses give rise to offspring to account for high fidelity of inheritance between universes. Moreover, it reveals that natural selection

Altenberg, Lee

79

NATURAL SELECTION AND MATING CONSTRAINTS WITH GENETIC Dana Vrajitoru  

E-print Network

NATURAL SELECTION AND MATING CONSTRAINTS WITH GENETIC ALGORITHMS Dana Vrajitoru Intelligent Systems generations under the influence of natural selection. The study of the sexual reproduction and of the mat- ing. The phenomenon of natural selection of the living be- ings combined with the preservation of the genetic diver

Vrajitoru, Dana

80

Research article Measuring natural selection on proportional traits  

E-print Network

Research article Measuring natural selection on proportional traits: comparisons of three types: I. Olivieri Abstract. To compare the strength of natural selection on different traits a useful tool for studying natural selection on proportional traits, because by definition they measure how

Stinchcombe, John

81

Recoding of the stop codon UGA to glycine by a BD1-5/SN-2 bacterium and niche partitioning between Alpha- and Gammaproteobacteria in a tidal sediment microbial community naturally selected in a laboratory chemostat  

PubMed Central

Sandy coastal sediments are global hotspots for microbial mineralization of organic matter and denitrification. These sediments are characterized by advective porewater flow, tidal cycling and an active and complex microbial community. Metagenomic sequencing of microbial communities sampled from such sediments showed that potential sulfur oxidizing Gammaproteobacteria and members of the enigmatic BD1-5/SN-2 candidate phylum were abundant in situ (>10% and ~2% respectively). By mimicking the dynamic oxic/anoxic environmental conditions of the sediment in a laboratory chemostat, a simplified microbial community was selected from the more complex inoculum. Metagenomics, proteomics and fluorescence in situ hybridization showed that this simplified community contained both a potential sulfur oxidizing Gammaproteobacteria (at 24 ± 2% abundance) and a member of the BD1-5/SN-2 candidate phylum (at 7 ± 6% abundance). Despite the abundant supply of organic substrates to the chemostat, proteomic analysis suggested that the selected gammaproteobacterium grew partially autotrophically and performed hydrogen/formate oxidation. The enrichment of a member of the BD1-5/SN-2 candidate phylum enabled, for the first time, direct microscopic observation by fluorescent in situ hybridization and the experimental validation of the previously predicted translation of the stop codon UGA into glycine. PMID:24904545

Hanke, Anna; Hamann, Emmo; Sharma, Ritin; Geelhoed, Jeanine S.; Hargesheimer, Theresa; Kraft, Beate; Meyer, Volker; Lenk, Sabine; Osmers, Harald; Wu, Rong; Makinwa, Kofi; Hettich, Robert L.; Banfield, Jillian F.; Tegetmeyer, Halina E.; Strous, Marc

2014-01-01

82

Recoding of the stop codon UGA to glycine by a BD1-5/SN-2 bacterium and niche partitioning between Alpha- and Gammaproteobacteria in a tidal sediment microbial community naturally selected in a laboratory chemostat  

SciTech Connect

Sandy coastal sediments are global hot spots for microbial mineralization of organic matter and denitrification. These sediments are characterized by advective pore water flow, tidal cycling and an active and complex microbial community. Metagenomic sequencing of microbial communities sampled from such sediments showed that potential sulfuroxidizing Gammaproteobacteria and members of the enigmaticBD1-5/ SN-2 candidatephylumwereabundantinsitu (>10% and 2% respectively). By mimicking the dynamic oxic/anoxic environmental conditions of the sedimentin a laboratory chemostat, a simplified microbial community was selected from the more complex inoculum. Metagenomics, proteomics and fluorescenceinsituhybridization showed that this simplified community contained both a potential sulfuroxidizing Gamma proteobacteria (at 24 2% abundance) and a member of the BD1-5 / SN-2candidatephylum (at 7 6%abundance). Despite the abundant supply of organic substrates to the chemostat, proteomic analysis suggested that the selected gamma proteobacterium grew partially auto trophically and performed hydrogen/formate oxidation. The enrichment of a member of the BD1-5/SN-2candidatephylum enabled, for the first time, direct microscopic observation by fluorescent insitu hybridization and the experimental validation of the previously predicted translation of the stop codon UGA into glycine.

Hanke, Anna [Max Planck Institute for Marine Microbiology; Hamann, Emmo [Max Planck Institute for Marine Microbiology; Sharma, Ritin [ORNL; Geelhoed, Jeanine [Max Planck Institute for Marine Microbiology; Hargesheimer, Theresa [Max Planck Institute for Marine Microbiology; Kraft, Beate [Max Planck Institute for Marine Microbiology; Meyer, Volker [Max Planck Institute for Marine Microbiology; Lenk, Sabine [Max Planck Institute for Marine Microbiology; Osmers, Harald [Max Planck Institute for Marine Microbiology; Wu, Rong [Delft University of Technology, Delft, Netherlands; Makinwa, Kofi [Delft University of Technology, Delft, Netherlands; Hettich, Robert {Bob} L [ORNL; Banfield, Jillian F. [University of California, Berkeley; Tegetmeyer, Halina [Max Planck Institute for Marine Microbiology; Strouss, Marc [University of Calgary, ALberta, Canada

2014-01-01

83

Recoding of the stop codon UGA to glycine by a BD1-5/SN-2 bacterium and niche partitioning between Alpha- and Gammaproteobacteria in a tidal sediment microbial community naturally selected in a laboratory chemostat.  

PubMed

Sandy coastal sediments are global hotspots for microbial mineralization of organic matter and denitrification. These sediments are characterized by advective porewater flow, tidal cycling and an active and complex microbial community. Metagenomic sequencing of microbial communities sampled from such sediments showed that potential sulfur oxidizing Gammaproteobacteria and members of the enigmatic BD1-5/SN-2 candidate phylum were abundant in situ (>10% and ~2% respectively). By mimicking the dynamic oxic/anoxic environmental conditions of the sediment in a laboratory chemostat, a simplified microbial community was selected from the more complex inoculum. Metagenomics, proteomics and fluorescence in situ hybridization showed that this simplified community contained both a potential sulfur oxidizing Gammaproteobacteria (at 24 ± 2% abundance) and a member of the BD1-5/SN-2 candidate phylum (at 7 ± 6% abundance). Despite the abundant supply of organic substrates to the chemostat, proteomic analysis suggested that the selected gammaproteobacterium grew partially autotrophically and performed hydrogen/formate oxidation. The enrichment of a member of the BD1-5/SN-2 candidate phylum enabled, for the first time, direct microscopic observation by fluorescent in situ hybridization and the experimental validation of the previously predicted translation of the stop codon UGA into glycine. PMID:24904545

Hanke, Anna; Hamann, Emmo; Sharma, Ritin; Geelhoed, Jeanine S; Hargesheimer, Theresa; Kraft, Beate; Meyer, Volker; Lenk, Sabine; Osmers, Harald; Wu, Rong; Makinwa, Kofi; Hettich, Robert L; Banfield, Jillian F; Tegetmeyer, Halina E; Strous, Marc

2014-01-01

84

Department of Biological Sciences Detecting Natural Selection in Real Time:Detecting Natural Selection in Real Time  

E-print Network

Rich King Department of Biological Sciences Detecting Natural Selection in Real Time:Detecting Natural Selection in Real Time: Examples from Lake Erie Snake PopulationsExamples from Lake Erie Snake Populations #12;What is Natural Selection? As many more individuals of each species are born than can possibly

King, Richard B.

85

Reproduction of natural corrosion by accelerated laboratory testing methods  

SciTech Connect

Various laboratory corrosion tests have been developed to study the behavior of glass waste forms under conditions similar to those expected in an engineered repository. The data generated by laboratory experiments are useful for understanding corrosion mechanisms and for developing chemical models to predict the long-term behavior of glass. However, it is challenging to demonstrate that these test methods produce results that can be directly related to projecting the behavior of glass waste forms over time periods of thousands of years. One method to build confidence in the applicability of the test methods is to study the natural processes that have been taking place over very long periods in environments similar to those of the repository. In this paper, we discuss whether accelerated testing methods alter the fundamental mechanisms of glass corrosion by comparing the alteration patterns that occur in naturally altered glasses with those that occur in accelerated laboratory environments. This comparison is done by (1) describing the alteration of glasses reacted in nature over long periods of time and in accelerated laboratory environments and (2) establishing the reaction kinetics of naturally altered glass and laboratory reacted glass waste forms.

Luo, J.S.; Wronkiewicz, D.J.; Mazer, J.J.; Bates, J.K.

1996-05-01

86

2006 Nature Publishing Group Intensity of sexual selection along the  

E-print Network

© 2006 Nature Publishing Group Intensity of sexual selection along the anisogamy­isogamy continuum the foundations of sexual selection theory. Post- copulatory sexual selection on males (that is, sperm competition . However, a decline in sperm numbers is predicted to weaken selection on males and increase selection

Pitnick, Scott

87

Selective particle ingestion by oyster larvae ( Crassostrea virginica ) feeding on natural seston and cultured algae  

Microsoft Academic Search

I investigated selective particle ingestion by oyster larvae (Crassostrea virginica) feeding on natural seston from Chesapeake Bay and laboratory-cultured algae of different sizes or chemical content. In 15 of 16 experiments with complex natural suspensions as food, small(150 µm) larvae selected most strongly for small (2 to 4 µm) food particles, but in the presence of a large (>10 µm)-cell

B. S. Baldwin

1995-01-01

88

The snowmaker: nature identical snow production in the laboratory  

NASA Astrophysics Data System (ADS)

Using natural snow for laboratory experiments can be tricky due to shortage of winter periods and snowfall, difficulties of sample casting and transport, and the great variability of natural snow due to the varying conditions of crystal growth in the clouds. This hinders repeatable laboratory experiments with reproducible specimen and microstructural characteristics. To minimize experimental uncertainties we designed an improved machine called snowmaker, which enables us to produce nature-identical snow in a cold laboratory under well defined conditions. The snowmaker is based on well-known principles: warm humid air from a heated water basin is advected into a cold nucleation chamber where the vapor resublimates on stretched Nylon wires. Crystals are automatically harvested by a motor driven brush rack and collected in a box, thereby several kilograms of snow can be produced per day with minimum maintenance. The excess vapor is collected in a moisture trap to avoid frost in the laboratory. The entire construction is designed as a rolling, modular assembly system which can easily carried out of the laboratory for defrosting. In addition to previous attempts we focus on the reproducibility of the samples and the comparison to natural snow down to the microscale. We show that the settings of water temperature and cold laboratory temperature facilitates the production of different crystal shapes like dendrites and needles in a reproducible way. Besides photography, we analyzed the microstructure of snowmaker crystals in aggregated specimen by X-ray microtomography. Depending on the settings we can create reproducible samples with density of 50-170 kg/m3 and specific surface areas of 50-80 mm-1. We briefly touch similarities between artificial and natural snow samples with respect to crystal habit, microstructural parameters and short-time metamorphism.

Schleef, S.; Jaggi, M.; Loewe, H.; Schneebeli, M.

2013-12-01

89

164 nature physics | VOL 5 | MARCH 2009 | www.nature.com/naturephysics A quantum of natural selection  

E-print Network

of natural selection Seth Lloyd The modern evolutionary synthesis, which marries Darwin's theory of natural of natural selection. Perhaps the most surprising aspect of the book is that Darwin was able to construct his theory of how physical traits were handed down and naturally selected, despite operating

Loss, Daniel

90

The Nature of Laboratory Learning Experiences in Secondary Science Online  

ERIC Educational Resources Information Center

Teaching science to secondary students in an online environment is a growing international trend. Despite this trend, reports of empirical studies of this phenomenon are noticeably missing. With a survey concerning the nature of laboratory activities, this study describes the perspective of 35-secondary teachers from 15-different U.S. states who…

Crippen, Kent J.; Archambault, Leanna M.; Kern, Cindy L.

2013-01-01

91

SERUM ALBUMIN POLYMORPHISMS IN NATURAL AND LABORATORY POPULATIONS OF PEROMYSCUS  

E-print Network

SERUM ALBUMIN POLYMORPHISMS IN NATURAL AND LABORATORY POPULATIONS OF PEROMYSCUS JAMES H. BROWN AND CARL F. WELSER ABSTRACT.-Electrophoresisof serum from 14 species of Peromyscus revealed albumin populations of small mammals in general, and of Peromyscus in particular, has largely been ne- glected

Brown, James H.

92

Microbial Resistance to Triclosan: A Case Study in Natural Selection  

ERIC Educational Resources Information Center

Natural selection is the mechanism of evolution caused by the environmental selection of organisms most fit to reproduce, sometimes explained as "survival of the fittest." An example of evolution by natural selection is the development of bacteria that are resistant to antimicrobial agents as a result of exposure to these agents. Triclosan, which…

Serafini, Amanda; Matthews, Dorothy M.

2009-01-01

93

NATURAL SELECTION ON COLOR PATTERNS IN POECILIA RETICULATA  

Microsoft Academic Search

All too often in evolutionary biology we are led to speculate or infer the mode of action of natural selection; we usually do not know why some individuals are more adaptive than others. Very often attempts to measure natural selection are unsuc- cessful, leading to heated arguments about the relative importance of selection, ge- netic drift, and epistasis in evolution

JOHN A. ENDLER

1980-01-01

94

A Working Model of Natural Selection Illustrated by Table Tennis  

ERIC Educational Resources Information Center

Natural selection is one of the most important topics in biology and it helps to clarify the variety and complexity of organisms. However, students in almost every stage of education find it difficult to understand the mechanism of natural selection and they can develop misconceptions about it. This article provides an active model of natural

Dinc, Muhittin; Kilic, Selda; Aladag, Caner

2013-01-01

95

Using path analysis to measure natural selection  

Microsoft Academic Search

We expand current methods for calculating selection coefficients using path analysis and demonstrate how to analyse nonlinear selection. While this incorporation is a straightforward extension of current procedures, the rules for combining these traits to calculate selection coefficients can be complex. We demonstrate our method with an analysis of selection in an experimental population of Arabidopsis thaliana consisting of 289

Scheiner; H. S. CALLAHAN

2000-01-01

96

Good genes sexual selection in nature.  

PubMed

Whether the mate sampling and choice performed by females in nature influences offspring performance is a controversial issue in theory and an open empirical question. Pronghorn (Antilocapra americana) females engage in an obvious and energetically expensive mate sampling process to identify vigorous males. Although individual females sample independently, their choices converge on a small proportion of males that sire most young. Offspring of attractive males were more likely to survive to weaning and to age classes as late as 5 years, resulting in a selection differential, calculated by expected differences in lifetime number of offspring weaned, of 0.32 against random mating. Enhanced survival to weaning appeared to be accomplished by faster growth rates. Females compensated for matings with a less attractive mate by elevating rates of milk delivery to their young. Because pronghorn males do not have costly ornaments, we conclude that female choice for good genes can exist in the absence of ornaments. Furthermore, female choice may be important and unrecognized as a force that can lower population genetic load. PMID:17060640

Byers, John A; Waits, Lisette

2006-10-31

97

Good genes sexual selection in nature  

PubMed Central

Whether the mate sampling and choice performed by females in nature influences offspring performance is a controversial issue in theory and an open empirical question. Pronghorn (Antilocapra americana) females engage in an obvious and energetically expensive mate sampling process to identify vigorous males. Although individual females sample independently, their choices converge on a small proportion of males that sire most young. Offspring of attractive males were more likely to survive to weaning and to age classes as late as 5 years, resulting in a selection differential, calculated by expected differences in lifetime number of offspring weaned, of 0.32 against random mating. Enhanced survival to weaning appeared to be accomplished by faster growth rates. Females compensated for matings with a less attractive mate by elevating rates of milk delivery to their young. Because pronghorn males do not have costly ornaments, we conclude that female choice for good genes can exist in the absence of ornaments. Furthermore, female choice may be important and unrecognized as a force that can lower population genetic load. PMID:17060640

Byers, John A.; Waits, Lisette

2006-01-01

98

Natural selection and the elusiveness of happiness.  

PubMed Central

The quest for happiness has expanded from a focus on relieving suffering to also considering how to promote happiness. However, both approaches have yet to be conducted in an evolutionary framework based on the situations that shaped the capacities for happiness and sadness. Because of this, the emphasis has almost all been on the disadvantages of negative states and the benefits of positive states, to the nearly total neglect of 'diagonal psychology', which also considers the dangers of unwarranted positive states and the benefits of negative emotions in certain situations. The situations that arise in goal pursuit contain adaptive challenges that have shaped domain-general positive and negative emotions that were partially differentiated by natural selection to cope with the more specific situations that arise in the pursuit of different kinds of goals. In cultures where large social groups give rise to specialized and competitive social roles, depression may be common because regulation systems are pushed far beyond the bounds for which they were designed. Research on the evolutionary origins of the capacities for positive and negative emotions is urgently needed to provide a foundation for sensible decisions about the use of new mood-manipulating technologies. PMID:15347525

Nesse, Randolph M

2004-01-01

99

NATURAL RESOURCE MANAGEMENT PLAN FOR BROOKHAVEN NATIONAL LABORATORY.  

SciTech Connect

Brookhaven National Laboratory (BNL) is located near the geographic center of Long Island, New York. The Laboratory is situated on 5,265 acres of land composed of Pine Barrens habitat with a central area developed for Laboratory work. In the mid-1990s BNL began developing a wildlife management program. This program was guided by the Wildlife Management Plan (WMP), which was reviewed and approved by various state and federal agencies in September 1999. The WMP primarily addressed concerns with the protection of New York State threatened, endangered, or species of concern, as well as deer populations, invasive species management, and the revegetation of the area surrounding the Relativistic Heavy Ion Collider (RHIC). The WMP provided a strong and sound basis for wildlife management and established a basis for forward motion and the development of this document, the Natural Resource Management Plan (NRMP), which will guide the natural resource management program for BNL. The body of this plan establishes the management goals and actions necessary for managing the natural resources at BNL. The appendices provide specific management requirements for threatened and endangered amphibians and fish (Appendices A and B respectively), lists of actions in tabular format (Appendix C), and regulatory drivers for the Natural Resource Program (Appendix D). The purpose of the Natural Resource Management Plan is to provide management guidance, promote stewardship of the natural resources found at BNL, and to integrate their protection with pursuit of the Laboratory's mission. The philosophy or guiding principles of the NRMP are stewardship, adaptive ecosystem management, compliance, integration with other plans and requirements, and incorporation of community involvement, where applicable.

GREEN,T.ET AL.

2003-12-31

100

Laboratory selection for increased longevity in Drosophila melanogaster reduces field performance.  

PubMed

Drosophila melanogaster is frequently used in ageing studies to elucidate which mechanisms determine the onset and progress of senescence. Lines selected for increased longevity have often been shown to perform as well as or superior to control lines in life history, stress resistance and behavioural traits when tested in the laboratory. Functional senescence in longevity selected lines has also been shown to occur at a slower rate. However, it is known that performance in a controlled laboratory setting is not necessarily representative of performance in nature. In this study the effect of ageing, environmental temperature and longevity selection on performance in the field was tested. Flies from longevity selected and control lines of different ages (2, 5, 10 and 15 days) were released in an environment free of natural food sources. Control flies were tested at low, intermediate and high temperatures, while longevity selected flies were tested at the intermediate temperature only. The ability of flies to locate and reach a food source was tested. Flies of intermediate age were generally better at locating resources than both younger and older flies, where hot and cold environments accelerate the senescent decline in performance. Control lines were better able to locate a resource compared to longevity selected lines of the same age, suggesting that longevity comes at a cost in early life field fitness, supporting the antagonistic pleiotropy theory of ageing. PMID:23916841

Wit, Janneke; Kristensen, Torsten Nygaard; Sarup, Pernille; Frydenberg, Jane; Loeschcke, Volker

2013-11-01

101

Compressed natural gas and liquefied petroleum gas conversions: The National Renewable Energy Laboratory`s experience  

Microsoft Academic Search

The National Renewable Energy Laboratory (NREL) contracted with conversion companies in six states to convert approximately 900 light-duty Federal fleet vehicles to operate on compressed natural gas (CNG) or liquefied petroleum gas (LPG). The contracts were initiated in order to help the Federal government meet the vehicle acquisition requirements of the Energy Policy Act of 1992 (EPACT) during a period

R. C. Motta; K. J. Kelly; W. W. Warnock

1996-01-01

102

Sexual selection and natural selection in bird speciation  

PubMed Central

The role of sexual selection in speciation is investigated, addressing two main issues. First, how do sexually selected traits become species recognition traits? Theory and empirical evidence suggest that female preferences often do not evolve as a correlated response to evolution of male traits. This implies that, contrary to runaway (Fisherian) models of sexual selection, premating isolation will not arise as an automatic side effect of divergence between populations in sexually selected traits. I evaluate premating isolating mechanisms in one group, the birds. In this group premating isolation is often a consequence of sexual imprinting, whereby young birds learn features of their parents and use these features in mate choice. Song, morphology and plumage are known recognition cues. I conclude that perhaps the main role for sexual selection in speciation is in generating differences between populations in traits. Sexual imprinting then leads to these traits being used as species recognition mechanisms. The second issue addressed in this paper is the role of sexual selection in adaptive radiation, again concentrating on birds. Ecological differences between species include large differences in size, which may in themselves be sufficient for species recognition, and differences in habitat, which seem to evolve frequently and at all stages of an adaptive radiation. Differences in habitat often cause song and plumage patterns to evolve as a result of sexual selection for efficient communication. Therefore sexual selection is likely to have an important role in generating premating isolating mechanisms throughout an adaptive radiation. It is also possible that sexual selection, by creating more allopatric species, creates more opportunity for ecological divergence to occur. The limited available evidence does not support this idea. A role for sexual selection in accelerating ecological diversification has yet to be demonstrated.

Price, T.

1998-01-01

103

Seal formation in arid soil under natural and laboratory conditions  

NASA Astrophysics Data System (ADS)

Runoff is of considerable importance in the functioning of a desert ecosystem. The hydrological characteristics of runoff developing on arid soil under natural field conditions and those of runoff occurring in laboratory-controlled rain simulation experiments using the same type of soil were investigated. Runoff and erosion measurements were carried out in small plots (0.2-0.8 m2) on a south-facing hillslope in the northern Negev, Israel (90 mm ave. annual rainfall). Soil from the area near to the runoff plots was collected for the rain simulation experiments conducted in the laboratory. The soil was collected from 0-1 cm and 1-5 cm depths, and then placed within boxes (1.16 m long and 0.55 m wide) in the laboratory in the same order as they had been in the field. Representative surface stones were collected in the field and scattered randomly on the soil surface in the laboratory boxes. In some of the laboratory experiments soil, 5 cm in depth, was placed on a geotechnical sheet on a metal screen, while in other experiments, soil of 5 cm depth was placed on a Terzaghi filter. Rain simulator used had a rotating disk with a tilted nozzle to simulate raindrop size dispersion and kinetic energy of natural rain. The sprinkling intensity was set at a rate of 18 mm/hour. Soil crusts in the field were more stable than those created in the lab for two standard tests: Emerson - immersion test, and the 'single water drop' test. Whereas weak activity of microphytes was found in the field there was no such activity in the lab. The rain depth until runoff in the field was less than under laboratory conditions, while the sediment yield was greater in the field than in the laboratory (8.64 g/m2 versus 0.58 g/m2). The rain simulator experiments that had included a Terzaghi filter showed significantly higher final infiltration rate (7.5 mm/h versus 4.2 mm/h), shorter accumulated watering depth until stabilization of soil seal formation (100-200 mm versus 50 mm), and smaller fraction of clay in the crust (4.2% versus 6.8%), than the experiments that done without this filter. Therefore, it is conceivable that there is a suction of thin material from the surface while capillary pressures are activated, result in sub-surface seal formation (washed-in layer). This can lead to differences between runoff-forming processes existing in the laboratory set-up and processes that occur under natural field conditions.

Sarah, Pariente; Sachs, Eyal

2013-04-01

104

Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection  

ERIC Educational Resources Information Center

Darwin's theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin's theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that…

Thagard, Paul; Findlay, Scott

2010-01-01

105

Development and evaluation of the conceptual inventory of natural selection  

Microsoft Academic Search

Natural selection as a mechanism of evolution is a central concept in biology; yet, most nonbiology-majors do not thoroughly understand the theory even after instruction. Many alternative conceptions on this topic have been identified, indicating that the job of the instructor is a difficult one. This article presents a new diagnostic test to assess students' understanding of natural selection. The

Dianne L. Anderson; Kathleen M. Fisher; Gregory J. Norman

2002-01-01

106

Historical Intensity of Natural Selection for Resistance to Tuberculosis  

Microsoft Academic Search

Infections have long been thought to exert natural selection on humans. Infectious disease resistance is frequently invoked as a mechanism shaping human genetic diversity, but such hypotheses have rarely been quantitatively evaluated with direct measures of disease-related mortality. Enhancement of genetically deter- mined resistance to tuberculosis by natural selection has been proposed as a factor explaining the decline of tuberculosis

Marc Lipsitch; Alexandra O. Sousa

2002-01-01

107

The Nature of Selection on Anhydrobiotic Capacityin Tardigrades  

Microsoft Academic Search

Tardigrades are well known for their capacity to enter an anhydrobiotic state, and remain ametabolic for several years. Yet the evolutionary background, and the forces of natural selection that act on anhydrobiotic capacity have remained unexplored. In this paper, I review the basic problem of anhydrobiosis and the phenotypic traits that may be the main targets of natural selection for

K. Ingemar Jönsson

2001-01-01

108

Inferring natural selection in a fossil threespine stickleback  

Microsoft Academic Search

Inferring the causes for change in the fossil record has been a persistent problem in evo- lutionary biology. Three independent lines of evidence indicate that a lineage of the fossil stick- leback fish Gasterosteus doryssus experienced directional natural selection for reduction of armor. Nonetheless, application to this lineage of three methods to infer natural selection in the fossil record could

Michael A. Bell; Matthew P. Travis; D. Max Blouw

2006-01-01

109

Adding Dynamical Sufficiency to Fisher's Fundamental Theorem of Natural Selection  

Microsoft Academic Search

Fisher's ``fundamental theorem of natural selection'' is famously robust and versatile but, frustratingly, it is dynamically insufficient: it can only predict how fitness will evolve over the course of a single generation. Consequently, his theorem has not been used for predicting the course of evolution but instead for detecting natural selection. His theorem employs only one facet of the fitness

Philip J. Gerrish; Paul D. Sniegowski

2011-01-01

110

ENHANCEMENTS TO NATURAL ATTENUATION: SELECTED CASE STUDIES  

SciTech Connect

In 2003 the US Department of Energy (DOE) embarked on a project to explore an innovative approach to remediation of subsurface contaminant plumes that focused on introducing mechanisms for augmenting natural attenuation to achieve site closure. Termed enhanced attenuation (EA), this approach has drawn its inspiration from the concept of monitored natural attenuation (MNA).

Vangelas, K; W. H. Albright, W; E. S. Becvar, E; C. H. Benson, C; T. O. Early, T; E. Hood, E; P. M. Jardine, P; M. Lorah, M; E. Majche, E; D. Major, D; W. J. Waugh, W; G. Wein, G; O. R. West, O

2007-05-15

111

Selection Is Entailed by Self-Organization and Natural Selection Is a Special Case  

Microsoft Academic Search

In their book, Darwinism Evolving: Systems Dynamics and the Genealogy of Natural Selection, Depew and Weber (1995) argued for the need to address the relationship between self-organization and natural selection in evolutionary theory, and focused on seven visions for doing so. Recently, Batten et al. (2008) in a paper in this journal, entitled Visions of evolution: self-organization proposes what natural

Rod Swenson

2010-01-01

112

Seasonal and Diel Habitat Selection by Bluegills in a Shallow Natural Lake  

Microsoft Academic Search

Habitat use by bluegill Lepomis macrochirus may be dictated by the avoidance of predators and the availability of prey. Previous work suggests that bluegills large enough to avoid predators will select habitats based on foraging profitability. However, these studies focused on smaller fish (<150 mm standard length) in laboratory experiments or in natural systems with distinct vegetated and open-water habitats.

Craig P. Paukert; David W. Willis

2002-01-01

113

Evolution of Competitive Ability in Drosophila by Density-Dependent Natural Selection  

Microsoft Academic Search

The theory of density-dependent natural selection predicts that populations kept at extreme densities should evolve different competitive abilities for limited resources. These predictions have been tested with laboratory populations of Drosophila melanogaster. Six independent populations were maintained in two environments, called r and K, for 128 generations. In the r environment, population sizes were small and resources for larvae and

Laurence D. Mueller

1988-01-01

114

On the natural selection rule in general linear models  

Microsoft Academic Search

We consider a problem of selecting the best treatment in a general linear model. We look at the properties of the natural\\u000a selection rule. It is shown that the natural selection rule is minimax under to “0–1” loss function and it is a Bayes rule\\u000a under a monotone permutation invariant loss function with respect to a permutation invariant prior for

Naveen K. Bansal; Sudhir Gupta

1997-01-01

115

Administration of Substances to Laboratory Animals: Equipment Considerations, Vehicle Selection, and Solute Preparation  

PubMed Central

Administration of substances to laboratory animals requires careful consideration and planning to optimize delivery of the agent to the animal while minimizing potential adverse experiences from the procedure. The equipment selected to deliver substances to animals depends on the length of the study and the nature of the material being administered. This selection provides a significant opportunity for refining animal treatment. Similarly, when substances are administered as solutions or suspensions, attention should be given to selection of vehicles and methods used for preparing the solutions and suspensions. The research team, veterinarian, technical personnel, and IACUC members should be aware of reasons underlying selection of equipment for substance delivery and should consider carefully how substances will be prepared and stored prior to administration to animals. Failure to consider these factors during experimental planning may result in unintentional adverse effects on experimental animals and confounded results. PMID:22330706

Turner, Patricia V; Pekow, Cynthia; Vasbinder, Mary Ann; Brabb, Thea

2011-01-01

116

Speciation by Natural and Sexual Selection: Models and Experiments  

Microsoft Academic Search

A large number of mathematical models have been de- veloped that show how natural and sexual selection can cause pre- zygotic isolation to evolve. This article attempts to unify this literature by identifying five major elements that determine the outcome of speciation caused by selection: a form of disruptive selection, a form of isolating mechanism (assortment or a mating preference),

Mark Kirkpatrick; Virginie Ravigné

2002-01-01

117

Pollinator-mediated natural selection in Penstemon digitalis  

PubMed Central

Measuring the agents of natural selection is important because it allows us to understand not only which traits are expected to evolve but also why they will evolve. Natural selection by pollinators on floral traits is often assumed because in outcrossing animal-pollinated plants flowers are generally thought to function as advertisements of rewards directed at pollinators. We tested the role of bee pollinators in selection on Penstemon digitalis and found that pollinators were driving selection for larger and more flowers. However, what makes our publication unique is the additional information we gained from reviewing the few other studies that also directly tested whether pollinators were agents of selection on floral traits. As we would expect if pollinators are important agents of selection, selection on floral traits was significantly stronger when pollinators were present than when their choices were experimentally removed. Taken together, these results suggest that pollinators can be important drivers of selection in contemporary populations. PMID:21150291

Kessler, André

2010-01-01

118

The College Language Laboratory: Selected Work Papers Presented at the Conference on the College Language Laboratory, November 1960.  

ERIC Educational Resources Information Center

Selected papers of a conference dealing with development and use of language laboratories in the early 1960's are presented in this publication. Selections include: (1) F. R. Morton's "Recent Developments in Language Laboratory Equipment for Teaching and Research", (2) Pierre Delattre's "Testing the Oral Production of Language Students", (3)…

Morton, F. Rand, Ed.

119

Balancing natural and sexual selection in sockeye salmon: interactions between body size, reproductive  

E-print Network

Balancing natural and sexual selection in sockeye salmon: interactions between body size differ in phenotypic traits associated with natural and sexual selection. We used two proximate, predation, reproductive success. INTRODUCTION Natural and sexual selection often oppose each other in nature

Hendry, Andrew

120

Adaptation of Drosophila to a novel laboratory environment reveals temporally heterogeneous trajectories of selected alleles  

PubMed Central

The genomic basis of adaptation to novel environments is a fundamental problem in evolutionary biology that has gained additional importance in the light of the recent global change discussion. Here, we combined laboratory natural selection (experimental evolution) in Drosophila melanogaster with genome-wide next generation sequencing of DNA pools (Pool-Seq) to identify alleles that are favourable in a novel laboratory environment and traced their trajectories during the adaptive process. Already after 15 generations, we identified a pronounced genomic response to selection, with almost 5000 single nucleotide polymorphisms (SNP; genome-wide false discovery rates < 0.005%) deviating from neutral expectation. Importantly, the evolutionary trajectories of the selected alleles were heterogeneous, with the alleles falling into two distinct classes: (i) alleles that continuously rise in frequency; and (ii) alleles that at first increase rapidly but whose frequencies then reach a plateau. Our data thus suggest that the genomic response to selection can involve a large number of selected SNPs that show unexpectedly complex evolutionary trajectories, possibly due to nonadditive effects. PMID:22726122

Orozco-terWengel, Pablo; Kapun, Martin; Nolte, Viola; Kofler, Robert; Flatt, Thomas; Schlötterer, Christian

2012-01-01

121

Selection of the Mars Science Laboratory landing site  

USGS Publications Warehouse

The selection of Gale crater as the Mars Science Laboratory landing site took over five years, involved broad participation of the science community via five open workshops, and narrowed an initial >50 sites (25 by 20 km) to four finalists (Eberswalde, Gale, Holden and Mawrth) based on science and safety. Engineering constraints important to the selection included: (1) latitude (±30°) for thermal management of the rover and instruments, (2) elevation (<-1 km) for sufficient atmosphere to slow the spacecraft, (3) relief of <100-130 m at baselines of 1-1000 m for control authority and sufficient fuel during powered descent, (4) slopes of <30° at baselines of 2-5 m for rover stability at touchdown, (5) moderate rock abundance to avoid impacting the belly pan during touchdown, and (6) a radar-reflective, load-bearing, and trafficable surface that is safe for landing and roving and not dominated by fine-grained dust. Science criteria important for the selection include the ability to assess past habitable environments, which include diversity, context, and biosignature (including organics) preservation. Sites were evaluated in detail using targeted data from instruments on all active orbiters, and especially Mars Reconnaissance Orbiter. All of the final four sites have layered sedimentary rocks with spectral evidence for phyllosilicates that clearly address the science objectives of the mission. Sophisticated entry, descent and landing simulations that include detailed information on all of the engineering constraints indicate all of the final four sites are safe for landing. Evaluation of the traversabilty of the landing sites and target “go to” areas outside of the ellipse using slope and material properties information indicates that all are trafficable and “go to” sites can be accessed within the lifetime of the mission. In the final selection, Gale crater was favored over Eberswalde based on its greater diversity and potential habitability.

Golombek, M.; Grant, J.; Kipp, D.; Vasavada, A.; Kirk, Randolph L.; Fergason, Robin L.; Bellutta, P.; Calef, F.; Larsen, K.; Katayama, Y.; Huertas, A.; Beyer, R.; Chen, A.; Parker, T.; Pollard, B.; Lee, S.; Hoover, R.; Sladek, H.; Grotzinger, J.; Welch, R.; Dobrea, E. Noe; Michalski, J.; Watkins, M.

2012-01-01

122

Selection of the Mars Science Laboratory Landing Site  

NASA Astrophysics Data System (ADS)

The selection of Gale crater as the Mars Science Laboratory landing site took over five years, involved broad participation of the science community via five open workshops, and narrowed an initial >50 sites (25 by 20 km) to four finalists (Eberswalde, Gale, Holden and Mawrth) based on science and safety. Engineering constraints important to the selection included: (1) latitude (±30°) for thermal management of the rover and instruments, (2) elevation (<-1 km) for sufficient atmosphere to slow the spacecraft, (3) relief of <100-130 m at baselines of 1-1000 m for control authority and sufficient fuel during powered descent, (4) slopes of <30° at baselines of 2-5 m for rover stability at touchdown, (5) moderate rock abundance to avoid impacting the belly pan during touchdown, and (6) a radar-reflective, load-bearing, and trafficable surface that is safe for landing and roving and not dominated by fine-grained dust. Science criteria important for the selection include the ability to assess past habitable environments, which include diversity, context, and biosignature (including organics) preservation. Sites were evaluated in detail using targeted data from instruments on all active orbiters, and especially Mars Reconnaissance Orbiter. All of the final four sites have layered sedimentary rocks with spectral evidence for phyllosilicates that clearly address the science objectives of the mission. Sophisticated entry, descent and landing simulations that include detailed information on all of the engineering constraints indicate all of the final four sites are safe for landing. Evaluation of the traversabilty of the landing sites and target "go to" areas outside of the ellipse using slope and material properties information indicates that all are trafficable and "go to" sites can be accessed within the lifetime of the mission. In the final selection, Gale crater was favored over Eberswalde based on its greater diversity and potential habitability.

Golombek, M.; Grant, J.; Kipp, D.; Vasavada, A.; Kirk, R.; Fergason, R.; Bellutta, P.; Calef, F.; Larsen, K.; Katayama, Y.; Huertas, A.; Beyer, R.; Chen, A.; Parker, T.; Pollard, B.; Lee, S.; Sun, Y.; Hoover, R.; Sladek, H.; Grotzinger, J.; Welch, R.; Noe Dobrea, E.; Michalski, J.; Watkins, M.

2012-09-01

123

Natural Selection Is a Sorting Process: What Does that Mean?  

ERIC Educational Resources Information Center

To learn why natural selection acts only on existing variation, students categorize processes as either creative or sorting. This activity helps students confront the misconception that adaptations evolve because species need them.

Price, Rebecca M.

2013-01-01

124

Agents with imperfect empathy may survive natural selection  

Microsoft Academic Search

Cultural transmission mechanisms which favor the direct transmission of the parents’ traits to their children may be adaptive to natural selection when opposed to mechanisms in which the parents choose for the offspring the highest fitness at any time.

Alberto Bisin; Thierry Verdier

2001-01-01

125

The Effect of Natural Selection on Phylogeny Reconstruction Algorithms  

Microsoft Academic Search

We study the effect of natural selection on the performance of phylogeny reconstruction algorithms using Avida, a software\\u000a platform that maintains a population of digital organisms (self-replicating computer programs) that evolve subject to natural\\u000a selection, mutation, and drift. We compare the performance of neighbor-joining and maximum parsimony algorithms on these Avida\\u000a populations to the performance of the same algorithms on

Dehua H. Hang; Charles Ofria; Thomas M. Schmidt; Eric Torng

2003-01-01

126

Natural Selection: A Case for the Counterfactual Approach  

Microsoft Academic Search

This paper investigates the conception of causation required in order to make sense of natural selection as a causal explanation\\u000a of changes in traits or allele frequencies. It claims that under a counterfactual account of causation, natural selection\\u000a is constituted by the causal relevance of traits and alleles to the variation in traits and alleles frequencies. The “statisticalist”\\u000a view of

Philippe Huneman

127

Laboratory demonstration of real time frame selection with Magellan AO  

NASA Astrophysics Data System (ADS)

The Magellan AO system combines a pyramid wavefront sensor and high-order adaptive secondary mirror, and will see first light on the Magellan Clay telescope in November 2012. With a 24 cm projected actuator pitch, this powerful system will enable good correction in the optical (0.5 to 1 ?m). Realistic laboratory testing has produced Strehl ratios greater than 40% in i’ (0.765 ?m) on bright simulated stars. On fainter stars our visible AO camera, VisAO, will work in the partially corrected regime with only short moments of good correction. We have developed a form of lucky imaging, called real time frame selection, which uses a fast shutter to block moments of bad correction, and quickly opens the shutter when the correction is good, enabling long integrations on a conventional CCD while maximizing Strehl ratio and resolution. The decision to open or shut is currently based on reconstructed WFS telemetry. Here we report on our implementation and testing of this technique in the Arcetri test tower in Florence, Italy, where we showed that long exposure i’ Strehl could be improved from 16% to 26% when the selection threshold was set to the best 10% of instantaneous Strehl.

Males, Jared R.; Close, Laird M.; Kopon, Derek; Quiros-Pacheco, Fernando; Riccardi, Armando; Xompero, Marco; Puglisi, Alfio; Gasho, Victor; Morzinski, Katie M.; Follette, Katherine B.

2012-07-01

128

Fitness, Probability and the Principles of Natural Selection  

Microsoft Academic Search

We argue that a fashionable interpretation of the theory of natural selection as a claim exclusively about populations is mistaken. The interpretation rests on adopting an analysis of fitness as a probabilistic propensity which cannot be substantiated, draws parallels to thermodynamics which are without foundations, and fails to do justice to the fundamental distinction between drift and selection. This distinction

FRÉDÉRIC BOUCHARD; ALEX ROSENBERG; STATION CENTRE-VILLE

2004-01-01

129

Natural selection and divergence in mate preference during speciation  

Microsoft Academic Search

Sexual isolation can evolve due to natural selection against hybrids (reinforcement). However, many different forms of hybrid\\u000a dysfunction, and selective processes that do not involve hybrids, can contribute to the evolution of sexual isolation. Here\\u000a we review how different selective processes affect the evolution of sexual isolation, describe approaches for distinguishing\\u000a among them, and assess how they contribute to variation

Patrik Nosil; Bernard J. Crespi; Regine Gries; Gerhard Gries

2007-01-01

130

A network of schools for a natural hazard laboratory  

NASA Astrophysics Data System (ADS)

With the Department of Education of the Aosta Valley - Italy - I have been engaged, for a long time, to promote initiatives with the aim to disseminate scientific culture in order to support teachers in their work and to foster in students the acquisition of scientific knowledge, skills and literacy, as required by the international standards of OECD and TIMSS. For this purpose, a network including all schools has been built, with the aim to promote the co-construction of standards of knowledge, a shared and effective use of resources and tools, of good practices, particularly those experiences based on a deductive, constructivist and Inquiry based approach. SCIENCE IN THE NETWORK: a Regional Science Centre has been built, with the aim to share experimental protocols and scientific instruments, to rationalize expenses, with hands-on individual workstations, high level instruments, but also rough materials. Students of all classes and all ages learn how to use scientific instruments, as required by an "up to date" school. A NETWORK OF PROJECTS: A NATURAL HAZARDS LABORATORY, with many others, has been set up, in cooperation with all regional stakeholders, with the aim to promote in all the schools a shared knowledge of the landscape, of its geological and geomorphologic evolution, with the aim to spread the culture of natural hazards and of prevention, to increase the sensitivity for an intelligent, supportive and sustainable use of the territory, environmentally aware of the natural dynamics. Students can experiment, using technical or wooden made instruments, the effects that natural phenomena, action of waters, ice and gravity can product on outcrops and landscape and to apply to local contest the relationship between the concept of hazard, risk and vulnerability.

Occhipinti, S.

2012-04-01

131

Natural selection and the genetics of adaptation in threespine stickleback  

PubMed Central

Growing knowledge of the molecular basis of adaptation in wild populations is expanding the study of natural selection. We summarize ongoing efforts to infer three aspects of natural selection—mechanism, form and history—from the genetics of adaptive evolution in threespine stickleback that colonized freshwater after the last ice age. We tested a mechanism of selection for reduced bony armour in freshwater by tracking genotype and allele frequency changes at an underlying major locus (Ectodysplasin) in transplanted stickleback populations. We inferred disruptive selection on genotypes at the same locus in a population polymorphic for bony armour. Finally, we compared the distribution of phenotypic effect sizes of genes underlying changes in body shape with that predicted by models of adaptive peak shifts following colonization of freshwater. Studies of the effects of selection on genes complement efforts to identify the molecular basis of adaptive differences, and improve our understanding of phenotypic evolution. PMID:20643737

Schluter, Dolph; Marchinko, Kerry B.; Barrett, R. D. H.; Rogers, Sean M.

2010-01-01

132

Variability and Selection in Natural Populations of Wood Lice  

NSDL National Science Digital Library

This resource is a manual for instructing a laboratory exercise in evolutionary biology. Students are introduced to relationships between variation and selection. They conduct hands-on artificial predation studies, which allow them to observe and measure physical, morphological, and behavioral variations among wood lice populations.

Rudi C. Berkelhamer (University of California at Irvine; )

1998-01-01

133

Reasoning and Natural Selection LEDA COSMIDES, JOHN TOOBY, Center for Advanced Study in  

E-print Network

Reasoning and Natural Selection LEDA COSMIDES, JOHN TOOBY, Center for Advanced Study of natural selection because it served an adaptive function Adaptive Contributing to the eventual reproduc Cognitive psychology Study of how humans and other animals process information Natural selection

Cosmides, Leda

134

Natural selection on testosterone production in a wild songbird population.  

PubMed

Because of their role in mediating life-history trade-offs, hormones are expected to be strongly associated with components of fitness; however, few studies have examined how natural selection acts on hormonal variation in the wild. In a songbird, the dark-eyed junco (Junco hyemalis), field experiments have shown that exogenous testosterone alters individuals' resolution of the survival-reproduction trade-off, enhancing reproduction at the expense of survival. Here we used standardized injections of gonadotropin-releasing hormone (GnRH) to assay variation in the testosterone production of males. Using measurements of annual survival and reproduction, we found evidence of strong natural selection acting on GnRH-induced increases in testosterone. Opposite to what would be predicted from the survival-reproduction trade-off, patterns of selection via survival and reproduction were remarkably similar. Males with GnRH-induced testosterone production levels that were slightly above the population mean were more likely to survive and also produced more offspring, leading to strong stabilizing selection. Partitioning reproduction into separate components revealed positive directional selection via within-pair siring success and stabilizing selection via extrapair mating success. Our data represent the most complete demonstration of natural selection on hormones via multiple fitness components, and they complement previous experiments to illuminate testosterone's role in the evolution of life-history trade-offs. PMID:20394524

McGlothlin, Joel W; Whittaker, Danielle J; Schrock, Sara E; Gerlach, Nicole M; Jawor, Jodie M; Snajdr, Eric A; Ketterson, Ellen D

2010-06-01

135

Natural and sexual selection in a monogamous historical human population  

PubMed Central

Whether and how human populations exposed to the agricultural revolution are still affected by Darwinian selection remains controversial among social scientists, biologists, and the general public. Although methods of studying selection in natural populations are well established, our understanding of selection in humans has been limited by the availability of suitable datasets. Here, we present a study comparing the maximum strengths of natural and sexual selection in humans that includes the effects of sex and wealth on different episodes of selection. Our dataset was compiled from church records of preindustrial Finnish populations characterized by socially imposed monogamy, and it contains a complete distribution of survival, mating, and reproductive success for 5,923 individuals born 1760–1849. Individual differences in early survival and fertility (natural selection) were responsible for most variation in fitness, even among wealthier individuals. Variance in mating success explained most of the higher variance in reproductive success in males compared with females, but mating success also influenced reproductive success in females, allowing for sexual selection to operate in both sexes. The detected opportunity for selection is in line with measurements for other species but higher than most previous reports for human samples. This disparity results from biological, demographic, economic, and social differences across populations as well as from failures by most previous studies to account for variation in fitness introduced by nonreproductive individuals. Our results emphasize that the demographic, cultural, and technological changes of the last 10,000 y did not preclude the potential for natural and sexual selection in our species. PMID:22547810

Courtiol, Alexandre; Pettay, Jenni E.; Jokela, Markus; Rotkirch, Anna; Lummaa, Virpi

2012-01-01

136

Natural and sexual selection in a monogamous historical human population.  

PubMed

Whether and how human populations exposed to the agricultural revolution are still affected by Darwinian selection remains controversial among social scientists, biologists, and the general public. Although methods of studying selection in natural populations are well established, our understanding of selection in humans has been limited by the availability of suitable datasets. Here, we present a study comparing the maximum strengths of natural and sexual selection in humans that includes the effects of sex and wealth on different episodes of selection. Our dataset was compiled from church records of preindustrial Finnish populations characterized by socially imposed monogamy, and it contains a complete distribution of survival, mating, and reproductive success for 5,923 individuals born 1760-1849. Individual differences in early survival and fertility (natural selection) were responsible for most variation in fitness, even among wealthier individuals. Variance in mating success explained most of the higher variance in reproductive success in males compared with females, but mating success also influenced reproductive success in females, allowing for sexual selection to operate in both sexes. The detected opportunity for selection is in line with measurements for other species but higher than most previous reports for human samples. This disparity results from biological, demographic, economic, and social differences across populations as well as from failures by most previous studies to account for variation in fitness introduced by nonreproductive individuals. Our results emphasize that the demographic, cultural, and technological changes of the last 10,000 y did not preclude the potential for natural and sexual selection in our species. PMID:22547810

Courtiol, Alexandre; Pettay, Jenni E; Jokela, Markus; Rotkirch, Anna; Lummaa, Virpi

2012-05-22

137

Sexual selection, natural selection and the evolution of dimorphic coloration and ornamentation in agamid lizards.  

PubMed Central

Both sexual selection and natural selection can influence the form of dimorphism in secondary sexual traits. Here, we used a comparative approach to examine the relative roles of sexual selection and natural selection in the evolution of sexually dimorphic coloration (dichromatism) and ornamentation in agamid lizards. Sexual dimorphism in head and body size were used as indirect indicators of sexual selection, and habitat type (openness) as an index of natural selection. We examined separately the dichromatism of body regions "exposed to" and "concealed from" visual predators, because these body regions are likely to be subject to different selection pressures. Dichromatism of "exposed" body regions was significantly associated with habitat type: males were typically more conspicuously coloured than females in closed habitats. By contrast, dichromatism of "concealed" body regions and ornament dimorphism were positively associated with sexual size dimorphism (SSD). When we examined male and female ornamentation separately, however, both were positively associated with habitat openness in addition to snout-vent length and head SSD. These results suggest that natural selection constrains the evolution of elaborate ornamentation in both sexes as well as sexual dichromatism of body regions exposed to visual predators. By contrast, dichromatism of "concealed" body regions and degree of ornament dimorphism appear to be driven to a greater degree by sexual selection. PMID:15539350

Stuart-Fox, Devi M.; Ord, Terry J.

2004-01-01

138

Aspergillus flavus dose–response curves to selected natural and synthetic antimicrobials  

Microsoft Academic Search

The effects of selected concentrations of antimicrobials from natural (vanillin, thymol, eugenol, carvacrol or citral) or synthetic (potassium sorbate or sodium benzoate) origin on Aspergillus flavus lag time inoculated in laboratory media formulated at water activity (aw) 0.99 and pH 4.5 or 3.5, were evaluated. Time to detect a colony with a diameter >0.5 mm was determined. Mold response was

Aurelio López-Malo; Stella M Alzamora; Enrique Palou

2002-01-01

139

Fitness landscape of Atlantic cod shaped by harvest selection and natural selection  

Microsoft Academic Search

Harvesting may lead to evolutionary changes in life histories on a contemporary time scale, changes that could be maladaptive\\u000a in natural contexts. However, our understanding of the strength and direction of harvest-induced selection versus natural\\u000a selection is still limited, partly due to the difficulty of tracking the fate of individuals in the wild. Here, we present\\u000a direct estimates of harvest

Esben Moland Olsen; Even Moland

2011-01-01

140

Molecular Coevolution and the Three-Dimensionality of Natural Selection  

Microsoft Academic Search

\\u000a Natural selection is the force driving evolution and therefore much effort has been invested in the deciphering and understanding\\u000a of the main mechanisms underlying such a force. Because of the main implications of identifying selective processes in proteins\\u000a and the perspectives for defining functional\\/structural amino acid sites in protein structures, many models have been devised\\u000a in order to search for

Mario A. Fares; Christina Toft

141

MICHAEL G. RYAN Natural Resource Ecology Laboratory Colorado State University, Fort Collins, CO 80523-1499  

E-print Network

MICHAEL G. RYAN Natural Resource Ecology Laboratory Colorado State University, Fort Collins, CO Ecology Laboratory, Colorado State University, Fort Collins, CO. Senior Research Scientist, 2012-present. Research, teaching and graduate student advising. Rocky Mountain Research Station, USDA, Fort Collins, CO

MacDonald, Lee

142

Measuring natural selection on genotypes and phenotypes in the wild.  

PubMed

A complete understanding of the role of natural selection in driving evolutionary change requires accurate estimates of the strength of selection acting in the wild. Accordingly, several approaches using a variety of data-including patterns of DNA variability, spatial and temporal changes in allele frequencies, and fitness estimates-have been developed to identify and quantify selection on both genotypes and phenotypes. Here, we review these approaches, drawing on both recent and classic examples to illustrate their utility and limitations. We then argue that by combining estimates of selection at multiple levels-from individual mutations to phenotypes-and at multiple timescales-from ecological to evolutionary-with experiments that demonstrate why traits are under selection, we can gain a much more complete picture of the adaptive process. PMID:20413707

Linnen, C R; Hoekstra, H E

2009-01-01

143

Measuring Natural Selection on Genotypes and Phenotypes in the Wild  

PubMed Central

A complete understanding of the role of natural selection in driving evolutionary change requires accurate estimates of the strength of selection acting in the wild. Accordingly, several approaches utilizing a variety of data—including patterns of DNA variability, spatial and temporal changes in allele frequencies, and fitness estimates—have been developed to identify and quantify selection on both genotypes and phenotypes. Here, we review these approaches, drawing on both recent and classic examples to illustrate their utility and limitations. We then argue that by combining estimates of selection at multiple levels—from individual mutations to phenotypes—and at multiple timescales—from ecological to evolutionary—with experiments that demonstrate why traits are under selection, we can gain a much more complete picture of the adaptive process. PMID:20413707

Linnen, Catherine R.; Hoekstra, Hopi E.

2013-01-01

144

Natural selection on floral volatile production in Penstemon digitalis  

PubMed Central

Natural selection is thought to have shaped the evolution of floral scent; however, unlike other floral characters, we have a rudimentary knowledge of how phenotypic selection acts on scent. We found that floral scent was under stronger selection than corolla traits such as flower size and flower color in weakly scented Penstemon digitalis. Our results suggest that to understand evolution in floral phenotypes, including scent in floral selection, studies are crucial. For P. digitalis, linalool was the direct target of selection in the scent bouquet. Therefore, we determined the enantiomeric configuration of linalool because interacting insects may perceive the enantiomers differentially. We found that P. digitalis produces only (S)-(+)-linalool and, more interestingly, it is also taken up into the nectar. Because the nectar is scented and flavored with (S)-(+)-linalool, it may be an important cue for pollinators visiting P. digitalis flowers. PMID:23221753

Parachnowitsch, Amy L.; Burdon, Rosalie C. F.; Raguso, Robert A.; Kessler, André

2013-01-01

145

The Slumgullion Natural Laboratory for Observing Slip Phenomena  

NASA Astrophysics Data System (ADS)

Many natural systems release stresses by failure and sliding across surfaces; examples include landslides, glaciers, crustal- and plate-scale faults. Observational advances continue to reveal diversity in the seismic signals associated with fault slip and how such stress relaxation can occur, even on a single fault system. A particularly rich example are the episodes of slow fault slip near major subduction and transform plate boundaries that manifest as geodetically observed aseismic deformation abetted by a family of seismic signals depleted in high-frequencies relative to those from earthquakes (named ‘episodic tremor and slip’ or ETS). While the driving forces and scales differ, there are striking parallels between some observations and models of ETS and of landslide behaviors; e.g. in both, postulated key controls include rate-dependent friction and strength modulated by pore-pressure changes, dilatancy during rapid shear, and subsequent consolidation. To explore common features and the underlying processes we are studying the Slumgullion landslide, an ideal natural laboratory for observing fault slip and associated seismic and aseismic phenomena. Unlike crustal- or plate-scale studies significant deformation can be measured within a single field season, because the Slumgullion moves at average rates of cm/day. Moreover, pore pressures, displacements, material properties, and environmental variables may be measured directly and continuously at several locations on the landslide (albeit not at the basal sliding surface). We have just completed a field experiment on the Slumgullion to test several hypotheses, particularly that slip along the basal surface and side-bounding faults occurs with comparable richness of aseismic and seismic modes as crustal- and plate-scale boundaries. To do so from August 18-26, 2009 we continuously monitored the displacement-field using a robotic electronic displacement meter and the seismic radiation with 88 vertical-component seismographs [see Bodin et al., companion abstract]. Although we have only begun examining the data thus far, the seismic data contain an abundance of network-wide coherent signals with an amazing variety of characteristics. Significant unsteady movement in the displacement field is evident in the geodetic data, as well as fluctuations in the pore-pressures and relevant environmental parameters. Schulz et al. (companion abstract) presents initial landslide observations. We will form and present implications for understanding the likely mechanisms of failure and slip within natural systems.

Gomberg, J. S.; Schulz, W. H.; Bodin, P.; Kean, J. W.; Wang, G.; Coe, J. A.; MacQueen, P.; Foster, K.; Creager, K.

2009-12-01

146

Peppered Moth Scavenger Hunt Activity Standard: Adaptation and natural selection.  

E-print Network

Peppered Moth Scavenger Hunt Activity Grade: 4th Standard: Adaptation and natural selection. Supplements: Peppered Moth introduction slides http://www.techapps.net/interactives/pepperMoths.swf Materials to trace Sticky tape to stick moths onto surfaces Overview 1. Divide class into 2 groups 2. Each kid

147

Using Different Examples of Natural Selection When Teaching Biology.  

ERIC Educational Resources Information Center

Describes the following examples of natural selection for use in science instruction: sickle-cell anemia and human beings, clogged crabs, the rounding of the human head, shell color in land snails, pollinator behavior and flower color, copper tolerance in a grass, lizards and quick change, and Darwin's finches. (PR)

Perry, Robert T.

1993-01-01

148

NATURAL SELECTION, THE HUMAN GENOME AND THE IDEA OF RACE  

E-print Network

1 NATURAL SELECTION, THE HUMAN GENOME AND THE IDEA OF RACE Robert Pollack, PhD This briefing paper are members of one species, all concepts of "Race" that place one set of humans aside as in some way more of imaginary, false notions such as "Race" is an example of the most remarkable characteristic of all members

Pollack, Robert

149

Signatures of natural selection in the human genome  

Microsoft Academic Search

During their dispersal from Africa, our ancestors were exposed to new environments and diseases. Those who were better adapted to local conditions passed on their genes, including those conferring these benefits, with greater frequency. This process of natural selection left signatures in our genome that can be used to identify genes that might underlie variation in disease resistance or drug

Michael Bamshad; Stephen P. Wooding

2003-01-01

150

Designing an auction protocol under asymmetric information on nature's selection  

Microsoft Academic Search

Internet auctions are becoming an especially popular part of Electronic Commerce and auction protocols have been studied very widely in the field of multi-agent systems and AI. However, correctly judging the quality of auctioned goods is often difficult for non-experts (amateurs), in particular, on the Internet auctions. In this paper, we formalize such a situation so that Nature selects the

Takayuki Ito; Makoto Yokoo; Shigeo Matsubara

2002-01-01

151

Natural Selection on Functional Modules, a Genome-Wide Analysis  

Microsoft Academic Search

Classically, the functional consequences of natural selection over genomes have been analyzed as the compound effects of individual genes. The current paradigm for large-scale analysis of adaptation is based on the observed significant deviations of rates of individual genes from neutral evolutionary expectation. This approach, which assumed independence among genes, has not been able to identify biological functions significantly enriched

François Serra; Leonardo Arbiza; Joaquín Dopazo; Hernán Dopazo

2011-01-01

152

Darwin and Natural Selection One of the most  

E-print Network

;Charles Darwin in 1837, age 28, after voyage of the Beagle #12;Age 40 Age 45 #12;Charles Darwin, age 60Darwin and Natural Selection #12;One of the most famous books of science. #12;Darwin's home, Down House, in England #12;Darwin's study at his home Down House #12;Voyage of HMS Beagle, 1831- 1836 #12

Kammer, Thomas

153

Ocean waves, nearshore ecology, and natural selection Mark W. Denny*  

E-print Network

-1 Ocean waves, nearshore ecology, and natural selection Mark W. Denny* Stanford University and Helmuth 2002). At high tide, ocean waves break on the shore, imposing large hydrodynamic forces, Intertidal communities, Lift, Wave theory Abstract Although they are subjected to one of the most stressful

Denny, Mark

154

Natural Selection and Genetic Drift in Protein Polymorphism  

Microsoft Academic Search

THE Kimura theory1 that protein polymorphism is mainly due to random genetic drift acting on a number of neutral isoalleles has been recently discussed by many authors2-4. The electrophoretic study of populations of the same species having different geographical origin and showing great fluctuations in number offers possibilities for testing the relative importance of natural selection and genetic drift in

Luciano Bullini; MARIO COLUZZI

1972-01-01

155

Evolution of Behavior by Density-Dependent Natural Selection  

Microsoft Academic Search

Theories of density-dependent natural selection predict that evolution should favor those genotypes with the highest per capita rates of population growth under the current density conditions. These theories are silent about the mechanisms that may give rise to these increases in density-dependent growth rates. We have observed the evolution of six populations of Drosophila melanogaster recently placed in crowded environments

Pingzhong Guo; Laurence D. Mueller; Francisco J. Ayala

1991-01-01

156

Assessing the effect of natural selection in malaria parasites  

Microsoft Academic Search

There are few concepts that have been used across disciplines; one of them is natural selection. The impact that this process has on parasite genetic diversity is reviewed here by discussing examples on drug resistance and vaccine antigens. Emphasis is made on how mechanisms need to be addressed rather than associations, and how such investigations were out of reach of

Ananias A. Escalante; Omar E. Cornejo; Ascanio Rojas; Venkatachalam Udhayakumar; Altaf A. Lal

2004-01-01

157

Can There be A Priori Causal Models of Natural Selection?  

Microsoft Academic Search

Sober 2011 argues that, contrary to Hume, some causal statements can be known a priori to be true—notably, some ‘would promote’ statements figuring in causal models of natural selection. We find Sober's argument unconvincing. We regard the Humean thesis as denying that causal explanations contain any a priori knowable statements specifying certain features of events to be causally relevant. We

Marc Lange; Alexander Rosenberg

2011-01-01

158

Natural selection vs. random drift: evidence from temporal variation in allele frequencies in nature.  

PubMed

We have obtained monthly samples of two species, Drosophila pseudoobscura and Drosophila persimilis, in a natural population from Napa County, California. In each species, about 300 genes have been assayed by electrophoresis for each of seven enzyme loci in each monthly sample from March 1972 to June 1975. Using statistical methods developed for the purpose, we have examined whether the allele frequencies at different loci vary in a correlated fashion. The methods used do not detect natural selection when it is deterministic (e.g., overdominance or directional selection), but only when alleles at different loci vary simultaneously in response to the same environmental variations. Moreover, only relatively large fitness differences (of the order of 15%) are detectable. We have found strong evidence of correlated allele frequency variation in 13-20% of the cases examined. We interpret this as evidence that natural selection plays a major role in the evolution of protein polymorphisms in nature. PMID:4054608

Mueller, L D; Barr, L G; Ayala, F J

1985-11-01

159

Ontogenetic selection on hatchery salmon in the wild: natural selection on artificial phenotypes  

PubMed Central

Captive rearing often alters the phenotypes of organisms that are destined for release into the wild. Natural selection on these unnatural phenotypes could have important consequences for the utility of captive rearing as a restoration approach. We show that normal hatchery practices significantly advance the development of endangered Atlantic salmon (Salmo salar) fry by 30+ days. As a result, hatchery fry might be expected to face strong natural selection resulting from their developmental asynchrony. We investigated patterns of ontogenetic selection acting on hatchery produced salmon fry by experimentally manipulating fry development stage at stocking. Contrary to simple predictions, we found evidence for strong stabilizing selection on the ontogeny of unfed hatchery fry, with weaker evidence for positive directional selection on the ontogeny of fed fry. These selection patterns suggest a seasonally independent tradeoff between abiotic or biotic selection favoring advanced development and physiological selection linked to risk of starvation in unfed fry. We show, through a heuristic exercise, how such selection on ontogeny may exacerbate problems in restoration efforts by impairing fry productivity and reducing effective population sizes by 13–81%. PMID:25567929

Bailey, Michael M; Lachapelle, Kevin A; Kinnison, Michael T

2010-01-01

160

Survey and analysis of materials research and development at selected federal laboratories  

SciTech Connect

This document presents the results of an effort to transfer existing, but relatively unknown, materials R and D from selected federal laboratories to industry. More specifically, recent materials-related work at seven federal laboratories potentially applicable to improving process energy efficiency and overall productiviy in six energy-intensive manufacturing industries was evaluated, catalogued, and distributed to industry representatives to gauge their reaction. Laboratories surveyed include: Air Force Wright Aeronautical Laboratories Material Laboratory (AFWAL). Pacific Northwest Laboratory (PNL), National Aeronautics and Space Administration Marshall Flight Center (NASA Marshall), Oak Ridge National Laboratory (ORNL), Brookhaven National Laboratory (BNL), Idaho National Engineering Laboratory (INEL), and Jet Propulsion Laboratory (JPL). Industries included in the effort are: aluminum, cement, paper and allied products, petroleum, steel and textiles.

Reed, J.E.; Fink, C.R.

1984-04-01

161

Using natural laboratories and modeling to decipher lithospheric rheology  

NASA Astrophysics Data System (ADS)

Rheology is obviously important for geodynamic modeling but at the same time rheological parameters appear to be least constrained. Laboratory experiments give rather large ranges of rheological parameters and their scaling to nature is not entirely clear. Therefore finding rheological proxies in nature is very important. One way to do that is finding appropriate values of rheological parameter by fitting models to the lithospheric structure in the highly deformed regions where lithospheric structure and geologic evolution is well constrained. Here I will present two examples of such studies at plate boundaries. One case is the Dead Sea Transform (DST) that comprises a boundary between African and Arabian plates. During the last 15- 20 Myr more than 100 km of left lateral transform displacement has been accumulated on the DST and about 10 km thick Dead Sea Basin (DSB) was formed in the central part of the DST. Lithospheric structure and geological evolution of DST and DSB is rather well constrained by a number of interdisciplinary projects including DESERT and DESIRE projects leaded by the GFZ Potsdam. Detailed observations reveal apparently contradictory picture. From one hand widespread igneous activity, especially in the last 5 Myr, thin (60-80 km) lithosphere constrained from seismic data and absence of seismicity below the Moho, seem to be quite natural for this tectonically active plate boundary. However, surface heat flow of less than 50-60mW/m2 and deep seismicity in the lower crust ( deeper than 20 km) reported for this region are apparently inconsistent with the tectonic settings specific for an active continental plate boundary and with the crustal structure of the DSB. To address these inconsistencies which comprise what I call the "DST heat-flow paradox", a 3D numerical thermo-mechanical model was developed operating with non-linear elasto-visco-plastic rheology of the lithosphere. Results of the numerical experiments show that the entire set of observations for the DSB can be explained within the classical pull-apart model assuming that (1) the lithosphere has been thermally eroded at about 20 Ma, just before the active faulting at the DST, and (2) the uppermost mantle in the region have relatively weak rheology consistent with the experimental data for wet olivine or pyroxenite. Another example is modeling of the collision of India and Eurasia in Tibet. Our recent thermo-mechanical model (see abstract by Tympel et al) reproduce well many important features of this orogeny, including observed convergence and distance of underthrusting of Indian lithosphere beneath Tibet, if long-term friction at India-Eurasia interface is about 0.04- 0.05, which is typical for oceanic subduction zones, but is unexpected low for continental setting.

Sobolev, Stephan

2013-04-01

162

Preventing Alzheimer's disease by means of natural selection  

PubMed Central

The amyloid cascade model for the origin of sporadic forms of Alzheimer's disease (AD) posits that the imbalance in the production and clearance of beta-amyloid is a necessary condition for the disease. A competing theory called the entropic selection hypothesis asserts that the primary cause of sporadic AD is age-induced mitochondrial dysregulation and the following cascade of events: (i) metabolic reprogramming—the upregulation of oxidative phosphorylation in compensation for insufficient energy production in neurons, (ii) natural selection—competition between intact and reprogrammed neurons for energy substrates and (iii) propagation—the spread of the disease due to the selective advantage of neurons with upregulated metabolism. Experimental studies to evaluate the predictions of the amyloid cascade model are being continually retuned to accommodate conflicts of the predictions with empirical data. Clinical trials of treatments for AD based on anti-amyloid therapy have been unsuccessful. We contend that these anomalies and failures stem from a fundamental deficit of the amyloid hypothesis: the model derives from a nuclear-genomic perspective of sporadic AD and discounts the bioenergetic processes that characterize the progression of most age-related disorders. In this article, we review the anomalies of the amyloid model and the theoretical and empirical support for the entropic selection theory. We also discuss the new therapeutic strategies based on natural selection which the model proposes. PMID:25551134

Demetrius, Lloyd A.; Driver, Jane A.

2015-01-01

163

Preventing Alzheimer's disease by means of natural selection.  

PubMed

The amyloid cascade model for the origin of sporadic forms of Alzheimer's disease (AD) posits that the imbalance in the production and clearance of beta-amyloid is a necessary condition for the disease. A competing theory called the entropic selection hypothesis asserts that the primary cause of sporadic AD is age-induced mitochondrial dysregulation and the following cascade of events: (i) metabolic reprogramming—the upregulation of oxidative phosphorylation in compensation for insufficient energy production in neurons, (ii) natural selection—competition between intact and reprogrammed neurons for energy substrates and (iii) propagation—the spread of the disease due to the selective advantage of neurons with upregulated metabolism. Experimental studies to evaluate the predictions of the amyloid cascade model are being continually retuned to accommodate conflicts of the predictions with empirical data. Clinical trials of treatments for AD based on anti-amyloid therapy have been unsuccessful. We contend that these anomalies and failures stem from a fundamental deficit of the amyloid hypothesis: the model derives from a nuclear-genomic perspective of sporadic AD and discounts the bioenergetic processes that characterize the progression of most age-related disorders. In this article, we review the anomalies of the amyloid model and the theoretical and empirical support for the entropic selection theory. We also discuss the new therapeutic strategies based on natural selection which the model proposes. PMID:25551134

Demetrius, Lloyd A; Driver, Jane A

2015-01-01

164

Genome-wide polymorphisms show unexpected targets of natural selection  

PubMed Central

Natural selection can act on all the expressed genes of an individual, leaving signatures of genetic differentiation or diversity at many loci across the genome. New power to assay these genome-wide effects of selection comes from associating multi-locus patterns of polymorphism with gene expression and function. Here, we performed one of the first genome-wide surveys in a marine species, comparing purple sea urchins, Strongylocentrotus purpuratus, from two distant locations along the species' wide latitudinal range. We examined 9112 polymorphic loci from upstream non-coding and coding regions of genes for signatures of selection with respect to gene function and tissue- and ontogenetic gene expression. We found that genetic differentiation (FST) varied significantly across functional gene classes. The strongest enrichment occurred in the upstream regions of E3 ligase genes, enzymes known to regulate protein abundance during development and environmental stress. We found enrichment for high heterozygosity in genes directly involved in immune response, particularly NALP genes, which mediate pro-inflammatory signals during bacterial infection. We also found higher heterozygosity in immune genes in the southern population, where disease incidence and pathogen diversity are greater. Similar to the major histocompatibility complex in mammals, balancing selection may enhance genetic diversity in the innate immune system genes of this invertebrate. Overall, our results show that how genome-wide polymorphism data coupled with growing databases on gene function and expression can combine to detect otherwise hidden signals of selection in natural populations. PMID:21993504

Pespeni, Melissa H.; Garfield, David A.; Manier, Mollie K.; Palumbi, Stephen R.

2012-01-01

165

Using David Lack's Observations of Finch Beak Size to Teach Natural Selection & the Nature of Science  

ERIC Educational Resources Information Center

One of the key aspects of natural selection is competition, yet the concept of competition is not necessarily emphasized in explanations of natural selection. Because of this, we developed an activity for our class that focuses on competition and provides an example of the effects of competition on natural selection. This hands-on activity models…

Bierema, Andrea M.-K.; Rudge, David W.

2014-01-01

166

University of Florida Natural Area Teaching Laboratory 2013 NATL Minigrant Program  

E-print Network

University of Florida Natural Area Teaching Laboratory 2013 NATL Minigrant Program Proposer Chris collected within the University of Florida's Natural Area Teaching Laboratory Project summary- Mosquitoes active collection technique will be a sweep net purchased from Bioquip (http://www.bioquip.com/search/DispProduct.asp

Slatton, Clint

167

Compactifying de Sitter Naturally Selects a Small Cosmological Constant  

E-print Network

We study compactifications of $D$-dimensional de Sitter space with a $q$-form flux down to $D-Nq$ dimensions. We show that for $(N-1)(q-1)\\geq 2$ there are double-exponentially or even infinitely many compact de Sitter vacua, and that their effective cosmological constants accumulate at zero. This population explosion of $\\Lambda \\ll 1$ de Sitters arises by a mechanism analogous to natural selection.

Adam R. Brown; Alex Dahlen; Ali Masoumi

2014-11-29

168

Natural selection shaped regional mtDNA variation in humans  

Microsoft Academic Search

Human mtDNA shows striking regional variation, traditionally attributed to genetic drift. However, it is not easy to account for the fact that only two mtDNA lineages (M and N) left Africa to colonize Eurasia and that lineages A, C, D, and G show a 5-fold enrichment from central Asia to Siberia. As an alternative to drift, natural selection might have

Dan Mishmar; Eduardo Ruiz-Pesini; Pawel Golik; Vincent Macaulay; Andrew G. Clark; Seyed Hosseini; Martin Brandon; Kirk Easley; Estella Chen; Michael D. Brown; Rem I. Sukernik; Antonel Olckers; Douglas C. Wallace

2002-01-01

169

Quantifying evolution and natural selection in vertebrate noncoding sequence  

E-print Network

sequence that do not require the regions of interest 23 to code for proteins. These include searching for reductions in genetic diversity, high-frequency derived alleles, allele frequency differences between populations, and long haplotypes (reviewed... Quantifying evolution and natural selection in vertebrate noncoding sequence Michael Milner Hoffman Trinity College A dissertation submitted to the University of Cambridge for the degree of Doctor of Philosophy EMBL–European Bioinformatics Institute...

Hoffman, Michael M.

2008-07-08

170

Compactifying de Sitter space naturally selects a small cosmological constant  

NASA Astrophysics Data System (ADS)

We study compactifications of D -dimensional de Sitter space with a q -form flux down to D -N q dimensions. We show that for (N -1 )(q -1 )?2 there are double-exponentially or even infinitely many compact de Sitter vacua, and that their effective cosmological constants accumulate at zero. This population explosion of ? ?1 de Sitters arises by a mechanism analogous to natural selection.

Brown, Adam R.; Dahlen, Alex; Masoumi, Ali

2014-12-01

171

Crop domestication and its impact on naturally selected trophic interactions.  

PubMed

Crop domestication is the process of artificially selecting plants to increase their suitability to human requirements: taste, yield, storage, and cultivation practices. There is increasing evidence that crop domestication can profoundly alter interactions among plants, herbivores, and their natural enemies. Overall, little is known about how these interactions are affected by domestication in the geographical ranges where these crops originate, where they are sympatric with the ancestral plant and share the associated arthropod community. In general, domestication consistently has reduced chemical resistance against herbivorous insects, improving herbivore and natural enemy performance on crop plants. More studies are needed to understand how changes in morphology and resistance-related traits arising from domestication may interact with environmental variation to affect species interactions across multiple scales in agroecosystems and natural ecosystems. PMID:25341108

Chen, Yolanda H; Gols, Rieta; Benrey, Betty

2015-01-01

172

Evolutionary Ecology, 1990, 4, 290-297 Density-dependent natural selection does not  

E-print Network

Evolutionary Ecology, 1990, 4, 290-297 Density-dependent natural selection does not increase- dependent natural selection, or r- and K-selection, as it is often called (Boyce, 1984). Their discussion-dependent natural selection have identified density-dependent rates of population growth as the phenotype

Rose, Michael R.

173

Darwin's Principles of Divergence and Natural Selection: Why Fodor was Almost Right  

E-print Network

0 Darwin's Principles of Divergence and Natural Selection: Why Fodor was Almost Right Robert J. Richards University of Chicago Abstract Darwin maintained that the principles of natural selection of the principle of divergence to that of natural selection? Is it independent of selection, derivative

Richards, Robert J.

174

Networking of Icelandic Earth Infrastructures - Natural laboratories and Volcano Supersites  

NASA Astrophysics Data System (ADS)

The back-bone of Icelandic geoscientific research infrastructure is the country's permanent monitoring networks, which have been built up to monitor seismic and volcanic hazard and deformation of the Earth's surface. The networks are mainly focussed around the plate boundary in Iceland, particularly the two seismic zones, where earthquakes of up to M7.3 have occurred in centuries past, and the rift zones with over 30 active volcanic systems where a large number of powerful eruptions have occurred, including highly explosive ones. The main observational systems are seismic, strong motion, GPS and bore-hole strain networks, with the addition of more recent systems like hydrological stations, permanent and portable radars, ash-particle counters and gas monitoring systems. Most of the networks are owned by a handful of Icelandic institutions, but some are operated in collaboration with international institutions and universities. The networks have been in operation for years to decades and have recorded large volumes of research quality data. The main Icelandic infrastructures will be networked in the European Plate Observing System (EPOS). The plate boundary in the South Iceland seismic zone (SISZ) with its book-shelf tectonics and repeating major earthquakes sequences of up to M7 events, has the potential to be defined a natural laboratory within EPOS. Work towards integrating multidisciplinary data and technologies from the monitoring infrastructures in the SISZ with other fault regions has started in the FP7 project NERA, under the heading of Networking of Near-Fault Observatories. The purpose is to make research-quality data from near-fault observatories available to the research community, as well as to promote transfer of knowledge and techical know-how between the different observatories of Europe, in order to create a network of fault-monitoring networks. The seismic and strong-motion systems in the SISZ are also, to some degree, being networked nationally to strengthen their early warning capabilities. In response to the far-reaching dispersion of ash from the 2010 Eyjafjallajökull eruption and subsequent disturbance to European air-space, the instrumentation of the Icelandic volcano observatory was greatly improved in number and capability to better monitor sub-surface volcanic processes as well as the air-borne products of eruptions. This infrastructure will also be networked with other European volcano observatories in EPOS. Finally the Icelandic EPOS team, together with other European collaborators, has responded to an FP7 call for the establishment of an Icelandic volcano supersite, where land- and space-based data will be made available to researchers and hazard managers, in line with the implementation plan of the GEO. The focus of the Icelandic volcano supersite are the active volcanoes in Iceland's Eastern volcanic zone.

Vogfjörd, K. S.; Sigmundsson, F.; Hjaltadóttir, S.; Björnsson, H.; Arason, Ø.; Hreinsdóttir, S.; Kjartansson, E.; Sigbjörnsson, R.; Halldórsson, B.; Valsson, G.

2012-04-01

175

Signatures of selection in natural populations adapted to chronic pollution  

PubMed Central

Background Populations of the teleost fish Fundulus heteroclitus appear to flourish in heavily polluted and geographically separated Superfund sites. Populations from three Superfund sites (New Bedford Harbor, MA, Newark Bay, NJ, and Elizabeth River, VA) have independently evolved adaptive resistance to chemical pollutants. In these polluted populations, natural selection likely has altered allele frequencies of loci that affect fitness or that are linked to these loci. The aim of this study was to identify loci that exhibit non-neutral behavior in the F. heteroclitus genome in polluted populations versus clean reference populations. Results To detect signatures of natural selection and thus identify genetic bases for adaptation to anthropogenic stressors, we examined allele frequencies for many hundreds of amplified fragment length polymorphism markers among populations of F. heteroclitus. Specifically, we contrasted populations from three Superfund sites (New Bedford Harbor, MA, Newark Bay, NJ, and Elizabeth River, VA) to clean reference populations flanking the polluted sites. When empirical FST values were compared to a simulated distribution of FST values, 24 distinct outlier loci were identified among pairwise comparisons of pollutant impacted F. heteroclitus populations and both surrounding reference populations. Upon removal of all outlier loci, there was a strong correlation (R2 = 0.79, p < 0.0001) between genetic and geographical distance. This apparently neutral evolutionary pattern was not evident when outlier loci were included (R2 = 0.092, p = 0.0721). Two outlier loci were shared between New Bedford Harbor and Elizabeth River populations, and two different loci were shared between Newark Bay and Elizabeth River populations. Conclusion In total, 1% to 6% of loci are implicated as being under selection or linked to areas of the genome under selection in three F. heteroclitus populations that reside in polluted estuaries. Shared loci among polluted sites indicate that selection may be acting on multiple loci involved in adaptation, and loci shared between polluted sites potentially are involved in a generalized adaptive response. PMID:18847479

2008-01-01

176

Implications of the Reduction Principle for Cosmological Natural Selection  

E-print Network

Smolin (1992) proposed that the fine-tuning problem for parameters of the Standard Model might be accounted for by a Darwinian process of universe reproduction - Cosmological Natural Selection (CNS) - in which black holes give rise to offspring universes with slightly altered parameters. The laws for variation and inheritance of the parameters are also subject to CNS if variation in transmission laws occurs. This is the strategy introduced by Nei (1967) to understand genetic transmission, through the evolutionary theory of modifier genes, whose methodology is adopted here. When mechanisms of variation themselves vary, they are subject to Feldman's (1972) evolutionary Reduction Principle that selection favors greater faithfulness of replication. A theorem of Karlin (1982) allows one to generalize this principle beyond biological genetics to the unknown inheritance laws that would operate in CNS. The reduction principle for CNS is illustrated with a general multitype branching process model of universe creation containing competing inheritance laws. The most faithful inheritance law dominates the ensemble of universes. The Reduction Principle thus provides a mechanism to account for high fidelity of inheritance between universes. Moreover, it reveals that natural selection in the presence of variation in inheritance mechanisms has two distinct objects: maximization of both fitness and faithful inheritance. Tradeoffs between fitness and faithfulness open the possibility that evolved fundamental parameters are compromises, and not local optima to maximize universe production, in which case their local non-optimality may point to their involvement in the universe inheritance mechanisms.

Lee Altenberg

2013-02-20

177

Laboratory and Field Experiments on Expulsion of Selected Ions along Divergent Polar Geomagnetic Fields  

Microsoft Academic Search

Laboratory and Field Experiments on Expulsion of Selected Ions along Divergent Polar Geomagnetic Fields. Laboratory experiments have shown significant gyro-resonance acceleration of minority ion species in a magnetized plasma. Field aligned elctron drifts can provide free energy needed to make this process efficient. The linear magnetized device has a uniform magnetic field linked to two adjustable mirrors at the ends.

A. Y. Wong; B. Deng; B. Quon; R. Wang; J. Hartzell; G. Rosenthal; L. R. Hazelton

2007-01-01

178

Kaon Condensation, Black Holes and Cosmological Natural Selection  

E-print Network

It is argued that a well measured double neutron star binary in which the two neutron stars are more than 4% different from each other in mass or a massive neutron star with mass M > 2 M_sun would put in serious doubt or simply falsify the following chain of predictions: (1) nearly vanishing vector meson mass at chiral restoration, (2) kaon condensation at a density n ~ 3 n_0, (3) the Brown-Bethe maximum neutron star mass M_max ~ 1.5 M_sun and (4) Smolin's `Cosmological Natural Selection' hypothesis.

G. E. Brown; C. -H. Lee; M. Rho

2008-09-04

179

Kaon condensation, black holes, and cosmological natural selection.  

PubMed

It is argued that a well-measured double neutron-star binary in which the two neutron stars are more than 4% different from each other in mass or a massive neutron star with mass M > or approximately 2M(middle dot in circle) would put in serious doubt or simply falsify the following chain of predictions: (1) a nearly vanishing vector meson mass at chiral restoration, (2) kaon condensation at a density n-3n0, (3) the Brown-Bethe maximum neutron-star mass Mmax approximately 1.5M(middle dot in circle), and (4) Smolin's "cosmological natural selection" hypothesis. PMID:18851598

Brown, G E; Lee, Chang-Hwan; Rho, Mannque

2008-08-29

180

Exploring the nature of collisionless shocks under laboratory conditions  

PubMed Central

Collisionless shocks are pervasive in astrophysics and they are critical to understand cosmic ray acceleration. Laboratory experiments with intense lasers are now opening the way to explore and characterise the underlying microphysics, which determine the acceleration process of collisionless shocks. We determine the shock character – electrostatic or electromagnetic – based on the stability of electrostatic shocks to transverse electromagnetic fluctuations as a function of the electron temperature and flow velocity of the plasma components, and we compare the analytical model with particle-in-cell simulations. By making the connection with the laser parameters driving the plasma flows, we demonstrate that shocks with different and distinct underlying microphysics can be explored in the laboratory with state-of-the-art laser systems. PMID:24488212

Stockem, A.; Fiuza, F.; Bret, A.; Fonseca, R. A.; Silva, L. O.

2014-01-01

181

More than Meets the Eye--a Simulation of Natural Selection.  

ERIC Educational Resources Information Center

Presents experiments using wild birds as predators and pastry as prey and colored stones as background to demonstrate natural selection. Describes the exercise as an exercise in simulating natural selection. (Author/CW)

Allen, J. A.; And Others

1987-01-01

182

Cold Spring Harbor Laboratory Press NATURE METHODS | VOL.2 NO.3 | MARCH 2005 | 237 CLASSIC PROTOCOL  

E-print Network

© Cold Spring Harbor Laboratory Press NATURE METHODS | VOL.2 NO.3 | MARCH 2005 | 237 CLASSIC PROTOCOL PUBLISHED IN ASSOCIATION WITH COLD SPRING HARBOR LABORATORY PRESS Fluorescence in situ| Dehydrate slides through an ice-cold ethanol series of 70%, 90% and 100% for 3 min each and then air-dry. 7

Cai, Long

183

Cold Spring Harbor Laboratory Press NATURE METHODS | VOL.2 NO.12 | DECEMBER 2005 | 997 CLASSIC PROTOCOL  

E-print Network

© Cold Spring Harbor Laboratory Press NATURE METHODS | VOL.2 NO.12 | DECEMBER 2005 | 997 CLASSIC PROTOCOL PUBLISHED IN ASSOCIATION WITH COLD SPRING HARBOR LABORATORY PRESS Northern blotting: transfer all air bubbles with a glass rod or pipet. 5| Cut a piece of the appropriate nylon membrane ~1 mm

Cai, Long

184

Emergence and natural selection of drug-resistant prions  

PubMed Central

Drug resistance is a refractory barrier in the battle against many fatal diseases caused by rapidly evolving agents, including HIV, apicomplexans and specific cancers. Emerging evidence suggests that drug resistance might extend to lethal prion disorders and related neurodegenerative amyloidoses. Prions are self-replicating protein conformers, usually ‘cross-?’ amyloid polymers, which are naturally transmitted between individuals and promote phenotypic change. Prion conformers are catalytic templates that specifically convert other copies of the same protein to the prion form. Once in motion, this chain reaction of conformational replication can deplete all non-prion copies of a protein. Typically, prions exist as ensembles of multiple structurally distinct, self-replicating forms or ‘strains’. Each strain confers a distinct phenotype and replicates at different rates depending on the environment. As replicators, prions are units of selection. Thus, natural selection inescapably enriches or depletes various prion strains from populations depending on their conformational fitness (ability to self-replicate) in the prevailing environment. The most successful prions confer advantages to their host as with numerous yeast prions. Here, I review recent evidence that drug-like small molecules can antagonize some prion strains but simultaneously select for drug-resistant prions composed of mammalian PrP or the yeast prion protein, Sup35. For Sup35, the drug-resistant strain configures original intermolecular amyloid contacts that are not ordinarily detected. Importantly, a synergistic small-molecule cocktail counters prion diversity by eliminating multiple Sup35 prion strains. Collectively, these advances illuminate the plasticity of prionogenesis and suggest that synergistic combinatorial therapies might circumvent this pathological vicissitude. PMID:20422111

2010-01-01

185

Contributions of natural and sexual selection to the evolution of premating reproductive isolation: a research agenda.  

PubMed

Speciation by divergent natural selection is well supported. However, the role of sexual selection in speciation is less well understood due to disagreement about whether sexual selection is a mechanism of evolution separate from natural selection, as well as confusion about various models and tests of sexual selection. Here, we outline how sexual selection and natural selection are different mechanisms of evolutionary change, and suggest that this distinction is critical when analyzing the role of sexual selection in speciation. Furthermore, we clarify models of sexual selection with respect to their interaction with ecology and natural selection. In doing so, we outline a research agenda for testing hypotheses about the relative significance of divergent sexual and natural selection in the evolution of reproductive isolation. PMID:24054911

Safran, Rebecca J; Scordato, Elizabeth S C; Symes, Laurel B; Rodríguez, Rafael L; Mendelson, Tamra C

2013-11-01

186

INVESTMENTS IN EDUCATION DEVELOPMENT Deterministic models of natural selection and their  

E-print Network

INVESTMENTS IN EDUCATION DEVELOPMENT Deterministic models of natural selection and their relation and bimatrix games Famous conflicts Replicator equation II Alternative approaches Natural selection and ecology equation II Alternative approaches Natural selection and ecology ­ 3 / 36 #12;Newton law of motion

Pospí�il, Zdenek

187

Evolving Novel Behaviors via Natural Selection A.D. Channon and R.I. Damper  

E-print Network

Evolving Novel Behaviors via Natural Selection A.D. Channon and R.I. Damper Image, Speech novel to their de- signers. Evolutionary emergence via natural selection (without an explicit fitness, the power of natural selection is being demonstrated in prototypal systems such as Tierra (Ray 1991

Fernandez, Thomas

188

New Directions for Studying Selection in Nature: Studies of Performance and Communities  

E-print Network

557 New Directions for Studying Selection in Nature: Studies of Performance and Communities/6/2007 ABSTRACT Natural and sexual selection are crucial factors in the evolu- tionary process, yet recent reviews in a community context via the force of natural selection. For future directions, we argue that researchers

Irschick, Duncan J.

189

Population History and Natural Selection Shape Patterns of Genetic Variation in 132 Genes  

E-print Network

Population History and Natural Selection Shape Patterns of Genetic Variation in 132 Genes Joshua M of natural selection will provide important insights into human evolutionary history and may facilitate the identification of complex disease genes. Although the signature that natural selection imparts on DNA sequence

Sorenson, Michael

190

vol. 151, no. 2 the american naturalist february 1998 A Genetic Polymorphism Maintained by Natural Selection  

E-print Network

that natural selection in these environments can maintain a some autocorrelated variation (Wright 1948; Kimura models of natural selection, the cultures. In particular, Drosophila food that initially has fitness theory of density-dependent natural selection was one of age (Hageman et al. 1990). the first attempts

Ahmad, Sajjad

191

Can natural selection favour altruism between species? G. A. K. WYATT*, S. A. WEST* & A. GARDNER*  

E-print Network

Can natural selection favour altruism between species? G. A. K. WYATT*, S. A. WEST* & A. GARDNER theory of natural selection. However, it has not been formally shown whether between-species altruism can evolve by natural selection, or why this could never happen. Here, we develop a spatial population

West, Stuart

192

The Age-Specific Force of Natural Selection and Walls of Death  

E-print Network

The Age-Specific Force of Natural Selection and Walls of Death Kenneth W. Wachter, Steven N. Evans of natural selection furnishes predictions for senescent mortality due to mutation accumulation, at the price at the intersection of genetics and demography is doubtless W. D. Hamilton's "age-specific force of natural selection

Evans, Steven N.

193

Contrasted Patterns of Selection on MHC-Linked Microsatellites in Natural Populations of the Malagasy  

E-print Network

Contrasted Patterns of Selection on MHC-Linked Microsatellites in Natural Populations of Selection on MHC-Linked Microsatellites in Natural Populations of the Malagasy Plague Reservoir. PLoS ONE 7 Immune genes have been shown to be strongly affected by natural selection [1,2]. In particular, the genes

Paris-Sud XI, Université de

194

Adaptive speciation: the role of natural selection in mechanisms of geographic and  

E-print Network

Adaptive speciation: the role of natural selection in mechanisms of geographic and non the scope of particular speciation mechanisms which assign different roles to natural selection at various; Reproductive isolation; Natural selection; Adaptation; Spandrels 1369-8486/$ - see front matter Ã? 2005 Elsevier

Machery, Edouard

195

Contributions of natural and sexual selection to the evolution of premating  

E-print Network

Contributions of natural and sexual selection to the evolution of premating reproductive isolation 21250, USA Speciation by divergent natural selection is well sup- ported. However, the role of sexual selection in specia- tion is less well understood due to disagreement about whether sexual selection

Rodríguez, Rafael Lucas

196

Effect of Insecticide Resistance on Development, Longevity and Reproduction of Field or Laboratory Selected Aedes aegypti Populations  

PubMed Central

Aedes aegypti dispersion is the major reason for the increase in dengue transmission in South America. In Brazil, control of this mosquito strongly relies on the use of pyrethroids and organophosphates against adults and larvae, respectively. In consequence, many Ae. aegypti field populations are resistant to these compounds. Resistance has a significant adaptive value in the presence of insecticide treatment. However some selected mechanisms can influence important biological processes, leading to a high fitness cost in the absence of insecticide pressure. We investigated the dynamics of insecticide resistance and its potential fitness cost in five field populations and in a lineage selected for deltamethrin resistance in the laboratory, for nine generations. For all populations the life-trait parameters investigated were larval development, sex ratio, adult longevity, relative amount of ingested blood, rate of ovipositing females, size of egglaying and eggs viability. In the five natural populations, the effects on the life-trait parameters were discrete but directly proportional to resistance level. In addition, several viability parameters were strongly affected in the laboratory selected population compared to its unselected control. Our results suggest that mechanisms selected for organophosphate and pyrethroid resistance caused the accumulation of alleles with negative effects on different life-traits and corroborate the hypothesis that insecticide resistance is associated with a high fitness cost. PMID:22431967

Bellinato, Diogo Fernandes; Peixoto, Alexandre Afranio; Valle, Denise; Lima, José Bento Pereira

2012-01-01

197

Selectional restrictions in natural language sentence generation Raymond Kozlowski, Kathleen F. McCoy, and K. VijayShanker  

E-print Network

Selectional restrictions in natural language sentence generation Raymond Kozlowski, Kathleen F. Mc selectional restrictions can be naturally incorporated into our generation architecture and our notion of a lexico­ grammatical resource. Keywords: Natural language generation, Selectional restrictions, Lexical

McCoy, Kathleen F.

198

Genome-Wide Survey of Natural Selection on Functional, Structural, and Network Properties of Polymorphic Sites in  

E-print Network

Genome-Wide Survey of Natural Selection on Functional, Structural, and Network Properties the utility of function-centric approaches for discovering signatures of natural selection. When comparable untenable via conventional interspecific analyses. Key words: evolution, natural selection, yeast, derived

Plotkin, Joshua B.

199

Selectional restrictions in natural language sentence generation Raymond Kozlowski, Kathleen F. McCoy, and K. Vijay-Shanker  

E-print Network

Selectional restrictions in natural language sentence generation Raymond Kozlowski, Kathleen F. Mc selectional restrictions can be naturally incorporated into our generation architecture and our notion of a lexico- grammatical resource. Keywords: Natural language generation, Selectional restrictions, Lexical

McCoy, Kathleen F.

200

Measuring Natural Selection on Proportional Traits: Comparisons of Three Types of Selection Estimates for Resistance and Susceptibility to Herbivore Damage  

Microsoft Academic Search

To compare the strength of natural selection on different traits and in different species, evolutionary biologists typically estimate selection differentials and gradients in standardized units. Measuring selection differentials and gradients in standard deviation units or mean-standardized units facilitates such comparisons by converting estimates with potentially varied units to a common scale. In this note, I compare the performance of variance-

John R. Stinchcombe

2005-01-01

201

MEASUREMENTS OF NATURAL SELECTION ON FLORAL TRAITS IN WILD RADISH (RAPHANUS RAPHANISTRUM). I. SELECTION THROUGH LIFETIME FEMALE FITNESS  

Microsoft Academic Search

Although the role of natural selection in the evolution of floral traits has been of great interest to biologists since Darwin, studies of selection on floral traits through differences in lifetime fitness have been rare. We measured selection acting on flower number, flower size, stigma exsertion, and ovule number per flower using field data on lifetime female fitness (seed production)

JEFFREY K. CONNER; PETER JENNET; E. Healey

202

Rational selection of structurally diverse natural product scaffolds with favorable ADME properties for drug discovery  

Microsoft Academic Search

Natural product analogs are significant sources for therapeutic agents. To capitalize efficiently on the effective features of naturally occurring substances, a natural product-based library production platform has been devised at Aurigene for drug lead discovery. This approach combines the attractive biological and physicochemical properties of natural product scaffolds, provided by eons of natural selection, with the chemical diversity available from

D. S Samiulla; V. V. Vaidyanathan; P. C. Arun; G. Balan; M. Blaze; S Bondre; G. Chandrasekhar; A. Gadakh; R. Kumar; G. Kharvi; H.-O. Kim; S. Kumar; J. A. Malikayil; M. Moger; M. K. Mone; P Nagarjuna; C. Ogbu; D. Pendhalkar; A. V. S. Raja Rao; G. Venkateshwar Rao; V. K. Sarma; S. Shaik; G. V. R. Sharma; S. Singh; C. Sreedhar; R. Sonawane; U. Timmanna; L. W. Hardy

2005-01-01

203

Laboratory Measurements of Seismic Wave Attenuation in Natural Dunite  

NASA Astrophysics Data System (ADS)

In order to examine the processes responsible for the attenuation of seismic shear waves in the Earth's upper mantle, torsional forced-oscillation and microcreep experiements have been conducted on a natural dunite specimen at high temperatures to 1300° C and seismic frequencies from 0.001 to 1Hz. The dunite specimen (from Anita Bay, NZ) consists mainly of olivine (olivine 94%, orthopyroxene 5%, chromite 1%) of about 100 micron average grain size, but some olivine crystals of size up to several millimeters occur randomly. It also contains trace amounts of hydrous phases (loss on ignition is 0.2 wt.%). We measured both untreated and prefired (1200° C, 15hrs) specimens to assess the possible role of water on viscoelasticity. Water weakening of olivine aggregates in creep is currently interpreted in terms of increased concentrations of point defects, resulting in enhanced rates of ionic diffusion and dislocation climb. By analogy, it has been speculated that water significantly affects low-strain viscoelastic behavior as well. Our measurements suggest that shear modulus (G) and dissipation (Q-1) of the prefired specimen are generally larger than those of untreated one. In addition, frequency-dependence of G and Q-1 for the prefired specimen is substantially larger than those of the untreated one. Compared to calculations based on melt-free olivine polycrystals with an average grain size of 100 microns, the measured G and Q-1 are smaller than those calculated. On the other hand, the frequency-dependence of G and Q-1 for the untreated specimen is consistent with those of calculations, although frequency-dependence for the prefired specimen is generally larger relative to the calculations. No distinct dissipation peaks are observed related to the presence of melt, even though the untreated specimen has on the order of 1% melt, and the prefired one also contains a trace amount of melt. Because the measurements were mostly performed at temperatures higher than solidus temperatures, physical properties and distributions of melt may play major roles on interpreting the present experimental results. In the untreated specimen, melt is localized and the dimension of melt pockets is highly heterogeneous. Microstructures and water contents for both specimens will be discussed in detail.

Aizawa, Y.; Barnhoorn, A.; Fitzgerald, J. D.; Faul, U. H.; Jackson, I.

2005-12-01

204

Numerical, Laboratory And Field Studiesof Gas Production FromNatural Hydrate Accumulations in Geologic Media  

SciTech Connect

We discuss the range of activities at Lawrence BerkeleyNational Laboratory in support of gas production from natural hydrates.Investigations of production from the various classes of hydrate depositsby numerical simulation indicate their significant promise as potentialenergy sources. Laboratory studies are coordinated with the numericalstudies and are designed to address knowledge gaps that are important tothe prediction of gas production. Our involvement in field tests is alsobriefly discussed.

Moridis, George J.; Kneafsey, Timothy J.; Kowalsky, Michael; Reagan, Matthew

2006-10-17

205

Learning distinct and complementary feature-selectivities from Natural Colour Videos  

E-print Network

Learning distinct and complementary feature-selectivities from Natural Colour Videos Wolfgang, natural stimuli, temporal coherence Abstract Many biological and artificial neural networks require that are selective to one property of the stimulus while being non-selective to another property. In this way

Körding, Konrad Paul

206

ARTICLE doi:10.1038/nature12160 The importance of mixed selectivity in  

E-print Network

ARTICLE doi:10.1038/nature12160 The importance of mixed selectivity in complex cognitive tasks population activity. This analysis revealed that the observed mixed selectivity can be naturally understood to mixtures of multiple task-related aspects. Such mixed selectivity is highly heterogeneous, seemingly

Wang, Xiao-Jing

207

Statistical Genetics of an Annual Plant, Impatiens capensis. 11. Natural Selection  

Microsoft Academic Search

Measurement of natural selection on correlated characters provides valuable information on fitness surfaces, patterns of directional, stabilizing, or disruptive selection, mechanisms of fitness variation operating in nature, and possible spatial variation in selective pressures. We examined effects of seed weight, germination date, plant size, early growth, and late growth on individual fitness. Path analysis showed that most characters had direct

Thomas Mitchell-Olds; Joy Bergelson

208

NATURAL SELECTION ON PROTEIN POLYMORPHISM IN THE RODENT GENUS PEROMYSCUS: EVIDENCE FROM INTERLOCUS CONTRASTS  

Microsoft Academic Search

The effects of natural selection are generally locus-specific, whereas migration, drift, and inbreeding are expected to have relatively uniform effects across the entire genome. This suggests that multilocus surveys of multiple populations can be used to distinguish selection from demographic effects. The purpose of this study was to test for evidence of selection on protein polymorphism in natural populations of

Jay F. Storz; Michael W. Nachman

2003-01-01

209

Six Classroom Exercises to Teach Natural Selection to Undergraduate Biology Students  

ERIC Educational Resources Information Center

Students in introductory biology courses frequently have misconceptions regarding natural selection. In this paper, we describe six activities that biology instructors can use to teach undergraduate students in introductory biology courses how natural selection causes evolution. These activities begin with a lesson introducing students to natural

Kalinowski, Steven T.; Leonard, Mary J.; Andrews, Tessa M.; Litt, Andrea R.

2013-01-01

210

An Evaluation of Strategies for Selective Utterance Verification for Spoken Natural Language Dialog  

E-print Network

An Evaluation of Strategies for Selective Utterance Verification for Spoken Natural Language Dialog Selective Verification of Questionable User Inputs Every system that uses natural language under­ standing­ ferent users, 141 problem­solving dialogs, and 2840 user utterances, the Circuit Fix­It Shop natural

Smith, Ronnie W.

211

Safety in the Chemical Laboratory: Selecting Chemical Protective Gloves Properly in the Lab.  

ERIC Educational Resources Information Center

Discusses the selection of gloves for the chemistry laboratory. Provides checklists for the purposes of the gloves, and the factors including permeation rate, breakthrough time, friction, and cost. Lists eight rules for preventing skin exposure and minimizing area contamination. Lists six references. (YP)

Hart, Charles

1989-01-01

212

Selection of Pupation Habitats by Oriental Fruit Fly Larvae in the Laboratory  

Microsoft Academic Search

We performed a series of laboratory experiments to determine the effects of shade, soil moisture, and soil compaction on the selection of pupation habitats by wandering late-instar Oriental fruit flies, Bactrocera dorsalis (Hendel). Larvae showed a strong preference toward pupating in shaded rather than brightly lit areas, in moist rather than dry soil, and in soil with larger particle sizes.

Andrei V. Alyokhin; Christian Mille; Russell H. Messing; Jian J. Duan

2001-01-01

213

Natural selection on floral traits of Lobelia (Lobeliaceae): spatial and temporal variation.  

PubMed

The strength and direction of natural selection on floral traits can vary spatially and temporally because of variation in the biotic and abiotic environment. High spatial variation in selection should lead to differentiation of floral traits among populations. In contrast, high temporal variation in selection should retard the evolution of population-specific floral phenotypes. To determine the relative importance of spatial vs. temporal variation in natural selection, we measured phenotypic selection on seven floral traits of the wildflowers Lobelia cardinalis and L. siphilitica in 1999 and 2000. Lobelia cardinalis experienced significant temporal variation in selection, whereas L. siphilitica experienced spatial variation in selection on the same traits. This variation in selection on floral traits was associated with spatial and temporal differences in the soil microenvironment. Although few studies of natural selection include spatial or temporal replicates, our results suggest that such replication is critical for understanding the distribution of phenotypes in nature. PMID:21659233

Caruso, Christina M; Peterson, S Brook; Ridley, Caroline E

2003-09-01

214

Maintenance of an aminopeptidase allele frequency cline by natural selection.  

PubMed

The product of the Lap locus in the marine bivalve Mytilus edulis is a neutral, membrane-associated aminopeptidase that is primarily localized on intestinal microvilli and in digestive cell lysosomes. Natural populations are genetically differentiated at the Lap locus between areas of differing salinity. A steep (0.55-0.15) allele frequency cline connects differentiated populations between the Atlantic Ocean and Long Island Sound. We demonstrate an annual gene flow/mortality cycle in cline populations whereby gene frequencies after mortality are correlated with salinity and enzyme activity. The cline is spatially and temporally unstable in immigrants, but stable in residents after mortality. Mortality is nonrandom with regard to the Lap locus; genotype-dependent properties of the aminopeptidase enzyme apparently led to a differential rate of the utilizaiton of nutrient reserves because selected genotypes exhibited an increased rate of tissue weight loss. Aminopeptidase genotypes are differentially adapted to different temperatures and salinities, which provides a mechanism for the relationship among biochemical, physiological, and population phenotypes. PMID:6933563

Koehn, R K; Newell, R I; Immermann, F

1980-09-01

215

Reference site selection report for the advanced liquid metal reactor at the Idaho National Engineering Laboratory  

SciTech Connect

This Reference Site Selection Report was prepared by EG G, Idaho Inc., for General Electric (GE) to provide information for use by the Department of Energy (DOE) in selecting a Safety Test Site for an Advanced Liquid Metal Reactor. Similar Evaluation studies are planned to be conducted at other potential DOE sites. The Power Reactor Innovative Small Module (PRISM) Concept was developed for ALMR by GE. A ALMR Safety Test is planned to be performed on a DOE site to demonstrate features and meet Nuclear Regulatory Commission Requirements. This study considered possible locations at the Idaho National Engineering Laboratory that met the ALMR Prototype Site Selection Methodology and Criteria. Four sites were identified, after further evaluation one site was eliminated. Each of the remaining three sites satisfied the criteria and was graded. The results were relatively close. Thus concluding that the Idaho National Engineering Laboratory is a suitable location for an Advanced Liquid Metal Reactor Safety Test. 23 refs., 13 figs., 9 tabs.

Sivill, R.L.

1990-03-01

216

Natural selection at linked sites in humans Bret A. Payseur*, Michael W. Nachman  

E-print Network

Natural selection at linked sites in humans Bret A. Payseur*, Michael W. Nachman Department and empirical work indicates that patterns of neutral polymorphism can be affected by linked, selected mutations. Under background selection, deleterious mutations removed from a population by purifying selection cause

Nachman, Michael

217

Artificial selection for structural color on butterfly wings and comparison with natural evolution.  

PubMed

Brilliant animal colors often are produced from light interacting with intricate nano-morphologies present in biological materials such as butterfly wing scales. Surveys across widely divergent butterfly species have identified multiple mechanisms of structural color production; however, little is known about how these colors evolved. Here, we examine how closely related species and populations of Bicyclus butterflies have evolved violet structural color from brown-pigmented ancestors with UV structural color. We used artificial selection on a laboratory model butterfly, B. anynana, to evolve violet scales from UV brown scales and compared the mechanism of violet color production with that of two other Bicyclus species, Bicyclus sambulos and Bicyclus medontias, which have evolved violet/blue scales independently via natural selection. The UV reflectance peak of B. anynana brown scales shifted to violet over six generations of artificial selection (i.e., in less than 1 y) as the result of an increase in the thickness of the lower lamina in ground scales. Similar scale structures and the same mechanism for producing violet/blue structural colors were found in the other Bicyclus species. This work shows that populations harbor large amounts of standing genetic variation that can lead to rapid evolution of scales' structural color via slight modifications to the scales' physical dimensions. PMID:25092295

Wasik, Bethany R; Liew, Seng Fatt; Lilien, David A; Dinwiddie, April J; Noh, Heeso; Cao, Hui; Monteiro, Antónia

2014-08-19

218

SELECTED ASPECTS OF THE NATURAL HISTORY AND CULTURE OF GILA CHUB Andrew Alan Schultz  

E-print Network

SELECTED ASPECTS OF THE NATURAL HISTORY AND CULTURE OF GILA CHUB by Andrew Alan Schultz of Philosophy. ___________________________________________ ________________ Scott A. Bonar Date requirement. ___________________________________________ _________________ Dissertation Director: Scott Bonar

Bonar, Scott A.

219

Sexual dichromatism in frogs: natural selection, sexual selection and unexpected diversity  

PubMed Central

Sexual dichromatism, a form of sexual dimorphism in which males and females differ in colour, is widespread in animals but has been predominantly studied in birds, fishes and butterflies. Moreover, although there are several proposed evolutionary mechanisms for sexual dichromatism in vertebrates, few studies have examined this phenomenon outside the context of sexual selection. Here, we describe unexpectedly high diversity of sexual dichromatism in frogs and create a comparative framework to guide future analyses of the evolution of these sexual colour differences. We review what is known about evolution of colour dimorphism in frogs, highlight alternative mechanisms that may contribute to the evolution of sexual colour differences, and compare them to mechanisms active in other major groups of vertebrates. In frogs, sexual dichromatism can be dynamic (temporary colour change in males) or ontogenetic (permanent colour change in males or females). The degree and the duration of sexual colour differences vary greatly across lineages, and we do not detect phylogenetic signal in the distribution of this trait, therefore frogs provide an opportunity to investigate the roles of natural and sexual selection across multiple independent derivations of sexual dichromatism. PMID:22993253

Bell, Rayna C.; Zamudio, Kelly R.

2012-01-01

220

Sexual dichromatism in frogs: natural selection, sexual selection and unexpected diversity.  

PubMed

Sexual dichromatism, a form of sexual dimorphism in which males and females differ in colour, is widespread in animals but has been predominantly studied in birds, fishes and butterflies. Moreover, although there are several proposed evolutionary mechanisms for sexual dichromatism in vertebrates, few studies have examined this phenomenon outside the context of sexual selection. Here, we describe unexpectedly high diversity of sexual dichromatism in frogs and create a comparative framework to guide future analyses of the evolution of these sexual colour differences. We review what is known about evolution of colour dimorphism in frogs, highlight alternative mechanisms that may contribute to the evolution of sexual colour differences, and compare them to mechanisms active in other major groups of vertebrates. In frogs, sexual dichromatism can be dynamic (temporary colour change in males) or ontogenetic (permanent colour change in males or females). The degree and the duration of sexual colour differences vary greatly across lineages, and we do not detect phylogenetic signal in the distribution of this trait, therefore frogs provide an opportunity to investigate the roles of natural and sexual selection across multiple independent derivations of sexual dichromatism. PMID:22993253

Bell, Rayna C; Zamudio, Kelly R

2012-12-01

221

Field and laboratory measurements of bivalve filtration of natural marine bacterioplankton  

Microsoft Academic Search

Ahstruct Clearance of natural bacterioplankton and phytoplankton by Mytihs edulis, Geukensia demissa, and Myu arenuriu was measured in the laboratory. Of the three, only Geukensia proved capable of efficient clearance of bacteria. Field measurements of clearance across a 46-m-wide Myths bed showed substantial removal of phytoplankton but no effect on bnc- terial concentrations. Measurements of the living gill tissue of

RICHARD T. WRIGHT; RICHARD B. COFFIN; CURTIS P. ERSING; DANIEL PEARSON

1982-01-01

222

Blindisms: Treatment by Punishment and Reward in Laboratory and Natural Settings.  

ERIC Educational Resources Information Center

Separate experiments were done with six blind students (ages 16-20 years) to test the effectiveness of using punishment (prerecorded sound of chalk screeching on a blackboard) and positive reinforcement (money) in natural and laboratory settings to reduce "blindisms" (stereotypic behaviors). (Author/DLS)

Blasch, Bruce B.

1978-01-01

223

High School Chemistry Students' Scientific Epistemologies and Perceptions of the Nature of Laboratory Inquiry  

ERIC Educational Resources Information Center

This quantitative study investigated the relationship between Chemistry students' scientific epistemologies and their perceptions of the nature of laboratory inquiry. Seventy-two Advanced Level Chemistry students were surveyed. The students were sampled from twelve schools in three of Zimbabwe's nine administrative provinces. Students' scientific…

Vhurumuku, Elaosi

2011-01-01

224

Molluscan Natural Products as Biological Models: Chemical Ecology, Histology and Laboratory Culture  

Microsoft Academic Search

known for centuries. However, only recently have modern technologies and advances in the fields of chemistry, chemical ecology, anatomy, histology, and laboratory culture allowed the exploitation of new, unprecedented applications of natural products. Recent studies have dealt with (a) the role that these compounds have in the sea in protecting the animals (e.g., chemical defense), or in mediating their intraspecific

Conxita Avila

225

Assessment of natural selection in a hybrid population of mussels: evaluation of exogenous vs endogenous selection models  

Microsoft Academic Search

We examined natural selection within a population of marine mussels, sampled in southwestern England in June 1991, containing\\u000a a high frequency of hybrids between Mytilus edulis L. and M. galloprovincialis Lmk. This system is particularly tractable for the assessment of natural selection because hybridization is common and individual\\u000a mussels can be aged, allowing changes in the frequency of hybrid genotypes

R. Wilhelm; T. J. Hilbish

1998-01-01

226

Copyright 2003 by the Genetics Society of America Heterogeneous Selection at Specific Loci in Natural Environments in  

E-print Network

in the face of purifying natural selection. One possible explanation for this observed variation is the action of heterogeneous natural selection in the wild. Here we report that selection on quantitative trait loci (QTL exposed to selection in different natural environments. Selection on allelic variation also depended upon

Purugganan, Michael D.

227

Amdinocillin (Mecillinam) Resistance Mutations in Clinical Isolates and Laboratory-Selected Mutants of Escherichia coli.  

PubMed

Amdinocillin (mecillinam) is a ?-lactam antibiotic that is used mainly for the treatment of uncomplicated urinary tract infections. The objectives of this study were to identify mutations that confer amdinocillin resistance on laboratory-isolated mutants and clinical isolates of Escherichia coli and to determine why amdinocillin resistance remains rare clinically even though resistance is easily selected in the laboratory. Under laboratory selection, frequencies of mutation to amdinocillin resistance varied from 8 × 10(-8) to 2 × 10(-5) per cell, depending on the concentration of amdinocillin used during selection. Several genes have been demonstrated to give amdinocillin resistance, but here eight novel genes previously unknown to be involved in amdinocillin resistance were identified. These genes encode functions involved in the respiratory chain, the ribosome, cysteine biosynthesis, tRNA synthesis, and pyrophosphate metabolism. The clinical isolates exhibited significantly greater fitness than the laboratory-isolated mutants and a different mutation spectrum. The cysB gene was mutated (inactivated) in all of the clinical isolates, in contrast to the laboratory-isolated mutants, where mainly other types of more costly mutations were found. Our results suggest that the frequency of mutation to amdinocillin resistance is high because of the large mutational target (at least 38 genes). However, the majority of these resistant mutants have a low growth rate, reducing the probability that they are stably maintained in the bladder. Inactivation of the cysB gene and a resulting loss of cysteine biosynthesis are the major mechanism of amdinocillin resistance in clinical isolates of E. coli. PMID:25583718

Thulin, Elisabeth; Sundqvist, Martin; Andersson, Dan I

2015-03-01

228

Polycyclic aromatic hydrocarbons at selected burning grounds at Los Alamos National Laboratory  

SciTech Connect

A commercial immunoassay field test (IFT) was used to rapidly assess the total concentrations of polycyclic aromatic hydrocarbons (PAHs) in the soil at selected burning grounds within the explosives corridor at Los Alamos National Laboratory (LANL). Results were compared with analyses obtained from LANL Analytical Laboratory and from a commercial laboratory. Both used the Environmental Protection Agency`s (EPA`s) Methods 8270 and 8310. EPA`s Method 8270 employs gas chromatography and mass spectral analyses, whereas EPA`s Method 8310 uses an ultraviolet detector in a high-performance liquid chromatography procedure. One crude oil sample and one diesel fuel sample, analyzed by EPA Method 8270, were included for references. On an average the IFT results were lower for standard samples and lower than the analytical laboratory results for the unknown samples. Sites were selected to determine whether the PAHs came from the material burned or the fuel used to ignite the burn, or whether they are produced by a high-temperature chemical reaction during the burn. Even though the crude oil and diesel fuel samples did contain measurable quantities of PAHs, there were no significant concentrations of PAHs detected in the ashes and soil at the burning grounds. Tests were made on fresh soil and ashes collected after a large burn and on aged soil and ashes known to have been at the site more than three years. Also analyzed were twelve-year-old samples from an inactive open burn cage.

Harris, B.W.; Minor, L.K.M.; Flucas, B.J.

1998-02-01

229

Widespread Genomic Signatures of Natural Selection in Hominid Evolution  

PubMed Central

Selection acting on genomic functional elements can be detected by its indirect effects on population diversity at linked neutral sites. To illuminate the selective forces that shaped hominid evolution, we analyzed the genomic distributions of human polymorphisms and sequence differences among five primate species relative to the locations of conserved sequence features. Neutral sequence diversity in human and ancestral hominid populations is substantially reduced near such features, resulting in a surprisingly large genome average diversity reduction due to selection of 19–26% on the autosomes and 12–40% on the X chromosome. The overall trends are broadly consistent with “background selection” or hitchhiking in ancestral populations acting to remove deleterious variants. Average selection is much stronger on exonic (both protein-coding and untranslated) conserved features than non-exonic features. Long term selection, rather than complex speciation scenarios, explains the large intragenomic variation in human/chimpanzee divergence. Our analyses reveal a dominant role for selection in shaping genomic diversity and divergence patterns, clarify hominid evolution, and provide a baseline for investigating specific selective events. PMID:19424416

McVicker, Graham; Gordon, David; Davis, Colleen; Green, Phil

2009-01-01

230

Hidden Evolution: Progress and Limitations in Detecting Multifarious Natural Selection  

Microsoft Academic Search

From illustrative examples of research on the best-studied group of species to date, Drosophila melanogaster and its closest relatives, we argue that selection is multifarious, but often hidden. Selective fixation of new, highly advantageous alleles is the most parsimonious explanation for a typical pattern of molecular variation observed in genomic regions characterized by very low recombination: drastically reduced DNA sequence

Norman A. Johnson; Richard M. Kliman

2002-01-01

231

Visions of Evolution: Self-organization proposes what natural selection disposes David Batten1*  

E-print Network

." Charles Darwin SUMMARY This paper reviews the seven "visions" of evolution proposed by Depew and Weber1 Visions of Evolution: Self-organization proposes what natural selection disposes David Batten1 drives evolution; (2) self-organization drives evolution, or (3) natural selection and self

Boschetti, Fabio

232

Visions of Evolution: Self-organization Proposes What Natural Selection Disposes  

Microsoft Academic Search

This article reviews the seven visions of evolution proposed by Depew and Weber (1995, Darwinism Evolving: Systems Dynamics and the Genealogy of Natural Selection, Cambridge, MA: MIT Press), concluding that each posited relationship between natural selection and self-organization has suited different aims and approaches. In the second section of the article, we show that these seven viewpoints may be collapsed

David Batten; Fabio Boschetti

2008-01-01

233

Genetic Programming as a Means for Programming Computers by Natural Selection  

E-print Network

Genetic Programming as a Means for Programming Computers by Natural Selection JOHN R. KOZA Computer of time as the consequence of Darwinian natural selection and the creative effects of sexual recombination in the middle of an irregular room and move the box to the wall. Hierarchical automatic function definition

Fernandez, Thomas

234

Natural selection influences AFLP intraspecific genetic variability and introgression patterns in Atlantic eels  

Microsoft Academic Search

Investigating patterns of genetic variation in hybridizing species provides an opportunity to understand the impact of natural selection on intraspecific genetic variability and inter- specific gene exchange. The Atlantic eels Anguilla rostrata and A. anguilla each occupy a large heterogeneous habitat upon which natural selection could differentially shape genetic variation. They also produce viable hybrids only found in Iceland. However,

2009-01-01

235

Natural selection drives clinal life history patterns in the perennial sunflower species, Helianthus maximiliani  

E-print Network

Natural selection drives clinal life history patterns in the perennial sunflower species but also may result from nonselective processes, such as genetic drift, population bottlenecks & Agren 2002; Storz 2002; Hall et al. 2007). Natural selection represents a plausible driver of clinal

Nippert, Jesse

236

Adaptive walks on behavioural landscapes and the evolution of optimal behaviour by natural selection  

Microsoft Academic Search

Summary  One of the main challenges to the adaptationist programme in general and to the use of optimality models in behavioural and evolutionary ecology in particular is that natural selection need not optimise fitness. This challenge is addressed by considering the evolution of optimal patch choice by natural selection. The behavioural model is based on a state variable approach in which

Marc Mangel

1991-01-01

237

Natural selection, rational economic behavior, and alternative outcomes of the evolutionary process  

Microsoft Academic Search

The implicit assumption that an economic natural selection process will lead to rational behavior has been key to much of modern economic theory. However, when the process of natural selection as it would apply to economic markets is thought through, it does not necessarily lead to rational behavior, nor to behavior that appears “as if” it is rational. It is

Joshua Frank

2003-01-01

238

Adding Dynamical Sufficiency to Fisher’s Fundamental Theorem of Natural Selection  

Microsoft Academic Search

Fisher’s “fundamental theorem of natural selection” is famously robust and versatile but, frustratingly, it is dynamically insufficient: it can only predict how fitness will evolve over the course of a single generation. Consequently, his theorem has not been used for predicting the course of evolution but instead for detecting natural selection. His theorem employs only one facet of the fitness

Philip J. Gerrish; Paul D. Sniegowski

2011-01-01

239

Thermodynamic Cycle Selection for Distributed Natural Gas Liquefaction  

Microsoft Academic Search

Natural gas liquefaction plants with cooling capacities of approximately 100 kW are facilitating the development of a distributed LNG infrastructure. To be economically viable, liquefiers of this scale must be able to operate on a variety of feed gases while offering relatively low capital costs, short delivery time, and good performance. This paper opens with a discussion of a natural

M. A. Barclay; D. F. Gongaware; K. Dalton; M. P. Skrzypkowski

2004-01-01

240

Natural Selection and Genetic Drift: Their Probabilistic Characterization  

Microsoft Academic Search

The modern theory of heredity is deeply based on the fact that genetic information transmitted from generation to generation supervenes on the chemical material, called DNA sequences. The evolutionary nature of genetic transmission has been studied through the population genetic models, originated by Mendel, and the collection of these models is the theory of population genetics. In these models, natural

Yosaku Nishiwaki

241

The Slumgullion Natural Laboratory: Landsliding Mechanisms Inferred from Seismic and Geodetic Observations  

NASA Astrophysics Data System (ADS)

Effective mitigation of landslide hazards requires accurate characterization of landslide subsurface geometry and failure mode, both of which are difficult to obtain. To evaluate a new geophysical approach for landslide and faulting characterization in a natural setting, we recently deployed an array of 88 single-channel seismometers complemented by geodetic measurements made using GPS and a robotic total-station theodolite at the 3.9-km-long Slumgullion landslide in southwestern Colorado. This landslide was selected because of its size, nearly continuous movement, and the documentation of its failure modes from previous continuous monitoring and laboratory testing. Our previous studies identified that the landslide material (soil and weathered rock) dilates during shear and has very low permeability. These characteristics result in generation of excess negative pore-water pressures along shear surfaces that restrain movement by increasing effective normal stresses. We’ve also observed that lateral shear boundaries episodically relocate, forming new shear surfaces. Although we have only just completed the data-gathering phase, we’ve identified that landslide movement varies considerably, sometimes occurring aseismically and other times producing seismic tremor and localized slidequakes. Our working hypothesis is that steady aseismic slip occurs where shear-zone porosity is at critical state, tremor radiates from areas where increased effective stress from shear-zone dilation sporadically resists movement, and slidequakes are produced from similarly dilating areas, especially where and when new shear surfaces are formed. Complex rearrangements between individual kinematic units comprising the landslide may also affect its mode of failure and slip and consequent observables. Further analyses of geodetic, seismic, and environmental data will refine our hypotheses. Location estimates of the large number of observed seismic events may constrain the geometry of the landslide’s basal shear zone. Conventional geophysical techniques such as seismic refraction have proven ineffective for imaging the base of the Slumgullion and other landslides because landslide materials do not adequately differ from underlying materials. Our findings should help understand landslides in general, as well as other phenomena that involve naturally occurring shear failure of soil and rock, such as earthquakes, glacier movement, and volcanic eruptions.

Schulz, W. H.; Kean, J. W.; Gomberg, J. S.; Bodin, P.; Wang, G.; Coe, J. A.; MacQueen, P.; Foster, K.; Creager, K.

2009-12-01

242

Laboratory divergence of Methylobacterium extorquens AM1 through unintended domestication and past selection for antibiotic resistance  

PubMed Central

Background A common assumption of microorganisms is that laboratory stocks will remain genetically and phenotypically constant over time, and across laboratories. It is becoming increasingly clear, however, that mutations can ruin strain integrity and drive the divergence or “domestication” of stocks. Since its discovery in 1960, a stock of Methylobacterium extorquens AM1 (“AM1”) has remained in the lab, propagated across numerous growth and storage conditions, researchers, and facilities. To explore the extent to which this lineage has diverged, we compared our own “Modern” stock of AM1 to a sample archived at a culture stock center shortly after the strain’s discovery. Stored as a lyophilized sample, we hypothesized that this Archival strain would better reflect the first-ever isolate of AM1 and reveal ways in which our Modern stock has changed through laboratory domestication or other means. Results Using whole-genome re-sequencing, we identified some 29 mutations – including single nucleotide polymorphisms, small indels, the insertion of mobile elements, and the loss of roughly 36 kb of DNA - that arose in the laboratory-maintained Modern lineage. Contrary to our expectations, Modern was both slower and less fit than Archival across a variety of growth substrates, and showed no improvement during long-term growth and storage. Modern did, however, outperform Archival during growth on nutrient broth, and in resistance to rifamycin, which was selected for by researchers in the 1980s. Recapitulating selection for rifamycin resistance in replicate Archival populations showed that mutations to RNA polymerase B (rpoB) substantially decrease growth in the absence of antibiotic, offering an explanation for slower growth in Modern stocks. Given the large number of genomic changes arising from domestication (28), it is somewhat surprising that the single other mutation attributed to purposeful laboratory selection accounts for much of the phenotypic divergence between strains. Conclusions These results highlight the surprising degree to which AM1 has diverged through a combination of unintended laboratory domestication and purposeful selection for rifamycin resistance. Instances of strain divergence are important, not only to ensure consistency of experimental results, but also to explore how microbes in the lab diverge from one another and from their wild counterparts. PMID:24384040

2014-01-01

243

Assessment of Application Technology of Natural User Interfaces in the Creation of a Virtual Chemical Laboratory  

NASA Astrophysics Data System (ADS)

Natural User Interfaces (NUI) are now widely used in electronic devices such as smartphones, tablets and gaming consoles. We have tried to apply this technology in the teaching of chemistry in middle school and high school. A virtual chemical laboratory was developed in which students can simulate the performance of laboratory activities similar to those that they perform in a real laboratory. Kinect sensor was used for the detection and analysis of the student's hand movements, which is an example of NUI. The studies conducted found the effectiveness of educational virtual laboratory. The extent to which the use of a teaching aid increased the students' progress in learning chemistry was examined. The results indicate that the use of NUI creates opportunities to both enhance and improve the quality of the chemistry education. Working in a virtual laboratory using the Kinect interface results in greater emotional involvement and an increased sense of self-efficacy in the laboratory work among students. As a consequence, students are getting higher marks and are more interested in the subject of chemistry.

Jagodzi?ski, Piotr; Wolski, Robert

2014-09-01

244

Assessment of Application Technology of Natural User Interfaces in the Creation of a Virtual Chemical Laboratory  

NASA Astrophysics Data System (ADS)

Natural User Interfaces (NUI) are now widely used in electronic devices such as smartphones, tablets and gaming consoles. We have tried to apply this technology in the teaching of chemistry in middle school and high school. A virtual chemical laboratory was developed in which students can simulate the performance of laboratory activities similar to those that they perform in a real laboratory. Kinect sensor was used for the detection and analysis of the student's hand movements, which is an example of NUI. The studies conducted found the effectiveness of educational virtual laboratory. The extent to which the use of a teaching aid increased the students' progress in learning chemistry was examined. The results indicate that the use of NUI creates opportunities to both enhance and improve the quality of the chemistry education. Working in a virtual laboratory using the Kinect interface results in greater emotional involvement and an increased sense of self-efficacy in the laboratory work among students. As a consequence, students are getting higher marks and are more interested in the subject of chemistry.

Jagodzi?ski, Piotr; Wolski, Robert

2015-02-01

245

Dynamics of extinction and the selection of nature reserves.  

PubMed Central

Familiar quantitative reserve-selection techniques are tailored to simple decision problems, where the representation of species is sought at minimum cost. However, conservationists have begun to ask whether representing species in reserve networks is sufficient to avoid local extinctions within selected areas. An attractive, but previously untested idea is to model current species' probabilities of occurrence as an estimate of local persistence in the near future. Using distribution data for passerine birds in Great Britain, we show that (i) species' probabilities of occurrence are negatively related to local probabilities of extinction, at least when a particular 20-year period is considered, and (ii) local extinctions can be reduced if areas are selected to maximize current species' probabilities of occurrence We suggest that more extinctions could be avoided if even a simple treatment of persistence were to be incorporated within reserve selection methods. PMID:12396495

Araújo, Miguel B; Williams, Paul H; Fuller, Robert J

2002-01-01

246

Designing an Auction Protocol under Asymmetric Information on Nature's Selection  

E-print Network

, Tatsunokuchi-machi, Nomi-gun, Ishikawa 923-1292, JAPAN itota@jaist.ac.jp Makoto Yokoo, and Shigeo Matsubara NTT Communication Science Laboratories NTT Corporation 2 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0237, JAPAN. First, agent-mediated electronic marketplaces [2] (e.g., eMediator[9], AuctionBot[10], and GroupBuy

Ito, Takayuki

247

Natural selection and rational decision: two concepts of optimization  

Microsoft Academic Search

There are two different kinds of optimization: “selection” and “rationality” optimization. Selection optimization characterizes\\u000a competition in human and nonhuman societies sharing the same market or niche. “Rationality optimization”, on the other hand,\\u000a characterizes human and nonhuman decision making processes. The two kinds of optimization generate the same result: agents\\u000a end up behaving efficiently. Nonetheless, we should not downplay the differences

Elias L. Khalil

2009-01-01

248

The natural history of hypotheses about the selection task: towards a philosophy of science  

E-print Network

The natural history of hypotheses about the selection task: towards a philosophy of science, K. & Chung, M. (eds.) Psychology of rea- soning. Psychology Press. Abstract Wason's (1968) selection's account of science and Wason's account of the ab- stract selection task have lived full lives

van Lambalgen, Michiel

249

Abstract Sexual isolation can evolve due to natural selection against hybrids (reinforcement). However,  

E-print Network

Abstract Sexual isolation can evolve due to natural selection against hybrids (reinforcement, can contribute to the evolution of sexual isolation. Here we review how different selective processes describe selective pro- cesses which can promote the evolution of sexual iso- lation, present methods

Crespi, Bernard J.

250

LETTER doi:10.1038/nature10971 Sexual selection enables long-term coexistence  

E-print Network

LETTER doi:10.1038/nature10971 Sexual selection enables long-term coexistence despite ecological of sexual selection to include two ubiquitous features ofpopulationswithsexualselection­4 . It therefore seems that sexual selection is an important mechanism for maintaining coexist- ence. Indeed

Dieckmann, Ulf

251

Comparing artificial and natural selection in rate of adaptation to genetic stress in Aspergillus nidulans  

Microsoft Academic Search

In an experimental study of adaptation to negative pleiotropic effects of a major fungicide resistance mutation in the filamentous fungus Aspergillus nidulans we have investigated the relative effectiveness of artificial selection vs. natural selection on the rate of compensatory evolution. Using mycelial growth rate as a fitness measure, artificial selection involved the weekly transfer of the fastest growing sector onto

S. E. Schoustra; S. M. Slakhorst-Wandel; A. J. M. Debets; R. F. Hoekstra

2005-01-01

252

NATURAL SELECTION ON FLORAL TRAITS OF LOBELIA (LOBELIACEAE): SPATIAL AND TEMPORAL VARIATION1  

Microsoft Academic Search

The strength and direction of natural selection on floral traits can vary spatially and temporally because of variation in the biotic and abiotic environment. High spatial variation in selection should lead to differentiation of floral traits among populations. In contrast, high temporal variation in selection should retard the evolution of population-specific floral phenotypes. To determine the relative importance of spatial

CHRISTINA M. CARUSO; S. BROOK PETERSON; CAROLINE E. RIDLEY

253

LIFETIME SELECTION ON HERITABLE LIFE-HISTORY TRAITS IN A NATURAL POPULATION OF RED SQUIRRELS  

Microsoft Academic Search

Despite their importance in evolutionary biology, heritability and the strength of natural selection have rarely been estimated in wild populations of iteroparous species or have usually been limited to one particular event during an organism's lifetime. Using an animal-model restricted maximum likelihood and phenotypic selection models, we estimated quantitative genetic parameters and the strength of lifetime selection on parturition date

D. Réale; D. Berteaux; A. G. McAdam; S. Boutin

2003-01-01

254

Natural or Internal Selection? The Case of Canalization in Complex Evolutionary Systems  

Microsoft Academic Search

Using biological examples and theoretical arguments, the case is presented for extending the notion of natural selection to include internal selection in order to account for the evolution of complex systems. It is suggested that we take into consideration internal factors that arise from the hierarchical dynamics of complex systems. In addition to environmental selection, it is argued, decisive constraints

Alexander Riegler

2008-01-01

255

Caprylate-thallous agar medium for selectively isolating Serratia and its utility in the clinical laboratory.  

PubMed Central

A defined agar medium (hereinafter designated caprylate-thallous [CT5 agar) containing 0.01% yeast extract, 0.1% caprylic (n-octanoic) acid, and 0.025% thallous sulfate is highly selective for all Serratia species and effectively discriminates against most non-Serratia strains likely to be in the same habitats. The selectivity of CT agar is demonstrated by the very high efficiency of colony formation (mean, 80.7% of that on a nonselective complex medium) on CT agar by known Serratia strains and the very low efficiency of colony formation (close to zero) on CT agar by bacterial strains known not to be Serratia. The utility of this medium in actual clinical laboratory practice is demonstrated by the more rapid and higher recovery of Serratia on this selective medium as compared to conventional procedures of in-tandem runs of 513 consecutive urine, feces, and sputum specimens. Pigmented and nonpigmented Serratia strains deliberately added to fecal specimens can be selectively and quantitatively recovered on CT agar. CT agar compares favorably with, or in some cases is an improvement over, other selective media which have been recommended for isolating Serratia. This selective CT agar medium could be quite useful in ecological surveys, especially those related to hospital-acquired infections. PMID:972193

Starr, M P; Grimont, P A; Grimont, F; Starr, P B

1976-01-01

256

Feature Selection of Facial Displays for Detection of Non Verbal Communication in Natural Conversation  

E-print Network

Feature Selection of Facial Displays for Detection of Non Verbal Communication in Natural to address these challenges by initially creating a data set of natural conversation which is then annotated by multiple observers. The participants are Figure 1. Example frames from natural conversation video se

Bowden, Richard

257

Mini-conference on Angular Momentum Transport in Laboratory and Nature  

SciTech Connect

This paper provides a concise summary of the current status of the research and future perspectives discussed in the Mini-Conference on Angular Momentum Transport in Laboratory and Nature. This Mini-conference, sponsored by the Topical Group on Plasma Astrophysics, was held as part of the American Physical Society's Division of Plasma Physics 2007 Annual Meeting (November 12{16, 2007). This Mini-conference covers a wide range of phenomena happening in fluids and plasmas, either in laboratory or in nature. The purpose of this paper is not to comprehensively review these phenomena, but to provide a starting point for interested readers to refer to related research in areas other than their own.

Hantao Ji, Philipp Kronberg, Stewart C. Prager, and Dmitri A. Uzdensky

2008-05-06

258

Mini-conference on angular momentum transport in laboratory and nature  

NASA Astrophysics Data System (ADS)

This paper provides a concise summary of the current status of the research and future perspectives discussed in the Mini-Conference on Angular Momentum Transport in Laboratory and Nature. This mini-conference, sponsored by the Topical Group on Plasma Astrophysics, was held as part of the American Physical Society's Division of Plasma Physics 2007 Annual Meeting (November 12-16, 2007). This mini-conference covers a wide range of phenomena happening in fluids and plasmas, either in laboratory or in nature. The purpose of this paper is not to review these phenomena comprehensively, but to provide a starting point for interested readers to refer to related research in areas other than their own.

Ji, Hantao; Kronberg, Philipp; Prager, Stewart C.; Uzdensky, Dmitri A.; CenterMagnetic Self-Organization in Laboratory; Astrophysical Plasmas

2008-05-01

259

Regularities in transient modes in the seismic process according to the laboratory and natural modeling  

Microsoft Academic Search

Regularities in the excitation and relaxation of rock failure were revealed in a series of laboratory experiments. Similar\\u000a regularities are found also in natural conditions. A physical idea and its mathematical description are suggested for explaining\\u000a the obtained experimental data. The aim of the experiments was to understand the character of excitation of the failure, triggered\\u000a by the external impact,

V. B. Smirnov; A. V. Ponomarev; P. Benard; A. V. Patonin

2010-01-01

260

Inorganic carbon acquisition in algal communities: are the laboratory data relevant to the natural ecosystems?  

Microsoft Academic Search

Most of the experimental work on the effects of ocean acidification on the photosynthesis of algae has been performed in the\\u000a laboratory using monospecific cultures. It is frequently assumed that the information obtained from these cultures can be\\u000a used to predict the acclimation response in the natural environment. CO2 concentration is known to regulate the expression and functioning of the

Jesús M. Mercado; F. J. L. Gordillo

261

A Comparison of Water Quality between Natural, Modified, and Manmade Ponds within Brookhaven National Laboratory  

Microsoft Academic Search

Brookhaven National Laboratory (BNL) is located in the center of the Long Island Pine Barrens. Within BNL's 5,265-acre site there are 26 wetlands. Included are coastal plain ponds, vernal ponds, recharge basins, and streams, making it an ideal ecological site to study water chemistry. We tested water samples from seven coastal plain ponds on BNL: four natural (BP1, BP2, BP6,

Priscilla D. Randolph; Roy J. Coomans; Tim Green

262

Antarctic circumpolar wave impact on marine biology: A natural laboratory for climate change study  

Microsoft Academic Search

We use the observed variations in ocean surface chlorophyll, temperature and height caused by the Antarctic Circumpolar Wave (ACW) as a natural laboratory to determine how marine biology responds to changes in ocean stratification in the Southern Ocean. Interannual variations of surface chlorophyll (±5%) observed by SeaWiFS satellite during 1997–2001 vary in phase over the entire Southern Ocean in spite

Corinne Le Quéré; Laurent Bopp; Ina Tegen

2002-01-01

263

Four decades of opposing natural and human-induced artificial selection acting on Windermere pike (Esox lucius)  

Microsoft Academic Search

The ability of natural selection to drive local adaptation has been appreciated ever since Darwin. Whether human impacts can impede the adaptive process has received less attention. We tested this hypothesis by quantifying natural selection and harvest selection acting on a freshwater fish (pike) over four decades. Across the time series, directional natural selection tended to favour large individuals whereas

Stephanie M. Carlson; Eric Edeline; L. Asbjørn Vøllestad; Thrond. O. Haugen; Ian J. Winfield; Janice M. Fletcher; J. Ben James; Nils Chr. Stenseth

2007-01-01

264

Gene flow and the limits to natural selection  

Microsoft Academic Search

In general, individuals who survive to reproduce have genotypes that work relatively well under local conditions. Migrating or dispersing offspring elsewhere is likely to decrease an individual's or its offspring's fitness, not to mention the intrinsic costs and risks of dispersal. Gene flow into a population can counteract gene frequency changes because of selection, imposing a limit on local adaptation.

Thomas Lenormand

2002-01-01

265

Parental assessment and treatment of food selectivity in natural settings.  

PubMed Central

This study evaluated the effects of a parent-conducted functional analysis and treatment consisting of differential reinforcement of an alternative behavior, escape extinction, and demand fading on food selectivity in a young child with autism. Increases in food acceptance at home and in a restaurant were obtained. PMID:14596582

Najdowski, Adel C; Wallace, Michele D; Doney, Janice K; Ghezzi, Patrick M

2003-01-01

266

From prebiotic chemistry to cellular metabolism--the chemical evolution of metabolism before Darwinian natural selection.  

PubMed

It is generally assumed that the complex map of metabolism is a result of natural selection working at the molecular level. However, natural selection can only work on entities that have three basic features: information, metabolism and membrane. Metabolism must include the capability of producing all cellular structures, as well as energy (ATP), from external sources; information must be established on a material that allows its perpetuity, in order to safeguard the goals achieved; and membranes must be able to preserve the internal material, determining a selective exchange with external material in order to ensure that both metabolism and information can be individualized. It is not difficult to understand that protocellular entities that boast these three qualities can evolve through natural selection. The problem is rather to explain the origin of such features under conditions where natural selection could not work. In the present work we propose that these protocells could be built by chemical evolution, starting from the prebiotic primordial soup, by means of chemical selection. This consists of selective increases of the rates of certain specific reactions because of the kinetic or thermodynamic features of the process, such as stoichiometric catalysis or autocatalysis, cooperativity and others, thereby promoting their prevalence among the whole set of chemical possibilities. Our results show that all chemical processes necessary for yielding the basic materials that natural selection needs to work may be achieved through chemical selection, thus suggesting a way for life to begin. PMID:18160077

Meléndez-Hevia, Enrique; Montero-Gómez, Nancy; Montero, Francisco

2008-06-01

267

Convolution Kernels with Feature Selection for Natural Language Processing Tasks  

Microsoft Academic Search

Convolution kernels, such as sequence and tree ker- nels, are advantageous for both the concept and ac- curacy of many natural language processing (NLP) tasks. Experiments have, however, shown that the over-fitting problem often arises when these ker- nels are used in NLP tasks. This paper discusses this issue of convolution kernels, and then proposes a new approach based on

Jun Suzuki; Hideki Isozaki; Eisaku Maeda

2004-01-01

268

Web Resource Selection for Dialogue System Generating Natural Responses  

Microsoft Academic Search

\\u000a Using Web information in example-based dialogue systems is considered to be a good way to increase the topical relevance of\\u000a system responses. However, Web content is mostly written documents, not colloquial utterances. To alleviate the discrepancy\\u000a in style between written and spoken language, we suggest that the corpus should be selected subsets of the Web, viz., online\\u000a bulletin boards. The

Masashi Inoue; Takuya Matsuda; Shoichi Yokoyama

269

Natural selection of altruism in inelastic viscous homogeneous populations  

Microsoft Academic Search

Biological explanations are given of three main uninterpreted theoretical results on the selection of altruism in inelastic viscous homogeneous populations, namely that non-overlapping generations hinder the evolution of altruism, fecundity effects are more conducive to altruism than survival effects, and one demographic regime (so-called death–birth) permits altruism whereas another (so-called birth–death) does not. The central idea is ‘circles of compensation’,

Alan Grafen; Marco Archetti

2008-01-01

270

The Evolution of Recombination: Removing the Limits to Natural Selection  

PubMed Central

One of the oldest hypotheses for the advantage of recombination is that recombination allows beneficial mutations that arise in different individuals to be placed together on the same chromosome. Unless recombination occurs, one of the beneficial alleles is doomed to extinction, slowing the rate at which adaptive mutations are incorporated within a population. We model the effects of a modifier of recombination on the fixation probability of beneficial mutations when beneficial alleles are segregating at other loci. We find that modifier alleles that increase recombination do increase the fixation probability of beneficial mutants and subsequently hitchhike along as the mutants rise in frequency. The strength of selection favoring a modifier that increases recombination is proportional to ?(2)S?r/r when linkage is tight and ?(2)S(3)? r/N when linkage is loose, where ? is the beneficial mutation rate per genome per generation throughout a population of size N, S is the average mutant effect, r is the average recombination rate, and ?r is the amount that recombination is modified. We conclude that selection for recombination will be substantial only if there is tight linkage within the genome or if many loci are subject to directional selection as during periods of rapid evolutionary change. PMID:9335621

Otto, S. P.; Barton, N. H.

1997-01-01

271

Selection for zinc tolerance in fish: results from laboratory and wild populations  

SciTech Connect

A laboratory population of flagfish (Jordanella floridae), selected for zinc tolerance, showed an increased resistance to toxic zinc concentrations after one generation. However, continued selection for three more generations failed to increase tolerance futher, suggesting that acute zinc exposure culled out weak individuals but did not cause genetic changes specifically related to zinc tolerance. Common shiners (Notropis cornutus) inhabiting a zinc-polluted stream were not more zinc tolerant than common shiners from two nearby unpolluted streams, but appeared to be under stress from the chronic exposure to elevated metal levels. These results and a literature review suggest that although fish may have the genetic potential to evolve metal tolerance, they are unable to do so rapidly enough to survive in environments contaminated by human activities.

Rahel, F.J.

1981-01-01

272

Biochemical characterization of chlorantraniliprole and spinetoram resistance in laboratory-selected obliquebanded leafroller, Choristoneura rosaceana (Harris)(Lepidoptera:Tortricidae)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Neonate larvae of obliquebanded leafroller, Choristoneura rosaceana, from a laboratory colony were exposed to two reduced-risk insecticides, chlorantraniliprole and spinetoram. After nine generations of selection, significant levels of resistance to each insecticide were observed. Biochemical assa...

273

Natural family planning and sex selection: fact or fiction?  

PubMed

Determining sex of offspring by timing of intercourse has been a subject of intense interest for the lay public and professional community. This metaaanalysis of couples practicing natural family planning provides an opportunity to evaluate sex ratios in relation to the timing of conception with several parameters, including basal body temperature shift and peak mucus as markers of ovulation. Data from six studies show a statistically significant lower proportion of male births among conceptions that occur during the most fertile time of the cycle. PMID:1836712

Gray, R H

1991-12-01

274

Climate change and geothermal ecosystems: natural laboratories, sentinel systems, and future refugia.  

PubMed

Understanding and predicting how global warming affects the structure and functioning of natural ecosystems is a key challenge of the 21st century. Isolated laboratory and field experiments testing global change hypotheses have been criticized for being too small-scale and overly simplistic, whereas surveys are inferential and often confound temperature with other drivers. Research that utilizes natural thermal gradients offers a more promising approach and geothermal ecosystems in particular, which span a range of temperatures within a single biogeographic area, allow us to take the laboratory into nature rather than vice versa. By isolating temperature from other drivers, its ecological effects can be quantified without any loss of realism, and transient and equilibrial responses can be measured in the same system across scales that are not feasible using other empirical methods. Embedding manipulative experiments within geothermal gradients is an especially powerful approach, informing us to what extent small-scale experiments can predict the future behaviour of real ecosystems. Geothermal areas also act as sentinel systems by tracking responses of ecological networks to warming and helping to maintain ecosystem functioning in a changing landscape by providing sources of organisms that are preadapted to different climatic conditions. Here, we highlight the emerging use of geothermal systems in climate change research, identify novel research avenues, and assess their roles for catalysing our understanding of ecological and evolutionary responses to global warming. PMID:24729541

O'Gorman, Eoin J; Benstead, Jonathan P; Cross, Wyatt F; Friberg, Nikolai; Hood, James M; Johnson, Philip W; Sigurdsson, Bjarni D; Woodward, Guy

2014-11-01

275

Natural Selection on Hippocampal Circuitry Underlying Exploratory Behaviour in Mice: Quantitative-Genetic Analysis  

Microsoft Academic Search

\\u000a Behaviour is an animal’s way of interacting with its environment and it is therefore a prime target for natural selection.\\u000a As behaviour is the output of an animal’s nervous system, this indirectly leads to selection pressures on neuronal structures.\\u000a In consequence, each species’ behaviour and nervous system have co-evolved in the context of its natural habitat and can be\\u000a properly

W. E. Crusio

276

Phenotypic heterogeneity is a selected trait in natural yeast populations subject to environmental stress  

PubMed Central

Populations of genetically uniform microorganisms exhibit phenotypic heterogeneity, where individual cells have varying phenotypes. Such phenotypes include fitness-determining traits. Phenotypic heterogeneity has been linked to increased population-level fitness in laboratory studies, but its adaptive significance for wild microorganisms in the natural environment is unknown. Here, we addressed this by testing heterogeneity in yeast isolates from diverse environmental sites, each polluted with a different principal contaminant, as well as from corresponding control locations. We found that cell-to-cell heterogeneity (in resistance to the appropriate principal pollutant) was prevalent in the wild yeast isolates. Moreover, isolates with the highest heterogeneity were consistently observed in the polluted environments, indicating that heterogeneity is positively related to survival in adverse conditions in the wild. This relationship with survival was stronger than for the property of mean resistance (IC50) of an isolate. Therefore, heterogeneity could be the major determinant of microbial survival in adverse conditions. Indeed, growth assays indicated that isolates with high heterogeneities had a significant competitive advantage during stress. Analysis of yeasts after cultivation for ??500 generations additionally showed that high heterogeneity evolved as a heritable trait during stress. The results showed that environmental stress selects for wild microorganisms with high levels of phenotypic heterogeneity. PMID:24000788

Holland, Sara L; Reader, Tom; Dyer, Paul S; Avery, Simon V

2014-01-01

277

Selection of yeasts with multifunctional features for application as starters in natural black table olive processing.  

PubMed

Yeasts are unicellular eukaryotic microorganisms with a great importance in the elaboration on many foods and beverages. In the last years, researches have focused their attention to determine the favourable effects that these microorganisms could provide to table olive processing. In this context, the present study assesses, at laboratory scale, the potential technological (resistance to salt, lipase, esterase and ?-glucosidase activities) and probiotic (phytase activity, survival to gastric and pancreatic digestions) features of 12 yeast strains originally isolated from Greek natural black table olive fermentations. The multivariate classification analysis carried out with all information obtained (a total of 336 quantitative input data), revealed that the most promising strains (clearly discriminated from the rest of isolates) were Pichia guilliermondii Y16 (which showed overall the highest resistance to salt and simulated digestions) and Wickerhamomyces anomalus Y18 (with the overall highest technological enzymatic activities), while the rest of strains were grouped together in two clearly differentiated clusters. Thus, this work opens the possibility for the evaluation of these two selected yeasts as multifunctional starters, alone or in combination with lactic acid bacteria, in real table olive fermentations. PMID:25475268

Bonatsou, S; Benítez, A; Rodríguez-Gómez, F; Panagou, E Z; Arroyo-López, F N

2015-04-01

278

Developments of the Price equation and natural selection under uncertainty.  

PubMed Central

Many approaches to the study of adaptation, following Darwin, centre on the number of offspring of individuals. Population genetics theory makes clear that predicting gene frequency changes requires more detailed knowledge, for example of linkage and linkage disequilibrium and mating systems. Because gene frequency changes underlie adaptation, this can lead to a suspicion that approaches ignoring these sophistications are approximate or tentative or wrong. Stochastic environments and sexual selection are two topics in which there are widespread views that focusing on number of offspring of individuals is not enough, and that proper treatments require the introduction of further details, namely variability in offspring number and linkage disequilibrium, respectively. However, the bulk of empirical research on adaptation and a great deal of theoretical work continue to employ these approaches. Here, a new theoretical development arising from the Price equation provides a formal justification in very general circumstances for focusing on the arithmetic average of the relative number of offspring of individuals. PMID:10902688

Grafen, A

2000-01-01

279

Heterochrony in limb evolution: developmental mechanisms and natural selection.  

PubMed

The tetrapod limb provides several examples of heterochrony-changes in the timing of developmental events. These include species differences in the sequence of skeletal chondrogenesis, in gene transcription in the developing limbs, and in the relative time at which forelimb and hind limb buds develop. Here, we examine (i) phylogenetic trends in limb heterochrony; (ii) changes in developmental mechanisms that may lead to heterochrony; and (iii) the possible role that heterochrony plays in generating adaptive traits. We analyze the published literature and present preliminary data on turtle (Emys orbicularis) and bat (Rousettus amplexicaudatus) limb development. Teleosts, marsupials, and some urodeles show extreme timing differences between forelimb (or pectoral fin) and hind limb (or pelvic fin) development; this heterochrony may, in some cases, be adaptive. Published data on limb chondrogenesis reveal sequence elements that are strongly conserved (possibly owing to constraints); and others that vary between higher taxa (for unknown reasons). We find little evidence that chondrogenic sequences are modified by selection for limb functional traits. There are a few examples of developmental mechanisms that may be modified under heterochrony to produce adaptive changes in the limb (e.g. some cases of hyperphalangy or limb reduction). In conclusion, numerous examples of limb heterochrony have been recorded. However, few cases are obviously adaptive. Indeed, current data and methodologies make it difficult to identify the developmental changes, or selective pressures, that may underlie limb heterochrony. More integrative studies, including studies of heterochrony within populations, are needed to assess the role of timing shifts in limb evolution. PMID:19130597

Richardson, Michael K; Gobes, Sharon M H; van Leeuwen, Anne C; Polman, Japke A E; Pieau, Claude; Sánchez-Villagra, Marcelo R

2009-09-15

280

Affective Neuronal Selection: The Nature of the Primordial Emotion Systems  

PubMed Central

Based on studies in affective neuroscience and evolutionary psychiatry, a tentative new proposal is made here as to the nature and identification of primordial emotional systems. Our model stresses phylogenetic origins of emotional systems, which we believe is necessary for a full understanding of the functions of emotions and additionally suggests that emotional organizing systems play a role in sculpting the brain during ontogeny. Nascent emotional systems thus affect cognitive development. A second proposal concerns two additions to the affective systems identified by Panksepp. We suggest there is substantial evidence for a primary emotional organizing program dealing with power, rank, dominance, and subordination which instantiates competitive and territorial behavior and is an evolutionary contributor to self-esteem in humans. A program underlying disgust reactions which originally functioned in ancient vertebrates to protect against infection and toxins is also suggested. PMID:23316177

Toronchuk, Judith A.; Ellis, George F. R.

2013-01-01

281

Synonymous Codon Usage in Drosophila melanogaster: Natural Selection and Translational Accuracy  

Microsoft Academic Search

I present evidence that natural selection biases synonymous codon usage to enhance the accuracy of protein synthesis in Drosophila melanogaster. Since the fitness cost of a translational misincorporation will depend on how the amino acid substitution affects protein function, selection for translational accuracy predicts an association between codon usage in DNA and functional constraint at the protein level. The frequency

Hiroshi Akashi

1994-01-01

282

Probabilistic optimization of phenotype distributions: a general solution for the effects of uncertainty on natural selection?  

Microsoft Academic Search

Summary Explorations of optimizing selection often find discrepancies between the theoretically expected and observed phenotypes. Such discrepancies are usually attributed to a variety of potential constraints. We suggest that one common constraint, environmental uncertainty, may reduce the applicability of traditional deterministic or stochastic optimization methods and that many apparent discrepancies might be artifacts of these methods. Since natural selection is

Jin Yoshimura; William M. Shields

1987-01-01

283

Genic and genotypic frequencies of endosperm mutants in maize populations under natural selection  

Microsoft Academic Search

The genic and genotypic frequencies of four maize endosperm mutants, opaque 2 (o2), shrunken 2 (sh2), sugary (su), and waxy (wx), which alter protein, sugar, sol- uble polysaccharides, and starchy fractions, respectively, were monitored through- out five successive generations in synthetic populations of the same genetic back- ground under natural selection. The effect of selection was studied in the vegetative

M. E. Q. P. Martins; W. J. da Silva

1998-01-01

284

Evaluating the role of natural selection in the evolution of gene regulation  

Microsoft Academic Search

Surveys of gene expression reveal extensive variability both within and between a wide range of species. Compelling cases have been made for adaptive changes in gene regulation, but the proportion of expression divergence attributable to natural selection remains unclear. Distinguish- ing adaptive changes driven by positive selection from neutral divergence resulting from mutation and genetic drift is critical for understanding

JC Fay; PJ Wittkopp

2007-01-01

285

Evaluating the role of natural selection in the evolution of gene regulation  

Microsoft Academic Search

Surveys of gene expression reveal extensive variability both within and between a wide range of species. Compelling cases have been made for adaptive changes in gene regulation, but the proportion of expression divergence attributable to natural selection remains unclear. Distinguishing adaptive changes driven by positive selection from neutral divergence resulting from mutation and genetic drift is critical for understanding the

J C Fay; P J Wittkopp

2008-01-01

286

FOVEATED ANALYSIS AND SELECTION OF VISUAL FIXATIONS IN NATURAL SCENES Umesh Rajashekar1  

E-print Network

FOVEATED ANALYSIS AND SELECTION OF VISUAL FIXATIONS IN NATURAL SCENES Umesh Rajashekar1 , Ian van provide insights into the mecha- nisms of fixation selection in humans. Using a novel foveated analysis, ballistic eye movements called saccades. Such a foveated visual percep- tion provides for a large field

Rajashekar, Umesh

287

From Ends to Causes (and Back Again) by Metaphor: The Paradox of Natural Selection  

ERIC Educational Resources Information Center

Natural selection is one of the most famous metaphors in the history of science. Charles Darwin used the metaphor and the underlying analogy to frame his ideas about evolution and its main driving mechanism into a full-fledged theory. Because the metaphor turned out to be such a powerful epistemic tool, Darwin naturally assumed that he could also…

Blancke, Stefaan; Schellens, Tammy; Soetaert, Ronald; Van Keer, Hilde; Braeckman, Johan

2014-01-01

288

Anti-UV, Antioxidant Activity and Cytotoxicity of Selected Natural Extracts for Cosmeceuticals  

Microsoft Academic Search

Selected natural extracts formulated as nanostructured glycerol – water mixtures have been in vitro tested in order to establish the optimum balance among cosmetic efficacy\\/human health and ecosafety. In our work, cytotoxicity and antioxidant activity have been studied on the natural extracts of bilberry, red rose, raspberry, hazelnut, wild strawberry, marigold and blackberry. Cytotoxicity effects have been estimated on the

Elena Cremenescu; Maria Giurginca; Andrei Giurginca; Aurelia Meghea

2008-01-01

289

Did Natural Selection or Genetic Drift Produce the Cranial Diversification of Neotropical Monkeys?  

Microsoft Academic Search

A central controversy among biologists is the relative importance of natural selection and genetic drift as creative forces shaping biological diversification (Fisher 1930; Wright 1931). His- torically, this controversy has been an effective engine powering sev- eral evolutionary research programs during the last century (Provine 1989). While all biologists agree that both processes operate in nature to produce evolutionary change,

Gabriel Marroig

2004-01-01

290

Sexual Selection: Furthering the "Evolution" Metaphor Computational evolution is based on biological evolution, primarily using the features of natural  

E-print Network

evolution is based on biological evolution, primarily using the features of natural selection including driving force behind the diversity and complexity of the natural world is sexual selection. Previous for offspring to inherit traits that are selected for. Computational evolution is based on this natural

Meeden, Lisa A.

291

The Genetic Architecture of Ecological Speciation and the Association with Signatures of Selection in Natural Lake Whitefish (Coregonus sp. Salmonidae)  

E-print Network

of the role of divergent natural selection on those traits. The lake whitefish (Coregonus clupeaformis with signatures of selection in nature, providing strong support for the hypothesis that divergent naturalThe Genetic Architecture of Ecological Speciation and the Association with Signatures of Selection

Bernatchez, Louis

292

Cambridge Companion to the Origin of Species, eds. R. Richards and M. Ruse Darwin's Theory of Natural Selection and  

E-print Network

of Natural Selection and Its Moral Purpose Robert J. Richards Thomas Henry Huxley recalled that after he--variability, struggle for existence, adaptation-- form core features of Darwin's conception of natural selection. Thus been interpreted to affirm--that the idea of natural selection was really quite simple and that when

Richards, Robert J.

293

Redox-sensitivity and mobility of selected pharmaceutical compounds in a laboratory column experiment  

NASA Astrophysics Data System (ADS)

Laboratory column experiments are suitable to investigate the sediment water interaction and to study the transport behaviour of solutes. Processes like retardation and degradation can be identified and quantified. The conducted experiment, which is closely connected to a field study in Luxembourg, investigated the transport behaviour of selected pharmaceutical compounds and their redox-dependent metabolism under water saturated conditions. Fine-grained natural sediment with a low hydraulic conductivity from a study site in Luxembourg was filled into the column. The water for the experiment was taken from a small stream at the same fieldsite. It was spiked with four pharmaceutical compounds (carbamazepine, diclofenac, ibuprofen, sulfamethoxazole) with concentrations between 170 and 300 ng/L for the different substances. The chosen pharmaceuticals were also detected in groundwater and surface water samples at the study site and used to qualify exchange/mixing of surface water and groundwater (BANZHAF et al., 2011). As some of the substances are known to exhibit redox-sensitive degradation, the redox-conditions were systematically varied throughout the experiment. This was realised by adding nitrate at the inflow of the column. During the experiment, which lasted for 2.5 months, four different nitrate concentrations (20-130 mg/L) were applied, beginning with the highest concentration. During the experiment water from the reservoir tank was sampled daily in order to detect a potential degradation of the pharmaceutical compounds before they enter the column. The effluent water was sampled every three hours to guarantee a maximum resolution for the analysis of the pharmaceuticals where necessary. In addition, major ions were analysed in the influent and effluent samples. Throughout the experiment physicochemical parameters (oxidation reduction potential (ORP), dissolved oxygen, electrical conductivity, and pH-value) were measured and logged at the outflow of the column. At the beginning, the ORP was positive (200 mV) and then dropped continuously. Negative values were reached after 1 month and at the end of the experiment -300 mV were measured. Apart from nitrate and nitrite no significant changes in ion concentrations were detected in the effluent. However, the added pharmaceuticals showed very different behaviour in the column. Diclofenac and especially carbamazepine were highly absorbed by the sediment. They were detected significantly later at the outflow of the column than sulfamethoxazole and ibuprofen. Sulfamethoxazole was heavily influenced by the redox-conditions. Its time variation curve in the effluent is negatively correlated with nitrite and nitrate: during nitrite formation the concentrations of sulfamethoxazole dropped considerably. The presented experiment yields a better understanding of the processes influencing the occurrence and transport behaviour of the studied compounds. In addition, some general findings on redox-dependent transport behaviour and metabolism of the antibiotic sulfamethoxazole are gained. This emphasizes the role of the ORP as a key parameter for the behaviour of this compound, which has to be considered. BANZHAF, S., KREIN, A. & SCHEYTT, T. (2011). Investigative approaches to determine exchange processes in the hyporheic zone of a low permeability riverbank. Hydrogeology Journal 19 (3), pp. 591-601.

Banzhaf, S.; Nödler, K.; Licha, T.; Krein, A.; Scheytt, T.

2012-04-01

294

Natural selection reduces energy metabolism in the garden snail, helix aspersa (cornu aspersum).  

PubMed

Phenotypic selection is widely recognized as the primary cause of adaptive evolution in natural populations, a fact that has been documented frequently over the last few decades, mainly in morphological and life-history traits. The energetic definition of fitness predicts that natural selection will maximize the residual energy available for growth and reproduction, suggesting that energy metabolism could be a target of selection. To address this problem, we chose the garden snail, Helix aspersa (Cornu aspersum). We performed a seminatural experiment for measuring phenotypic selection on standard metabolic rate (SMR), the minimum cost of maintenance in ectotherm organisms. To discount selection on correlated traits, we included two additional whole-organism performance traits (mean speed and maximum force of dislodgement). We found a combination of linear (negative directional selection, beta=-0.106 +/- 0.06; P= 0.001) and quadratic (stabilizing selection, gamma=-0.012 +/- 0.033; P= 0.061) selection on SMR. Correlational selection was not significant for any possible pair of traits. This suggests that individuals with average-to-reduced SMRs were promoted by selection. To the best of our knowledge, this is the first study showing significant directional selection on the obligatory cost of maintenance in an animal, providing support for the energetic definition of fitness. PMID:19236475

Artacho, Paulina; Nespolo, Roberto F

2009-04-01

295

On the black hole species (by means of natural selection)  

E-print Network

Recently our understanding of black holes in D-spacetime dimensions, as solutions of the Einstein equation, has advanced greatly. Besides the well established spherical black hole we have now explicitly found other species of topologies of the event horizons. Whether in asymptotically flat, AntideSitter or deSitter spaces, the different species are really non-unique when D > 4. An example of this are the black rings. Another issue in higher dimensions that is not fully understood is the struggle for existence of regular black hole solutions. However, we managed to observe a selection rule for regular solutions of thin black rings: they have to be balanced i.e. in vacuum, a neutral asymptotically flat black ring incorporates a balance between the centrifugal repulsion and the tension. The equilibrium condition seems to be equivalent to the condition to guarantee regularity on the geometry of the black ring solution. We will review the tree of species of black holes and present new results on exotic black holes with charges.

Maria J. Rodriguez

2010-03-11

296

Successful sex pre-selection using natural family planning.  

PubMed

The objective of the study was to test the hypothesis that gender can be preselected by timing coitus in relation to ovulation, the marker of ovulation being the Peak symptom according to the Billings Method. A blind prospective study of 99 couples wishing to preselect the sex of their child was conducted in Nigeria, using the Post-Peak approach of Billings Method for males and Pre-Peak for females. Research co-ordinators examined the 'post-conception' form within four months of conception. This form recorded the timing of coitus prior to conception, and from this, the sex of child was predicted. 94 of the couples had a child of pre-selected sex showing a method success of 94.9%. 78 of 81 predicting a male were successful (96.3%) and 16 of the 18 predicting a female (88.9%). There was one user-failure, a couple who wanted a girl, timed coitus as for a boy, which they had. The study indicates that where comprehensive instruction is provided, the sex of a child can be preselected with a high degree of confidence by timing coitus, using the Post-Peak approach of Billings Method for males and Pre-Peak for females. PMID:21987941

McSweeney, Léonie

2011-03-01

297

Assessment of laboratory logistics management information system practice for HIV/AIDS and tuberculosis laboratory commodities in selected public health facilities in Addis Ababa, Ethiopia  

PubMed Central

Introduction Logistics management information system for health commodities remained poorly implemented in most of developing countries. To assess the status of laboratory logistics management information system for HIV/AIDS and tuberculosis laboratory commodities in public health facilities in Addis Ababa. Methods A cross-sectional descriptive study was conducted from September 2010-January 2011 at selected public health facilities. A stratified random sampling method was used to include a total of 43 facilities which, were investigated through quantitative methods using structured questionnaires interviews. Focus group discussion with the designated supply chain managers and key informant interviews were conducted for the qualitative method. Results There exists a well-designed logistics system for laboratory commodities with trained pharmacy personnel, distributed standard LMIS formats and established inventory control procedures. However, majority of laboratory professionals were not trained in LMIS. Majority of the facilities (60.5%) were stocked out for at least one ART monitoring and TB laboratory reagents and the highest stock out rate was for chemistry reagents. Expired ART monitoring laboratory commodities were found in 25 (73.5%) of facilities. Fifty percent (50%) of the assessed hospitals and 54% of health centers were currently using stock/bin cards for all HIV/AIDS and TB laboratory commodities in main pharmacy store, among these only 25% and 20.8% of them were updated with accurate information matching with the physical count done at the time of visit for hospitals and health centers respectively. Conclusion Even though there exists a well designed laboratory LMIS, keeping quality stock/bin cards and LMIS reports were very low. Key ART monitoring laboratory commodities were stock out at many facilities at the day of visit and during the past six months. Based on findings, training of laboratory personnel's managing laboratory commodities and keeping accurate inventory control procedures were recommended. PMID:24106574

Desale, Adino; Taye, Bineyam; Belay, Getachew; Nigatu, Alemayehu

2013-01-01

298

A statistical test for lineage-specific natural selection on quantitative traits based on multiple-line crosses  

E-print Network

A statistical test for lineage-specific natural selection on quantitative traits based on multiple be attributable to natural selection. However, it is a difficult task to quantify the strength of evidence for selection acting on a particular trait. Here we develop a population-genetic test for selection acting

Lässig, Michael

299

SELECTIVE NOx RECIRCULATION FOR STATIONARY LEAN-BURN NATURAL GAS ENGINES  

SciTech Connect

The research program conducted at the West Virginia University Engine and Emissions Research Laboratory (EERL) is working towards the verification and optimization of an approach to remove nitric oxides from the exhaust gas of lean burn natural gas engines. This project was sponsored by the US Department of Energy, National Energy Technology Laboratory (NETL) under contract number: DE-FC26-02NT41608. Selective NOx Recirculation (SNR) involves three main steps. First, NOx is adsorbed from the exhaust stream, followed by periodic desorption from the aftertreatment medium. Finally the desorbed NOx is passed back into the intake air stream and fed into the engine, where a percentage of the NOx is decomposed. This reporting period focuses on the NOx decomposition capability in the combustion process. Although researchers have demonstrated NOx reduction with SNR in other contexts, the proposed program is needed to further understand the process as it applies to lean burn natural gas engines. SNR is in support of the Department of Energy goal of enabling future use of environmentally acceptable reciprocating natural gas engines through NOx reduction under 0.1 g/bhp-hr. The study of decomposition of oxides of nitrogen (NOx) during combustion in the cylinder was conducted on a 1993 Cummins L10G 240 hp lean burn natural gas engine. The engine was operated at different air/fuel ratios, and at a speed of 800 rpm to mimic a larger bore engine. A full scale dilution tunnel and analyzers capable of measuring NOx, CO{sub 2}, CO, HC concentrations were used to characterize the exhaust gas. Commercially available nitric oxide (NO) was used to mimic the NOx stream from the desorption process through a mass flow controller and an injection nozzle. The same quantity of NOx was injected into the intake and exhaust line of the engine for 20 seconds at various steady state engine operating points. NOx decomposition rates were obtained by averaging the peak values at each set point minus the baseline and finding the ratio between the injected NO amounts. It was observed that the air/fuel ratio, injected NO quantity and engine operating points affected the NOx decomposition rates of the natural gas engine. A highest NOx decomposition rate of 27% was measured from this engine. A separate exploratory tests conducted with a gasoline engine with a low air/fuel ratio yielded results that suggested, that high NOx decomposition rates may be possible if a normally lean burn engine were operated at conditions closer to stoichiometric, with high exhaust gas recirculation (EGR) for a brief period of time during the NOx decomposition phase and with a wider range of air/fuel ratios. Chemical kinetic model predictions using CHEMKIN were performed to relate the experimental data with the established rate and equilibrium models. NOx decomposition rates from 35% to 42% were estimated using the CHEMKIN software. This provided insight on how to maximize NOx decomposition rates for a large bore engine. In the future, the modeling will be used to examine the effect of higher NO{sub 2}/NO ratios that are associated with lower speed and larger bore lean burn operation.

Nigel Clark; Gregory Thompson; Richard Atkinson; Chamila Tissera; Matt Swartz; Emre Tatli; Ramprabhu Vellaisamy

2005-01-01

300

Response to selection under controlled environment versus natural selection in diverse regions across Canada  

Technology Transfer Automated Retrieval System (TEKTRAN)

Red clover is a widely adaptable and productive forage legume species found in most temperate regions of the world. To date, specific selection techniques for identifying genotypes with superior persistence have not been successful in improving the general adaptation and the long-term persistence o...

301

Natural Antioxidant Constituents from Selected Aromatic Plants and Their Antimicrobial Activity Against Selected Pathogenic Microorganisms  

Microsoft Academic Search

Summary Aromatic plants contain natural antioxidant constituents such as phenolic compounds, which have attracted a great deal of public and scientific interest because of their health- -promoting effects as antioxidants. Five plants, Filipendula ulmaria (meadow sweet), Cratae- gus monogyna (hawthorn), Polygonum aviculare (polygonum), Potentilla anserina (silverweed), and Pelargonium purpureum (little robin), have been examined in order to determine their phenolic

Charalampos Proestos; Ioannis Spyridon Boziaris; Maria Kapsokefalou; Michael Komaitis

2008-01-01

302

Laboratory selection of carbofuran tolerant line of Culex quinquefasciatus Say, the filarial vector at Mysore.  

PubMed

Carbofuran is a systemic insecticide/nematicide extensively employed in modern agriculture and public health to combat various insect pests and vectors. The development of insecticide resistance due to natural selection pressure by Anopheline and Culicine mosquitoes has created serious repercussions in mosquito control and disease eradication campaigns. In this regard Culex quinquefasciatus, a widely dispersed domestic mosquito and the only vector of lymphatic filariasis in India, was selected for the present experiment. In order to assess the resistance development in this species, it was subjected to carbofuran bioassay by employing WHO method for 10 generations. The results of larval selection test up to F10 revealed a significant increase in tolerance development in every generation compared to the susceptible F1. The results revealed up to 16.225 times tolerance after 10 generations. The LC50 observed in F10 is 1.298 ppm compared to 0.08 ppm in the F1. The implications of the observations will be discussed. PMID:22471184

Aneesh, E M; Vijayan, V A

2010-09-01

303

Evaluation of Cavity Collapse and Surface Crater Formation for Selected Lawrence Livermore National Laboratory Tests - 2011  

SciTech Connect

This report evaluates collapse evolution for selected Lawrence Livermore National Laboratory (LLNL) underground nuclear tests at the Nevada National Security Site (NNSS, formerly called the Nevada Test Site). The work is being done at the request of National Security Technologies, LLC (NSTec) and supports the Department of Energy, National Nuclear Security Administration for the Nevada Site Office Borehole Management Program (BMP). The primary objective of this program is to close (plug) weapons program legacy boreholes that are deemed no longer useful. Safety decisions must be made before a crater area, or potential crater area, can be reentered for any work. Our statements on cavity collapse and crater formation are input into their safety decisions. The BMP is an on-going program to address hundreds of boreholes at the NTS. Each year NSTec establishes a list of holes to be addressed. They request the assistance of the Lawrence Livermore National Laboratory and Los Alamos National Laboratory Containment Programs to provide information related to the evolution of collapse history and make statements on completeness of collapse as relates to surface crater stability. These statements do not include the effects of erosion that may modify the collapse craters over time. They also do not address possible radiation dangers that may be present. Subject matter experts from the LLNL Containment Program who had been active in weapons testing activities performed these evaluations. Information used included drilling and hole construction, emplacement and stemming, timing and sequence of the selected test and nearby tests, geology, yield, depth of burial, collapse times, surface crater sizes, cavity and crater volume estimations, ground motion, and radiological release information. Both classified and unclassified data were reviewed. Various amounts of information are available for these tests, depending on their age and other associated activities. Lack of data can hamper evaluations and introduce uncertainty. We make no attempt to quantify this uncertainty. The following unclassified summary statements describe collapse evolution and crater stability in response to a recent request to review 3 LLNL test locations in areas 2 and 12: Kennebec in U2af, Cumberland in U2e, and Yuba in U12b.10.

Pawloski, G A

2011-02-28

304

NATURAL SELECTION VS. RANDOM DRIFT: EVIDENCE FROM TEMPORAL VARIATION IN ALLELE FREQUENCIES IN NATURE  

Microsoft Academic Search

We have obtained monthly samples of two species, Drosophila pseudoobscura and Drosophila persimilis, in a natural population from Napa County, California. In each species, about 300 genes have been assayed by electrophoresis for each of seven enzyme loci in each monthly sample from March 1972 to June 1975. Using statistical methods developed for the purpose, we have examined whether the

LAURENCE D. MUELLER; LORRAINE G. BARR; FRANCISCO J. AYALA

305

Image statistics underlying natural texture selectivity of neurons in macaque V4.  

PubMed

Our daily visual experiences are inevitably linked to recognizing the rich variety of textures. However, how the brain encodes and differentiates a plethora of natural textures remains poorly understood. Here, we show that many neurons in macaque V4 selectively encode sparse combinations of higher-order image statistics to represent natural textures. We systematically explored neural selectivity in a high-dimensional texture space by combining texture synthesis and efficient-sampling techniques. This yielded parameterized models for individual texture-selective neurons. The models provided parsimonious but powerful predictors for each neuron's preferred textures using a sparse combination of image statistics. As a whole population, the neuronal tuning was distributed in a way suitable for categorizing textures and quantitatively predicts human ability to discriminate textures. Together, we suggest that the collective representation of visual image statistics in V4 plays a key role in organizing the natural texture perception. PMID:25535362

Okazawa, Gouki; Tajima, Satohiro; Komatsu, Hidehiko

2015-01-27

306

Image statistics underlying natural texture selectivity of neurons in macaque V4  

PubMed Central

Our daily visual experiences are inevitably linked to recognizing the rich variety of textures. However, how the brain encodes and differentiates a plethora of natural textures remains poorly understood. Here, we show that many neurons in macaque V4 selectively encode sparse combinations of higher-order image statistics to represent natural textures. We systematically explored neural selectivity in a high-dimensional texture space by combining texture synthesis and efficient-sampling techniques. This yielded parameterized models for individual texture-selective neurons. The models provided parsimonious but powerful predictors for each neuron’s preferred textures using a sparse combination of image statistics. As a whole population, the neuronal tuning was distributed in a way suitable for categorizing textures and quantitatively predicts human ability to discriminate textures. Together, we suggest that the collective representation of visual image statistics in V4 plays a key role in organizing the natural texture perception. PMID:25535362

Okazawa, Gouki; Tajima, Satohiro; Komatsu, Hidehiko

2015-01-01

307

Testing natural selection vs. genetic drift in phenotypic evolution using quantitative trait locus data.  

PubMed

Evolutionary biologists have long sought a way to determine whether a phenotypic difference between two taxa was caused by natural selection or random genetic drift. Here I argue that data from quantitative trait locus (QTL) analyses can be used to test the null hypothesis of neutral phenotypic evolution. I propose a sign test that compares the observed number of plus and minus alleles in the "high line" with that expected under neutrality, conditioning on the known phenotypic difference between the taxa. Rejection of the null hypothesis implies a role for directional natural selection. This test is applicable to any character in any organism in which QTL analysis can be performed. PMID:9691061

Orr, H A

1998-08-01

308

Seismic and geodetic signatures of fault slip at the Slumgullion Landslide Natural Laboratory  

NASA Astrophysics Data System (ADS)

We tested the hypothesis that the Slumgullion landslide is a useful natural laboratory for observing fault slip, specifically that slip along its basal surface and side-bounding strike-slip faults occurs with comparable richness of aseismic and seismic modes as along crustal- and plate-scale boundaries. Our study provides new constraints on models governing landslide motion. We monitored landslide deformation with temporary deployments of a 29-element prism array surveyed by a robotic theodolite and an 88-station seismic network that complemented permanent extensometers and environmental instrumentation. Aseismic deformation observations show that large blocks of the landslide move steadily at approximately centimeters per day, possibly punctuated by variations of a few millimeters, while localized transient slip episodes of blocks less than a few tens of meters across occur frequently. We recorded a rich variety of seismic signals, nearly all of which originated outside the monitoring network boundaries or from the side-bounding strike-slip faults. The landslide basal surface beneath our seismic network likely slipped almost completely aseismically. Our results provide independent corroboration of previous inferences that dilatant strengthening along sections of the side-bounding strike-slip faults controls the overall landslide motion, acting as seismically radiating brakes that limit acceleration of the aseismically slipping basal surface. Dilatant strengthening has also been invoked in recent models of transient slip and tremor sources along crustal- and plate-scale faults suggesting that the landslide may indeed be a useful natural laboratory for testing predictions of specific mechanisms that control fault slip at all scales.

Gomberg, Joan; Schulz, William; Bodin, Paul; Kean, Jason

2011-09-01

309

Quasi Dominance Rough Set Approach in Testing for Traces of Natural Selection at Molecular Level  

Microsoft Academic Search

Testing for natural selection operating at molecular level has become one of the important issues in contemporary bioinformatics.\\u000a In the paper the novel methodology called quasi dominance rough set approach (QDRSA) is proposed and applied for testing of\\u000a balancing selection in four genes involved in human familial cancer. QDRSA can be considered as a hybrid of classical rough\\u000a set approach

Krzysztof A. Cyran

310

Natural Selection  

NSDL National Science Digital Library

The concept of interdependence in an ecosystem and its effect on the evolution of populations is further explored through a model of a dam. Students build a dam in the middle of the field, dividing the ecosystem in half to illustrate the affects of geographic isolation. They watch as the grass and then the rabbit populations in that region shift to one variant in the population. When students remove the dam, they observe the ecosystem slowly return to its original state.

Consortium, The C.

2011-12-11

311

In situ and laboratory toxicity of coalbed natural gas produced waters with elevated sodium bicarbonate  

USGS Publications Warehouse

Some tributaries in the Powder River Structural Basin, USA, were historically ephemeral, but now contain water year round as a result of discharge of coalbed natural gas (CBNG)-produced waters. This presented the opportunity to study field sites with 100% effluent water with elevated concentrations of sodium bicarbonate. In situ experiments, static renewal experiments performed simultaneously with in situ experiments, and static renewal experiments performed with site water in the laboratory demonstrated that CBNG-produced water reduces survival of fathead minnow (Pimephales promelas) and pallid sturgeon (Scaphirhynchus albus). Age affected survival of fathead minnow, where fish 2 d posthatch (dph) were more sensitive than 6 dph fish, but pallid sturgeon survival was adversely affected at both 4 and 6 dph. This may have implications for acute assays that allow for the use of fish up to 14 dph. The survival of early lifestage fish is reduced significantly in the field when concentrations of NaHCO3 rise to more than 1500?mg/L (also expressed as >1245?mg HCO3 (-) /L). Treatment with the Higgin's Loop technology and dilution of untreated water increased survival in the laboratory. The mixing zones of the 3 outfalls studied ranged from approximately 800?m to 1200?m below the confluence. These experiments addressed the acute toxicity of effluent waters but did not address issues related to the volumes of water that may be added to the watershed.

Farag, Aida M.; Harper, David D.; Skaar, Don

2014-01-01

312

Complexation of transuranic ions by humic substances: Application of laboratory results to the natural system  

SciTech Connect

Environmental investigations show transuranic ions sorb to humic substances. The resulting species are often mobile and are expected to be important vectors in the migration of transuranic ions in natural systems. However, these environmental studies yield no quantitative data useful for modeling. Laboratory complexation experiments with transuranic ions and humic substances generate thermodynamic data required for complexation modeling. The data presented in this work are based on the metal ion charge neutralization model, which is briefly described. When a consistent complexation model is used, similar results are obtained from different experimental conditions, techniques, and laboratories. Trivalent transuranic ions (Cm(III), Am(III)) have been extensively studied with respect to pH, ionic strength, origin of humic acid, and mixed species formation. The complexation of Np(V) has been examined over a large pH and metal ion concentration range with different humic acids. Some data does exist on the complexation ion concentration range with different humic acids. Some data does exist on the complexation of plutonium with humic acid, however further work is needed. Calculations on the Gorleben aquifer system using the thermodynamic data are presented. Critical information lacking from the thermodynamic database is identified. 55 refs., 2 figs., 3 tabs.

Czerwinski, K. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Nuclear Engineering Dept.; Kim, J. [Forschungszentrum Karlsruhe (Germany). Inst. fuer Entsorgungstechnik

1997-12-31

313

Strong natural selection during plant restoration favors an unexpected suite of plant traits.  

PubMed

RESTORATION IS AN OPPORTUNITY TO STUDY NATURAL SELECTION: One can measure the distribution of traits in source propagules used to found populations, compare this with the distribution of traits in successful recruits, and determine the strength and direction of selection on potentially adaptive traits. We investigated whether natural selection influenced seedling establishment during postfire restoration in the Great Basin, an area where large-scale restoration occurs with a few widely available cultivars planted over a large range of environmental conditions. We collected seeds from established plants of the perennial grass Elymus elymoides ssp. californicus (squirreltail) at two restoration sites and compared the distribution of phenotypic traits of surviving plants with the original pool of restoration seeds. Seeds were planted in common gardens for two generations. Plants grown from seeds that established in the field were a nonrandom subset of the original seeds, with directional selection consistently favoring a correlated suite of traits in both field sites: small plant and seed size, and earlier flowering phenology. These results demonstrate that natural selection can affect restoration establishment in strong and predictable ways and that adaptive traits in these sites were opposite of the current criteria used for selection of restoration material in this system. PMID:23745142

Kulpa, Sarah M; Leger, Elizabeth A

2013-04-01

314

From Ends to Causes (and Back Again) by Metaphor: The Paradox of Natural Selection  

NASA Astrophysics Data System (ADS)

Natural selection is one of the most famous metaphors in the history of science. Charles Darwin used the metaphor and the underlying analogy to frame his ideas about evolution and its main driving mechanism into a full-fledged theory. Because the metaphor turned out to be such a powerful epistemic tool, Darwin naturally assumed that he could also employ it as an educational tool to inform his contemporaries about his findings. Moreover, by using the metaphor Darwin was able to bring his theory in accordance with both the dominant philosophy of science in his time and the respected tradition of natural theology. However, as he introduced his theory of evolution by natural selection in On the origin of species in 1859, the metaphor also turned out to have a serious downside. Because of its intentional overtones, his contemporaries systematically misunderstood his metaphor not as a natural mechanism causing evolution to occur but as an agent who works towards particular ends. The difference in success between natural selection as an epistemic tool and its failure as an educational tool is labelled as a paradox. We explain the paradox from a cognitive perspective and discuss the implications for teaching evolution.

Blancke, Stefaan; Schellens, Tammy; Soetaert, Ronald; Van Keer, Hilde; Braeckman, Johan

2014-04-01

315

Selection of an omnivorous diet by the mangrove tree crab Aratus pisonii in laboratory experiments  

NASA Astrophysics Data System (ADS)

Observational studies on leaf damage, gut content analyses, and crab behaviour have demonstrated that like numerous other mangrove and salt-marsh generalists, the mangrove tree crab Aratus pisonii feeds on a variety of food resources. This study is the first that experimentally tests feeding preferences of A. pisonii, as well as the first to test experimentally whether chemical composition of food resources is responsible for food selection. Feeding preferences were determined among a variety of plant, algal, and animal resources available in the field both in Florida and Belize, using multiple-choice feeding assays, where male and female crabs simultaneously were offered a variety of food items. To test whether chemistry of food resources was responsible for feeding preferences, chemical extracts of food resources were incorporated in an agar-based artificial food, and used in feeding assays. Results of feeding assays suggest that crabs prefer animal matter from ˜ 2.5 to 13× more than other available resources, including leaves of the red mangrove Rhizophora mangle, which contribute the most to their natural diet. Artificial feeding assays also demonstrated that chemical cues were responsible for selection of animal matter, up to 25× more than other available resources. Non-polar extracts (derived from extraction in 1:1 ethyl actetate:methanol) stimulated feeding the most, suggesting that fatty acids, triglycerides, or sterols may be important for growth, reproduction, or survival. Results for both sexes were similar across most assays. While chemical composition of food resources appears to play some role in selection, this does not discount the potential role of other factors, such as resource availability, competition, predation, or reproductive requirements in influencing feeding preferences. Bioassay-guided fractionation of extracts should aid in determining chemical constituents that play the greatest role in determining feeding preferences.

Erickson, Amy A.; Feller, Ilka C.; Paul, Valerie J.; Kwiatkowski, Lisa M.; Lee, Woody

2008-02-01

316

Natural attenuation of pharmaceuticals and an illicit drug in a laboratory column experiment.  

PubMed

Trace amounts of pharmaceutical compounds have been detected in waters across the United States. Many compounds are released as the result of human ingestion and subsequent excretion of over-the-counter and prescription medications, and illicit drugs. This research utilized columns (30×30cm) of sand and undisturbed fine-grained sediments to simulate injection of wastewater containing pharmaceuticals and an illicit drug, such as would be found in a septic system, leaky sewer, or landfill. The columns were placed in a temperature-controlled laboratory and each was injected with natural groundwater containing known concentrations of caffeine, methamphetamine, and acetaminophen. Natural attenuation of each chemical was observed in all columns. The highest amount removed (approximately 90%) occurred in the undisturbed column injected with methamphetamine, compared with little reduction in the sand column. When the suite of drugs was injected, loss of methamphetamine was less than when methamphetamine was injected alone. The subsurface sediments exhibit the ability to remove a substantial amount of the injected pharmaceuticals and illicit drug; however, complete removal was not achieved. There was little attenuation of injected pharmaceuticals in the sand column which demonstrates a concern for water quality in the environment if pharmaceuticals were to contaminate a sandy aquifer. Understanding the transport of pharmaceuticals in the subsurface environment is an important component of protecting drinking water supplies from contamination. PMID:24594486

Greenhagen, Andrew M; Lenczewski, Melissa E; Carroll, Monica

2014-11-01

317

Differential effects of inbreeding and selection on male reproductive phenotype associated with the colonization and laboratory maintenance of Anopheles gambiae  

PubMed Central

Background Effective mating between laboratory-reared males and wild females is paramount to the success of vector control strategies aiming to decrease disease transmission via the release of sterile or genetically modified male mosquitoes. However mosquito colonization and laboratory maintenance have the potential to negatively affect male genotypic and phenotypic quality through inbreeding and selection, which in turn can decrease male mating competitiveness in the field. To date, very little is known about the impact of those evolutionary forces on the reproductive biology of mosquito colonies and how they ultimately affect male reproductive fitness. Methods Here several male reproductive physiological traits likely to be affected by inbreeding and selection following colonization and laboratory rearing were examined. Sperm length, and accessory gland and testes size were compared in male progeny from field-collected females and laboratory strains of Anopheles gambiae sensu stricto colonized from one to over 25 years ago. These traits were also compared in the parental and sequentially derived, genetically modified strains produced using a two-phase genetic transformation system. Finally, genetic crosses were performed between strains in order to distinguish the effects of inbreeding and selection on reproductive traits. Results Sperm length was found to steadily decrease with the age of mosquito colonies but was recovered in refreshed strains and crosses between inbred strains therefore incriminating inbreeding costs. In contrast, testes size progressively increased with colony age, whilst accessory gland size quickly decreased in males from colonies of all ages. The lack of heterosis in response to crossing and strain refreshing in the latter two reproductive traits suggests selection for insectary conditions. Conclusions These results show that inbreeding and selection differentially affect reproductive traits in laboratory strains overtime and that heterotic ‘supermales’ could be used to rescue some male reproductive characteristics. Further experiments are needed to establish the exact relationship between sperm length, accessory gland and testes size, and male reproductive success in the laboratory and field settings. PMID:24418094

2014-01-01

318

2002 Nature Publishing Group Selective cell suicide is crucial for sculpting the embryo,  

E-print Network

© 2002 Nature Publishing Group REVIEWS Selective cell suicide is crucial for sculpting the embryo apoptosis is a crucial step in tumorigenesis. Indeed, a defective suicide programme endows nascent-being and decide whether the suicide pro- gramme should be activated? Re-evaluation of this hotly debated issue8

Gauthier, Eric

319

The Interface Theory of Perception: Natural Selection Drives True Perception To Swift Extinction  

E-print Network

The Interface Theory of Perception: Natural Selection Drives True Perception To Swift Extinction Donald D. Hoffman #12;#12;1 The Interface Theory of Perception A goal of perception is to estimate true shaped our senses to this end. These three assumptions motivate much work on human perception. I here

Stanford, Kyle

320

Natural and sexual selection against immigrants maintains differentiation among micro-allopatric populations  

Microsoft Academic Search

Local adaptation to divergent environmental conditions can promote popu- lation genetic differentiation even in the absence of geographic barriers and hence lead to speciation. But what mechanisms contribute to reproductive isolation among diverging populations? We tested for natural and sexual selection against immigrants in a fish species inhabiting (and adapting to) nonsulphidic surface habitats, sulphidic surface habitats and a sulphidic

M. TOBLER; R. RIESCH; C. M. TOBLER; T. SCHULZ-MIRBACH

2009-01-01

321

Thermodynamics of natural selection III: Landauer's principle in computation and chemistry  

Microsoft Academic Search

This is the third in a series of three papers devoted to energy flow and entropy changes in chemical and biological processes, and their relations to the thermodynamics of computation. The previous two papers have developed reversible chemical transformations as idealizations for studying physiology and natural selection, and derived bounds from the second law of thermodynamics, between information gain in

Eric Smith

2008-01-01

322

Nullomers: Really a Matter of Natural Selection? Claudia Acquisti1,2  

E-print Network

, Tempe, Arizona, United States of America, 2 The Biodesign Institute and the School of Life Sciences identification, pesticide development, environmental monitoring, and forensic applications has been envisioned S (2007) Nullomers: Really a Matter of Natural Selection?. PLoS ONE 2(10): e1022. doi:10.1371/ journal

Kumar, Sudhir

323

Evolving Better Cars: Teaching Evolution by Natural Selection with a Digital Inquiry Activity  

ERIC Educational Resources Information Center

Evolutionary experiments are usually difficult to perform in the classroom because of the large sizes and long timescales of experiments testing evolutionary hypotheses. Computer applications give students a window to observe evolution in action, allowing them to gain comfort with the process of natural selection and facilitating inquiry…

Royer, Anne M.; Schultheis, Elizabeth H.

2014-01-01

324

Darwin's Arguments in Favour of Natural Selection and against Special Creationism  

ERIC Educational Resources Information Center

In many places in "The Origin of Species", Darwin compares his own theory of Natural Selection favourably with Special Creationism which comes off as a bad second best. He does this using some version of the argument form known as "Inference to the Best Explanation". The first part of this paper is methodological. It considers Whewell's notion of…

Nola, Robert

2013-01-01

325

Approximating Nature's Variation: Selecting and Using Reference Information in Restoration Ecology  

Microsoft Academic Search

Restoration ecologists use reference information to define restoration goals, determine the restoration po- tential of sites, and evaluate the success of restoration efforts. Basic to the selection and use of reference in- formation is the need to understand temporal and spatial variation in nature. This is a challenging task: variation is likely to be scale dependent; ecosystems vary in complex

Peter S. White; Joan L. Walker

1997-01-01

326

Interrogating a High-Density SNP Map for Signatures of Natural Selection  

Microsoft Academic Search

Identifying genomic regions that have been targets of natural selection remains one of the most important and challenging areas of research in genetics. To this end, we report an analysis of 26,530 single nucleotide polymorphisms (SNPs) with allele frequencies that were determined in three populations. Specifically, we calculated a measure of genetic differentiation, FST, for each locus and examined its

Joshua M. Akey; Ge Zhang; Kun Zhang; Li Jin; Mark D. Shriver

2002-01-01

327

World-making with extended gravity black holes for cosmic natural selection in the multiverse scenario  

E-print Network

Physics is facing contingency. Not only in facts but also in laws (the frontier becoming extremely narrow). Cosmic natural selection is a tantalizing idea to explain the apparently highly improbable structure of our Universe. In this brief note I will study the creation of Universes by black holes in -string inspired- higher order curvature gravity.

A. Barrau

2007-02-09

328

Population genetics of marine species: the interaction of natural selection and historically differentiated populations  

Microsoft Academic Search

High gene flow, particularly as mediated by larval dispersal, has usually been viewed as sufficient to limit geographic isolation as a major source of population differentiation among marine species. Despite the general observation of relatively little geographic variation among populations of high dispersal marine species many cases of divergence have been observed and natural selection has usually been invoked to

Thomas J. Hilbish

1996-01-01

329

The genomics of natural selection and adaptation: Christmas past, present and future(?)  

Microsoft Academic Search

Background: Genomic analyses are being applied to ‘non-model’ species. These complexes are now ‘models’ for applying genomic approaches to test evolutionary hypotheses. These approaches have revealed the genetic underpinnings of natural selection and adaptation.Aims: We wish to illustrate that the newest techniques in genomics would not be possible without older technological and methodological advances. We also point to the necessity

Michael L. Arnold; Evangeline S. Ballerini; Amanda N. Brothers; Jennafer A. P. Hamlin; Caitlin D. A. Ishibashi; Matthew P. Zuellig

2012-01-01

330

Instructional Design Consequences of an Analogy between Evolution by Natural Selection and Human Cognitive Architecture  

Microsoft Academic Search

Evolution by natural selection may becharacterized as a system in which a largestore of genetic information will persistindefinitely while it remains coordinated withits environment but will continuously producesmall random variations that are tested forenvironmental effectiveness. In anyenvironment, effective variations will persistwhile ineffective variations will disappear.Similarly, human cognitive architectureincludes a large store of information held inlong-term memory that coordinates our cognitiveactivities.

John Sweller

2004-01-01

331

Plant mortality and natural selection may increase biomass yield in switchgrass swards  

Technology Transfer Automated Retrieval System (TEKTRAN)

Switchgrass (Panicum virgatum L.) is an important candidate for bioenergy feedstock production, prompting significant efforts to increase the number of breeding programs and the output of those programs. The objective of this experiment was to determine the potential utility of natural selection for...

332

The Power of Natural Selection: A Guided Investigation of Three Case Studies  

ERIC Educational Resources Information Center

I describe a quantitative approach to three case studies in evolution that can be used to challenge college freshmen to explore the power of natural selection and ask questions that foster a deeper understanding of its operation and relevance. Hemochromatosis, the peppered moth, and hominid cranial capacity are investigated with a common algebraic…

Beachly, William

2010-01-01

333

Genetic drift or natural selection? Hybridization and asymmetric mitochondrial introgression in two Caribbean lizards  

E-print Network

Genetic drift or natural selection? Hybridization and asymmetric mitochondrial introgression in two, indicating no effect of hybridization on this marker. In contrast, the two species shared nine NKTR alleles University, Durham, NC, USA Keywords: Caribbean Sea; DNAH3; evolutionary diversification; hybridization

Rodríguez, Javier A.

334

The Future of Natural Selection Knowledge Measurement: A Reply to Anderson et al. (2010)  

ERIC Educational Resources Information Center

The development of rich, reliable, and robust measures of the composition, structure, and stability of student thinking about core scientific ideas (such as natural selection) remains a complex challenge facing science educators. In their recent article (Nehm & Schonfeld 2008), the authors explored the strengths, weaknesses, and insights provided…

Nehm, Ross H.; Schonfeld, Irvin Sam

2010-01-01

335

Natural selection drives patterns of lake-stream divergence in stickleback foraging morphology  

Microsoft Academic Search

To what extent are patterns of biological diversification determined by natural selection? We addressed this question by exploring divergence in foraging morphology of threespine stickleback fish inhabiting lake and stream habitats within eight independent watersheds. We found that lake fish generally displayed more developed gill structures and had more streamlined bodies than did stream fish. Diet analysis revealed that these

D. BERNER; D. C. ADAMS; A.-C. GRANDCHAMP; A. P. HENDRY

2008-01-01

336

Natural Selection for Nucleotide Usage at Synonymous and Nonsynonymous Sites in Influenza A Virus Genes  

Microsoft Academic Search

Influenza A virus is one of the best-studied viruses and a model organism for the study of molecular evolution; in particular, much research has focused on detecting natural selection on influenza virus proteins. Here, we study the dynamics of the synonymous and nonsynonymous nucleotide composition of influenza A virus genes. In several genes, the nucleotide frequencies at synonymous positions drift

Sergey Kryazhimskiy; Georgii A. Bazykin; Jonathan Dushoff

2008-01-01

337

Mutation pressure, natural selection, and the evolution of base composition in Drosophila  

Microsoft Academic Search

Genome sequencing in a number of taxa has revealed variation in nucleotide composition both among regions of the genome and among functional classes of sites in DNA. Mutational biases, biased gene conversion, and natural selection have been proposed as causes of this variation. Here, we review patterns of base composition in Drosophila DNA. Nucleotide composition in Drosophila melanogastervarys regionally, and

Hiroshi Akashi; Richard M. Kliman

1998-01-01

338

On Theoretical Models of Gene Expression Evolution with Random Genetic Drift and Natural Selection  

Microsoft Academic Search

BackgroundThe relative contributions of natural selection and random genetic drift are a major source of debate in the study of gene expression evolution, which is hypothesized to serve as a bridge from molecular to phenotypic evolution. It has been suggested that the conflict between views is caused by the lack of a definite model of the neutral hypothesis, which can

Osamu Ogasawara; Kousaku Okubo; Justin C. Fay

2009-01-01

339

Within and between-species DNA sequence variation and the ‘footprint’ of natural selection  

Microsoft Academic Search

Extensive DNA data emerging from genome-sequencing projects have revitalized interest in the mechanisms of molecular evolution. Although the contribution of natural selection at the molecular level has been debated for over 30years, the relevant data and appropriate statistical methods to address this issue have only begun to emerge. This paper will first present the predominant models of neutral, nearly neutral,

Hiroshi Akashi

1999-01-01

340

The Role of Natural Selection in Genetic Differentiation of Worldwide Populations of Drosophila ananassae  

Microsoft Academic Search

The main evolutionary forces leading to genetic differentiation between populations are generally considered to be natural selection, random genetic drift, and limited migration. However, little empirical evidence exists to help explain the extent, mechanism, and relative role of these forces. In this study, we make use of the differential migration behavior of genes located in regions of low and high

John F. Baines; Sylvain Mousset; Wolfgang Stephan

2004-01-01

341

Natural Selection and Shape Perception Manish Singh and Donald D. Hoffman  

E-print Network

Natural Selection and Shape Perception Manish Singh and Donald D. Hoffman Abstract We present-mail: manish@ruccs.rutgers.edu Donald D. Hoffman Department of Cognitive Science, University of California, Irvine, CA. e-mail: ddhoff@uci.edu 1 #12;2 Manish Singh and Donald D. Hoffman vival of the fitter

Singh, Manish

342

MHC studies in nonmodel vertebrates: what have we learned about natural selection in 15 years?  

Microsoft Academic Search

Elucidating how natural selection promotes local adaptation in interaction with migration, genetic drift and mutation is a central aim of evolutionary biology. While several conceptual and practical limitations are still restraining our ability to study these processes at the DNA level, genes of the major histocompatibility complex (MHC) offer several assets that make them unique candidates for this purpose. Yet,

L. B ERNATCHEZ; C. L ANDRY

2003-01-01

343

The effect of natural selection on the performance of maximum parsimony  

Microsoft Academic Search

BACKGROUND: Maximum parsimony is one of the most commonly used and extensively studied phylogeny reconstruction methods. While current evaluation methodologies such as computer simulations provide insight into how well maximum parsimony reconstructs phylogenies, they tell us little about how well maximum parsimony performs on taxa drawn from populations of organisms that evolved subject to natural selection in addition to the

Dehua Hang; Eric Torng; Charles Ofria; Thomas M Schmidt

2007-01-01

344

Darwin's Rehabilitation of Teleology Versus Williams' Replacement of Teleology by Natural Selection  

Microsoft Academic Search

Williams argued that Darwin replaced teleology by natural selection. This article argues that this idea is based on a misunderstanding of Darwin’s critique of the argument from design. Darwin did not replace teleology by evolutionary explanations but showed that we can understand teleology without referring to a Designer. He eliminated the concept of design and rehabilitated Aristotelian teleological explanations. The

Harry Smit

2011-01-01

345

Instructional Design Consequences of an Analogy between Evolution by Natural Selection and Human Cognitive Architecture  

ERIC Educational Resources Information Center

Evolution by natural selection may be characterized as a system in which a large store of genetic information will persist indefinitely while it remains coordinated with its environment but will continuously produce small random variations that are tested for environmental effectiveness. In any environment, effective variations will persist while…

Sweller, John

2004-01-01

346

The GIST Model for Selection and Modification of Scientific Research for the College Teaching Laboratory Based on Root Competition Investigations  

ERIC Educational Resources Information Center

The purpose of this study is to first develop an 8-week college teaching module based on root competition literature. The split-root technique is adapted for the teaching laboratory, and the Sugar Ann English pea (Pisum sativum var. Sugar Ann English) is selected as the species of interest prior to designing experiments, either original or…

Elliott, Shannon Snyder

2007-01-01

347

Analysis of environmental contamination resulting from catastrophic incidents: part 2. Building laboratory capability by selecting and developing analytical methodologies.  

PubMed

Catastrophic incidents can generate a large number of samples of analytically diverse types, including forensic, clinical, environmental, food, and others. Environmental samples include water, wastewater, soil, air, urban building and infrastructure materials, and surface residue. Such samples may arise not only from contamination from the incident but also from the multitude of activities surrounding the response to the incident, including decontamination. This document summarizes a range of activities to help build laboratory capability in preparation for sample analysis following a catastrophic incident, including selection and development of fit-for-purpose analytical methods for chemical, biological, and radiological contaminants. Fit-for-purpose methods are those which have been selected to meet project specific data quality objectives. For example, methods could be fit for screening contamination in the early phases of investigation of contamination incidents because they are rapid and easily implemented, but those same methods may not be fit for the purpose of remediating the environment to acceptable levels when a more sensitive method is required. While the exact data quality objectives defining fitness-for-purpose can vary with each incident, a governing principle of the method selection and development process for environmental remediation and recovery is based on achieving high throughput while maintaining high quality analytical results. This paper illustrates the result of applying this principle, in the form of a compendium of analytical methods for contaminants of interest. The compendium is based on experience with actual incidents, where appropriate and available. This paper also discusses efforts aimed at adaptation of existing methods to increase fitness-for-purpose and development of innovative methods when necessary. The contaminants of interest are primarily those potentially released through catastrophes resulting from malicious activity. However, the same techniques discussed could also have application to catastrophes resulting from other incidents, such as natural disasters or industrial accidents. Further, the high sample throughput enabled by the techniques discussed could be employed for conventional environmental studies and compliance monitoring, potentially decreasing costs and/or increasing the quantity of data available to decision-makers. PMID:24568927

Magnuson, Matthew; Campisano, Romy; Griggs, John; Fitz-James, Schatzi; Hall, Kathy; Mapp, Latisha; Mullins, Marissa; Nichols, Tonya; Shah, Sanjiv; Silvestri, Erin; Smith, Terry; Willison, Stuart; Ernst, Hiba

2014-11-01

348

Lifetime selection on heritable life-history traits in a natural population of red squirrels.  

PubMed

Despite their importance in evolutionary biology, heritability and the strength of natural selection have rarely been estimated in wild populations of iteroparous species or have usually been limited to one particular event during an organism's lifetime. Using an animal-model restricted maximum likelihood and phenotypic selection models, we estimated quantitative genetic parameters and the strength of lifetime selection on parturition date and litter size at birth in a natural population of North American red squirrels, Tamiasciurus hudsonicus. Litter size at birth and parturition date had low heritabilities (h2 = 0.15 and 0.16, respectively). We considered potential effects of temporal environmental covariances between phenotypes and fitness and of spatial environmental heterogeneity in estimates of selection. Selection favored early breeders and females that produced litter sizes close to the population average. Stabilizing selection on litter size at birth may occur because of a trade-off between number of offspring produced per litter and offspring survival or a trade-off between a female's fecundity and her future reproductive success and survival. PMID:14628929

Réale, D; Berteaux, D; McAdam, A G; Boutin, S

2003-10-01

349

Gene expression levels are a target of recent natural selection in the human genome.  

PubMed

Changes in gene expression may represent an important mode of human adaptation. However, to date, there are relatively few known examples in which selection has been shown to act directly on levels or patterns of gene expression. In order to test whether single nucleotide polymorphisms (SNPs) that affect gene expression in cis are frequently targets of positive natural selection in humans, we analyzed genome-wide SNP and expression data from cell lines associated with the International HapMap Project. Using a haplotype-based test for selection that was designed to detect incomplete selective sweeps, we found that SNPs showing signals of selection are more likely than random SNPs to be associated with gene expression levels in cis. This signal is significant in the Yoruba (which is the population that shows the strongest signals of selection overall) and shows a trend in the same direction in the other HapMap populations. Our results argue that selection on gene expression levels is an important type of human adaptation. Finally, our work provides an analytical framework for tackling a more general problem that will become increasingly important: namely, testing whether selection signals overlap significantly with SNPs that are associated with phenotypes of interest. PMID:19091723

Kudaravalli, Sridhar; Veyrieras, Jean-Baptiste; Stranger, Barbara E; Dermitzakis, Emmanouil T; Pritchard, Jonathan K

2009-03-01

350

Detecting the Genetic Signature of Natural Selection in Human Populations: Models, Methods, and Data  

PubMed Central

Patterns of DNA sequence variation in the genome contain a record of past selective events. The ability to collect increasingly large data sets of polymorphisms has allowed investigators to perform hypothesis-driven studies of candidate genes as well as genome-wide scans for signatures of adaptations. This genetic approach to the study of natural selection has identified many signals consistent with predictions from anthropological studies. Selective pressures related to variation in climate, diet, and pathogen exposure have left strong marks on patterns of human variation. Additional signals of adaptations are observed in genes involved in chemosensory perception and reproduction. Several ongoing projects aim to sequence the complete genome of 1000 individuals from different human populations. These large-scale projects will provide data for more complete genome scans of selection, but more focused studies aimed at testing specific hypotheses will continue to hold an important place in elucidating the history of adaptations in humans. PMID:20622977

Hancock, Angela M.; Rienzo, Anna Di

2010-01-01

351

Natural selection governs local, but not global, evolutionary gene coexpression networks in Caenorhabditis elegans  

PubMed Central

Background Large-scale evaluation of gene expression variation among Caenorhabditis elegans lines that have diverged from a common ancestor allows for the analysis of a novel class of biological networks – evolutionary gene coexpression networks. Comparative analysis of these evolutionary networks has the potential to uncover the effects of natural selection in shaping coexpression network topologies since C. elegans mutation accumulation (MA) lines evolve essentially free from the effects of natural selection, whereas natural isolate (NI) populations are subject to selective constraints. Results We compared evolutionary gene coexpression networks for C. elegans MA lines versus NI populations to evaluate the role that natural selection plays in shaping the evolution of network topologies. MA and NI evolutionary gene coexpression networks were found to have very similar global topological properties as measured by a number of network topological parameters. Observed MA and NI networks show node degree distributions and average values for node degree, clustering coefficient, path length, eccentricity and betweeness that are statistically indistinguishable from one another yet highly distinct from randomly simulated networks. On the other hand, at the local level the MA and NI coexpression networks are highly divergent; pairs of genes coexpressed in the MA versus NI lines are almost entirely different as are the connectivity and clustering properties of individual genes. Conclusion It appears that selective forces shape how local patterns of coexpression change over time but do not control the global topology of C. elegans evolutionary gene coexpression networks. These results have implications for the evolutionary significance of global network topologies, which are known to be conserved across disparate complex systems. PMID:19014554

Jordan, I King; Katz, Lee S; Denver, Dee R; Streelman, J Todd

2008-01-01

352

Cyclone Tolerance in New World Arecaceae: Biogeographic Variation and Abiotic Natural Selection  

PubMed Central

Background and Aims Consistent abiotic factors can affect directional selection; cyclones are abiotic phenomena with near-discrete geographic limits. The current study investigates selective pressure of cyclones on plants at the species level, testing for possible natural selection. Methods New World Arecaceae (palms) are used as a model system, as plants with monopodial, unbranched arborescent form are most directly affected by the selective pressure of wind load. Living specimens of known provenance grown at a common site were affected by the same cyclone. Data on percentage mortality were compiled and analysed in biogeographic and phylogenetic contexts. Key Results Palms of cyclone-prone provenance exhibited a much lower (one order of magnitude) range in cyclone tolerance, and significantly lower (P < 0·001) mean percentage mortality than collections from cyclone-free areas. Palms of cyclone-free provenance had much greater variation in tolerance, and significantly greater mean percentage mortality. A test for serial independence recovered no significant phylogenetic autocorrelation of percentage mortality. Conclusions Variation in cyclone tolerance in New World Arecaceae correlates with biogeography, and is not confounded with phylogeny. These results suggest natural selection of cyclone tolerance in cyclone-prone areas. PMID:18669575

Griffith, M. Patrick; Noblick, Larry R.; Dowe, John L.; Husby, Chad E.; Calonje, Michael A.

2008-01-01

353

Patterns of phenoloxidase activity in insecticide resistant and susceptible mosquitoes differ between laboratory-selected and wild-caught individuals  

PubMed Central

Background Insecticide resistance has the potential to alter vector immune competence and consequently affect the transmission of diseases. Methods Using both laboratory isogenic strains and field-caught Culex pipiens mosquitoes, we investigated the effects of insecticide resistance on an important component of the mosquito immune system: the phenoloxidase (PO) activity. As infection risk varies dramatically with the age and sex of mosquitoes, allocation to PO immunity was quantified across different stages of the mosquito life cycle. Results Our results were consistent in showing that larvae have a higher PO activity than adults, females have a higher PO activity than males, and PO activity declines with adult age. We obtained, however, a marked discrepancy between laboratory and field-collected mosquitoes on the effect of insecticide resistance on PO activity. In the laboratory selected strains we found evidence of strong interactions between insecticide resistance and the age and sex of mosquitoes. In particular, 7 and 14 day old esterase-resistant adult females and acetylcholine-esterase resistant males had significantly higher PO activities than their susceptible counterparts. No such effects were, however, apparent in field-caught mosquitoes. Conclusions Combined, the field and laboratory-based approaches employed in this study provide a powerful test of the effect of insecticide resistance on PO-mediated immunity. The use of laboratory-selected insecticide-resistant strains is still the most widely used method to investigate the pleiotropic effects of insecticide resistance. Our results suggest that the outcome of these laboratory-selected mosquitoes must be interpreted with caution and, whenever possible, compared with mosquitoes captured from the field. PMID:24499651

2013-01-01

354

Natural Gamma Emitters after a Selective Chemical Separation of a TENORM residue: Preliminary Results  

SciTech Connect

An analytical procedure was established in order to obtain selective fractions containing radium isotopes ({sup 228}Ra), thorium ({sup 232}Th), and rare earths from RETOTER (REsiduo de TOrio e TErras Raras), a solid residue rich in rare earth elements, thorium isotopes and small amount of natural uranium generated from the operation of a thorium pilot plant for purification and production of pure thorium nitrate at IPEN -CNEN/SP. The paper presents preliminary results of {sup 228}Ra, {sup 226}Ra, {sup 238}U, {sup 210}Pb, and {sup 40}K concentrations in the selective fractions and total residue determined by high-resolution gamma spectroscopy, considering radioactive equilibrium of the samples.

Alves de Freitas, Antonio; Abrao, Alcidio [Centro de Quimica e do Meio Ambiente (Brazil); Godoy dos Santos, Adir Janete; Pecequilo, Brigitte Roxana Soreanu [Centro de Metrologia das Radiacoes Instituto de Pesquisas Energeticas e Nucleares Av. Prof. Lineu Prestes, 2242-Cidade Universitaria-Zip Code 05508-000 Sao Paulo-SP (Brazil)

2008-08-07

355

Natural Gamma Emitters after a Selective Chemical Separation of a TENORM residue: Preliminary Results  

NASA Astrophysics Data System (ADS)

An analytical procedure was established in order to obtain selective fractions containing radium isotopes (228Ra), thorium (232Th), and rare earths from RETOTER (REsíduo de TÓrio e TErras Raras), a solid residue rich in rare earth elements, thorium isotopes and small amount of natural uranium generated from the operation of a thorium pilot plant for purification and production of pure thorium nitrate at IPEN -CNEN/SP. The paper presents preliminary results of 228Ra, 226Ra, 238U, 210Pb, and 40K concentrations in the selective fractions and total residue determined by high-resolution gamma spectroscopy, considering radioactive equilibrium of the samples.

de Freitas, Antonio Alves; dos Santos, Adir Janete Godoy; Pecequilo, Brigitte Roxana Soreanu; Abrão, Alcídio

2008-08-01

356

Material selection for wellhead equipment exposed to chlorinated and natural seawater  

SciTech Connect

Corrosion resistant alloys have been used in marine environments for their corrosion resistance. However, some of these materials are prone to localized corrosion, in particular crevice and pitting corrosion, in natural seawater. Injection water normally consists of de-oxygenated seawater, but, more recently either continuously or batch chlorinated and fully oxygenated seawater has been selected for this purpose because of their cost benefits. This investigation covers testing of corrosion resistant materials to aid in the selection of materials for wellhead equipment in an oxygenated and chlorinated seawater injection environment.

Olsen, S.; Nice, P.; Strandmyr, O. [Statoil, Stavanger (Norway); Maligas, M.; Vicic, J. [FMC Corp., Houston, TX (United States). Wellhead Equipment Div.

1996-08-01

357

Laboratory Constraints on the Stability of Petroleum at Elevated Temperatures: Implications for the Origin of Natural Gas  

SciTech Connect

Results of prior DOE supported research conducted at the Woods Hole Oceanographic Institution have demonstrated the participation of sedimentary minerals and water as reactants and catalysts in chemical transformations associated with the degradation of oil and the formation of low molecular weight organic compounds. The occurrence of such processes in natural environments can be difficult to recognize because the composition of organic alteration products may not be substantially different than those produced by thermal cracking. The goals of this study were the development of diagnostic tools based on hydrogen and carbon isotopes that can be used to identify geochemical processes responsible for the formation of thermogenic natural gas. In addition, our activities were expanded to include experimental investigation of CO2 reduction in aqueous systems at elevated temperature and pressures and an assessment of microbial activity in relatively low temperature (<70°C) natural gas reservoirs in southeastern Oklahoma. Specific objectives included: ? A laboratory investigation of geochemical processes that regulate the hydrogen isotope composition of low molecular weight hydrocarbons in natural gas at elevated temperatures and pressures. ? A laboratory investigation of factors that regulate the carbon isotope composition of organic acids in basinal brines. ? A laboratory assessment of the role of methanol during reduction of CO2 to CH4 under hydrothermal conditions. ? Characterization of microbial ecosystems in coproduced fluids from the Potato Hills gas field to assess the role of microbes in the generation of natural gas.

Seewald, Jeffrey, S.

2011-03-14

358

Statistical tests for natural selection on regulatory regions based on the strength of transcription factor binding sites  

Microsoft Academic Search

BACKGROUND: Although cis-regulatory changes play an important role in evolution, it remains difficult to establish the contribution of natural selection to regulatory differences between species. For protein coding regions, powerful tests of natural selection have been developed based on comparisons of synonymous and non-synonymous substitutions, and analogous tests for regulatory regions would be of great utility. RESULTS: Here, tests for

Alan M Moses

2009-01-01

359

Field and laboratory arsenic speciation methods and their application to natural-water analysis  

USGS Publications Warehouse

The toxic and carcinogenic properties of inorganic and organic arsenic species make their determination in natural water vitally important. Determination of individual inorganic and organic arsenic species is critical because the toxicology, mobility, and adsorptivity vary substantially. Several methods for the speciation of arsenic in groundwater, surface-water, and acid mine drainage sample matrices using field and laboratory techniques are presented. The methods provide quantitative determination of arsenite [As(III)], arsenate [As(V)], monomethylarsonate (MMA), dimethylarsinate (DMA), and roxarsone in 2-8min at detection limits of less than 1??g arsenic per liter (??g AsL-1). All the methods use anion exchange chromatography to separate the arsenic species and inductively coupled plasma-mass spectrometry as an arsenic-specific detector. Different methods were needed because some sample matrices did not have all arsenic species present or were incompatible with particular high-performance liquid chromatography (HPLC) mobile phases. The bias and variability of the methods were evaluated using total arsenic, As(III), As(V), DMA, and MMA results from more than 100 surface-water, groundwater, and acid mine drainage samples, and reference materials. Concentrations in test samples were as much as 13,000??g AsL-1 for As(III) and 3700??g AsL-1 for As(V). Methylated arsenic species were less than 100??g AsL-1 and were found only in certain surface-water samples, and roxarsone was not detected in any of the water samples tested. The distribution of inorganic arsenic species in the test samples ranged from 0% to 90% As(III). Laboratory-speciation method variability for As(III), As(V), MMA, and DMA in reagent water at 0.5??g AsL-1 was 8-13% (n=7). Field-speciation method variability for As(III) and As(V) at 1??g AsL-1 in reagent water was 3-4% (n=3). ?? 2003 Elsevier Ltd. All rights reserved.

Bednar, A.J.; Garbarino, J.R.; Burkhardt, M.R.; Ranville, J.F.; Wildeman, T.R.

2004-01-01

360

Coated-Wire Ion Selective Electrodes and Their Application to the Teaching Laboratory.  

ERIC Educational Resources Information Center

Describes the procedures for construction of a nitrate coated-wire ion selective electrode and suggests experiments for evaluation of electrode response and illustration of typical analytical applications of ion selective electrodes. (CS)

Martin, Charles R.; Freiser, Henry

1980-01-01

361

Human vs. Computer Diagnosis of Students’ Natural Selection Knowledge: Testing the Efficacy of Text Analytic Software  

Microsoft Academic Search

Our study examines the efficacy of Computer Assisted Scoring (CAS) of open-response text relative to expert human scoring\\u000a within the complex domain of evolutionary biology. Specifically, we explored whether CAS can diagnose the explanatory elements\\u000a (or Key Concepts) that comprise undergraduate students’ explanatory models of natural selection with equal fidelity as expert\\u000a human scorers in a sample of >1,000 essays.

Ross H. Nehm; Hendrik Haertig

2011-01-01

362

How Some Major Components of Religion Could Have Evolved by Natural Selection?  

Microsoft Academic Search

Religion is a broad concept that is difficult to define, as each definition has exceptions. As a result, it is difficult to\\u000a ask how religion as a whole could have evolved by natural selection\\u000a . An alternative is to divide religion into its components – behavior, beliefs, values, moods, and feelings. One can then\\u000a ask the same question of these

Jay R. Feierman

363

Evolutionarily stable sets in the single-locus frequency-dependent model of natural selection  

Microsoft Academic Search

Recent developments in the static theory of evolutionarily stable sets (ESSets) are applied to the single-locus frequency-dependent model of natural selection. Particular emphasis is paid to the ESSet properties of the preimage of an ESS (or ESSet) under the genotype-phenotype map. When an ESS is realized in genetic equilibrium with redundancy in a diploid sexual population, the basic problem in

Ross Cressman; József Garay; Zoltán Varga

2003-01-01

364

Natural selection among Eurasians at genomic regions associated with HIV1 control  

Microsoft Academic Search

Background  HIV susceptibility and pathogenicity exhibit both interindividual and intergroup variability. The etiology of intergroup variability\\u000a is still poorly understood, and could be partly linked to genetic differences among racial\\/ethnic groups. These genetic differences\\u000a may be traceable to different regimes of natural selection in the 60,000 years since the human radiation out of Africa. Here,\\u000a we examine population differentiation and haplotype

Yann C Klimentidis; Brahim Aissani; Mark D Shriver; David B Allison; Sadeep Shrestha

2011-01-01

365

Natural selection and the molecular basis of electrophoretic variation at the coagulation F13B locus  

Microsoft Academic Search

Electrophoretic analysis of protein variation at the coagulation F13B locus has previously revealed three alleles, with alleles 1, 2, and 3 each being at high frequency in European, African, and Asian populations, respectively. To determine if this unusual pattern of interpopulation differentiation reflects local natural selection or neutral genetic drift, we re-sequenced 4.6 kb of the gene, encompassing all exons,

Anthony W Ryan; David A Hughes; Kun Tang; Dermot P Kelleher; Thomas Ryan; Ross McManus; Mark Stoneking

2009-01-01

366

Mutation pressure, natural selection, and the evolution of base composition in Drosophila  

Microsoft Academic Search

Genome sequencing in a number of taxa has revealed variation in nucleotide composition both among regions of the genome and\\u000a among functional classes of sites in DNA. Mutational biases, biased gene conversion, and natural selection have been proposed\\u000a as causes of this variation. Here, we review patterns of base composition in Drosophila DNA. Nucleotide composition in Drosophila\\u000a melanogaster varys regionally,

Hiroshi Akashi; Richard M. Kliman; Adam Eyre-Walker

1998-01-01

367

Separating Effects of Gene Flow and Natural Selection along an Environmental Gradient  

Microsoft Academic Search

Genetic differentiation along environmental clines is often observed as a result of interplay between gene flow and natural\\u000a selection. In order to understand the relative roles of these processes in shaping this differentiation, we designed a study\\u000a in which we used two approaches that have not previously been combined, the Q\\u000a ST–F\\u000a ST comparison and crossbreeding. We examined (1) interpopulation

Sergei Volis; Yong-Hong Zhang

2010-01-01

368

Temperature oscillations may shorten male lifespan via natural selection in utero  

Microsoft Academic Search

Much literature argues that natural selection has conserved mechanisms that spontaneously abort fetuses, particularly males,\\u000a least likely to survive in prevailing environmental conditions including cold ambient temperature. These reports imply the\\u000a hypothesis that males in gestation during relatively warm periods who confront relatively cold climates in early life live,\\u000a on average, shorter lives than other males. We estimate the effect

Ralph A. Catalano; Tim A. Bruckner; Kirk R. Smith; Katherine B. Saxton

2012-01-01

369

Laboratory Evaluation of Ion-Selective Electrodes for Simultaneous Analysis of Macronutrients in Hydroponic Solution  

Technology Transfer Automated Retrieval System (TEKTRAN)

Automated sensing of macronutrients in hydroponic solution would allow more efficient management of nutrients for crop growth in closed hydroponic systems. Ion-selective microelectrode technology requires an ion-selective membrane or a solid metal material that responds selectively to one analyte in...

370

Beyond the ecological: biological invasions alter natural selection on a native plant species.  

PubMed

Biological invasions can have strong ecological effects on native communities by altering ecosystem functions, species interactions, and community composition. Even though these ecological effects frequently impact the population dynamics and fitness of native species, the evolutionary consequences of biological invasions have received relatively little attention. Here, I show that invasions impose novel selective pressures on a native plant species. By experimentally manipulating community composition, I found that the exotic plant Medicago polymorpha and the exotic herbivore Hypera brunneipennis alter the strength and, in some instances, the direction of natural selection on the competitive ability and anti-herbivore defenses of the native plant Lotus wrangelianus. Furthermore, the community composition of exotics influenced which traits were favored. For example, high densities of the exotic herbivore Hypera selected for increased resistance to herbivores in the native Lotus; however, when Medicago also was present, selection on this defense was eliminated. In contrast, selection on tolerance, another plant defense trait, was highest when both Hypera and Medicago were present at high densities. Thus, multiple exotic species may interact to influence the evolutionary trajectories of native plant populations, and patterns of selection may change as additional exotic species invade the community. PMID:18481527

Lau, Jennifer A

2008-04-01

371

QC Validator 2.0: a computer program for automatic selection of statistical QC procedures for applications in healthcare laboratories.  

PubMed

A computer program has been developed to help healthcare laboratories select statistical control rules and numbers of control measurements that will assure the quality required by clinical decision interval criteria or analytical total error criteria. The program (QC Validator 2.0 (QC Validator and OPSpecs are registered trademarks of Westgard Quality Corporation, which has applied for a patent for this automatic QC selection process. Windows is a registered trademark of Microsoft Corporation)) runs on IBM compatible personal computers operating under Windows. The user enters information about the method imprecision, inaccuracy, and expected frequency of errors, defines the quality required in terms of a medically important change (clinical decision interval) or an analytical allowable total error, then initiates automatic selection by indicating the number of control materials that are to be analyzed (1, 2, or 3). The program returns with a chart of operating specifications (OPSpecs chart) that displays the selected control rules and numbers of control measurements. The automatic QC selection process is based on user editable criteria for the types of control rules that can be implemented by the laboratory, total numbers of control measurements that are practical, maximum levels of false rejections that can be tolerated and minimum levels of error detection that are acceptable for detection of medically important systematic or random errors. PMID:9230452

Westgard, J O; Stein, B; Westgard, S A; Kennedy, R

1997-07-01

372

Tropolones As Lead-Like Natural Products: The Development of Potent and Selective Histone Deacetylase Inhibitors  

PubMed Central

Natural products have long been recognized as a rich source of potent therapeutics but further development is often limited by high structural complexity and high molecular weight. In contrast, at the core of the thujaplicins is a lead-like tropolone scaffold characterized by relatively low molecular weight, ample sites for diversification, and metal-binding functionality poised for targeting a range of metalloenzyme drug targets. Here, we describe the development of this underutilized scaffold for the discovery of tropolone derivatives that function as isozyme-selective inhibitors of the validated anticancer drug target, histone deacetylase (HDAC). Several monosubstituted tropolones display remarkable levels of selectivity for HDAC2 and potently inhibit the growth of T-cell lymphocyte cell lines. The tropolones represent a new chemotype of isozyme-selective HDAC inhibitors. PMID:24900743

2013-01-01

373

Does natural selection organize ecosystems for the maintenance of high productivity and diversity?  

PubMed Central

Three types of evidence suggest that natural ecosystems are organized for high productivity and diversity: (i) changes not previously experienced by a natural ecosystem, such as novel human disturbances, tend to diminish its productivity and/or diversity, just as 'random' changes in a machine designed for a function usually impair its execution of that function; (ii) humans strive to recreate properties of natural ecosystems to enhance productivity of artificial ones, as farmers try to recreate properties of natural soils in their fields; and (iii) productivity and diversity have increased during the Earth's history as a whole, and after every major biotic crisis. Natural selection results in ecosystems organized to maintain high productivity of organic matter and diversity of species, just as competition among individuals in Adam Smith's ideal economy favours high production of wealth and diversity of occupations. In nature, poorly exploited energy attracts more efficient users. This circumstance favours the opening of new ways of life and more efficient recycling of resources, and eliminates most productivity-reducing 'ecological monopolies'. Ecological dominants tend to be replaced by successors with higher metabolism, which respond to more stimuli and engage in more varied interactions. Finally, increasingly efficient predators and herbivores favour faster turnover of resources. PMID:12079531

Leigh, Egbert Giles; Vermeij, Geerat Jacobus

2002-01-01

374

Footprints of divergent selection in natural populations of Castanopsis fargesii (Fagaceae).  

PubMed

Given predicted rapid climate change, an understanding of how environmental factors affect genetic diversity in natural populations is important. Future selection pressures are inherently unpredictable, so forest management policies should maintain both overall diversity and identify genetic markers associated with the environmental factors expected to change most rapidly, like temperature and rainfall. In this study, we genotyped 648 individuals in 28 populations of Castanopsis fargesii (Fagaceae) using 32 expressed sequence tag (EST)-derived microsatellite markers. After removing six loci that departed from Hardy-Weinberg equilibrium, we measured genetic variation, population structure and identified candidate loci putatively under selection by temperature and precipitation. We found that C. fargesii populations possessed high genetic diversity and moderate differentiation among them, indicating predominant outcrossing and few restrictions to gene flow. These patterns reduce the possible impact of stochastic effects or the influence of genetic isolation. Clear footprints of divergent selection at four loci were discovered. Frequencies of five alleles at these loci were strongly correlated with environmental factors, particularly extremes in precipitation. These alleles varied from being near fixation at one end of the gradient to being completely absent at the other. Our study species is an important forest tree in the subtropical regions of China and could have a major role in future management and reforestation plans. Our results demonstrate that the gene flow is widespread and abundant in natural populations, maintaining high diversity, while diversifying selection is acting on specific genomic regions. PMID:24984608

Li, C; Sun, Y; Huang, H W; Cannon, C H

2014-12-01

375

Life history QTLs and natural selection on flowering time in Boechera stricta, a perennial relative of Arabidopsis  

PubMed Central

Plants must precisely time flowering to capitalize on favorable conditions. Although we know a great deal about the genetic basis of flowering phenology in model species under controlled conditions, the genetic architecture of this ecologically-important trait is poorly understood in non-model organisms. Here, we evaluated the transition from vegetative growth to flowering in Boechera stricta, a perennial relative of Arabidopsis thaliana. We examined flowering time QTLs using 7,920 recombinant inbred individuals, across seven lab and field environments differing in vernalization, temperature, and photoperiod. Genetic and environmental factors strongly influenced the transition to reproduction. We found directional selection for earlier flowering in the field. In the growth chamber experiment, longer winters accelerated flowering, whereas elevated ambient temperatures delayed flowering. Our analyses identified one large effect QTL (nFT), which influenced flowering time in both experiments and the probability of flowering in the field. In Montana, homozygotes for the native allele at nFT showed a selective advantage of 6.6%. Nevertheless, we found relatively low correlations between flowering times in the field and the growth chambers. Additionally, we detected flowering-related QTLs in the field which were absent across the full range of laboratory conditions, thus emphasizing the need to conduct experiments in natural environments. PMID:21083662

Anderson, Jill T.; Lee, Cheng-Ruei; Mitchell-Olds, Thomas

2011-01-01

376

Long-term selective retention of natural Cs and Rb by highly weathered coastal plain soils.  

PubMed

Naturally occurring Cs and Rb are distinctly more abundant relative to K in the highly weathered upland soils of the Savannah River Site, South Carolina, than in average rock of Earth's upper continental crust (UCC), by factors of 10 and 4, respectively. Naturally occurring Cs has been selectively retained during soil evolution, and Rb to a lesser extent, while K has been leached away. In acid extracts of the soils, the Cs/K ratio is about 50 times and the Rb/K ratio about 15 times the corresponding ratios for the UCC, indicating that relatively large amounts of natural Cs and Rb have been sequestered in soil microenvironments that are highly selective for these elements relative to K. Cation exchange favoring Cs and Rb ions, and subsequent fixation of the ions, at sites in interlayer wedge zones within hydroxy-interlayered vermiculite particles may account for the observations. The amounts of stable Cs retained and the inferred duration of the soil evolution, many thousands of years, provide new insights regarding long-term stewardship of radiocesium in waste repositories and contaminated environments. Study of natural Cs in soil adds a long-term perspective on Cs transport in soils not available from studies of radiocesium. PMID:22324361

Wampler, J M; Krogstad, Eirik J; Elliott, W Crawford; Kahn, Bernd; Kaplan, Daniel I

2012-04-01

377

Phenotypic selection on leaf water use efficiency and related ecophysiological traits for natural populations of desert sunflowers  

Microsoft Academic Search

Plant water-use efficiency (WUE) is expected to affect plant fitness and thus be under natural selection in arid habitats.\\u000a Although many natural population studies have assessed plant WUE, only a few related WUE to fitness. The further determination\\u000a of whether selection on WUE is direct or indirect through functionally related traits has yielded no consistent results. For\\u000a natural populations of

Lisa A. Donovan; Susan A. Dudley; David M. Rosenthal; Fulco Ludwig

2007-01-01

378

Genetic Drift and Natural Selection in an Isolated Zapotec-Speaking Community in the Valley of Oaxaca, Southern Mexico  

Microsoft Academic Search

Genetic drift and natural selection were analyzed in a genetically isolated Zapotec-speaking community in the Valley of Oaxaca, southern Mexico. Moderately intense genetic drift and selection potentials were found. Potential for drift was related to (1) the small effective size of the population, and (2) the exceptionally low number of migrants into the population. Potential for selection was due to

Bertis B. Little; Robert M. Malina

1989-01-01

379

Unified synthesis of caged Garcinia natural products based on a site-selective Claisen DielsAlder  

E-print Network

Unified synthesis of caged Garcinia natural products based on a site-selective Claisen Diels natural prod- ucts has been designed and implemented. Central to the strategy is a tandem Claisen Diels natural products with high pharmaceutical potential (3). For example, gamboge, the com- mercially

Theodorakis, Emmanuel

380

Learning natural scene categories by selective multi-scale feature extraction Alessandro Perina a,*, Marco Cristani b,1  

E-print Network

Learning natural scene categories by selective multi-scale feature extraction Alessandro Perina a t Natural scene categorization from images represents a very useful task for automatic image analysis sys disregarding whether they derive properly from the natural scene to be classified or from foreground objects

Cristani, Marco

381

Effects of Heterogeneous Adsorption Affinity on Natural Organic Matter (NOM) Transport in Laboratory Sand Columns  

NASA Astrophysics Data System (ADS)

Transport of reactive sorbing solutes through porous media is commonly quantified by implementing an effective retardation coefficient in the advection-dispersion equation (ADE), which describes dispersion in accordance with Fick's law. However, anomalous (non-Fickian) transport behavior can be observed in systems with heterogeneous retardation coefficients (Dentz & Castro, 2009). In such systems, the ADE is unable to reproduce the non-Fickian nature of plume shapes and breakthrough curves, motivating the development and application of alternative solute transport theories, such as the continuous time random walk (CTRW) or multi-rate mass transfer (MRMT). Heterogeneity in retardation coefficients in practice arises from variability in the geochemical properties controlling sorption-desorption kinetics between the solute and mineral surfaces. These distributions have been described in the context of heterogeneity of the porous medium, but to date little attention has been given to the potential role of a geochemically heterogeneous solute. In this work, we consider a system in which anomalous transport arises during the passage of natural organic matter (NOM), a polydisperse mixture of compounds derived from the breakdown of plants and microorganisms in the environment, through homogeneous laboratory sand columns. NOM solutions were passed through columns containing either hematite, corundum, or a naturally-coated quartz sand at a variety of pH and ionic strength conditions. Influent and effluent NOM concentration was measured as UV absorbance at 254 nm. The resulting breakthrough curves are non-Fickian, displaying power-law tailing at late times. Such curves cannot be predicted by the ADE model. Reactivity of NOM components is known to be related to their molecular weight (MW), which tends to be log-normally distributed in aquatic NOM isolates (Cabaniss et al., 2000). Low-MW compounds are more water-soluble, have a higher diffusion coefficient, and due to their smaller structure, are able to enter nanopores which exclude macromolecules. Conversely, high-MW components are hydrophobic, less mobile, and have a greater affinity for metal binding than their smaller counterparts. By analyzing the transport of different NOM components in the effluent solution over time we see that there is a clear heterogeneity in the retardation of the different NOM components. Using the approaches of Dentz & Castro (2009) and Dentz & Bolster (2011) we can show that the effective upscaled transport can be modeled as a CTRW. To this end we demonstrate that the CTRW and MRMT models (which can be shown to be intricately related) can indeed faithfully capture the observed behavior. From a practical perspective, our experiments demonstrate increased mobility of low-MW fractions of NOM relative to high-MW fractions, which - given the ability of NOM to bind to organic compounds, metals, and radionuclides - could have important implications for contaminant transport in groundwater systems.

McInnis, D. P.; Bolster, D.; Maurice, P. A.

2012-12-01

382

ENVIRONMENTAL PATHWAYS OF SELECTED CHEMICALS IN FRESHWATER SYSTEMS. PART II. LABORATORY STUDIES  

EPA Science Inventory

Environmental exposure assessment models and laboratory procedures for predicting the pathways of potentially harmful chemicals in freshwater environments were described in Part I of this report (PB-274 548). Procedures were developed for measuring the rates of volatilization, ph...

383

75 FR 53277 - Notice of Intent To Terminate Selected National Voluntary Laboratory Accreditation Program (NVLAP...  

Federal Register 2010, 2011, 2012, 2013, 2014

...building seals and sealants, plastics, plumbing, roofing, and mattresses. DATES: The Commercial Products Testing Laboratory Accreditation...building seals and sealants, plastics, plumbing, roofing, and mattresses. The purpose of this program is to supply unbiased...

2010-08-31

384

Simulating intracrater ash recycling during mid-intensity explosive activity: high temperature laboratory experiments on natural basaltic ash  

NASA Astrophysics Data System (ADS)

Direct observations of mid-intensity eruptions, in which a huge amount of ash is generated, indicate that ash recycling is quite common. The recognition of juvenile vs. recycled fragments is not straightforward, and no unequivocal, widely accepted criteria exist to support this. The presence of recycled glassy fragments can hide primary magmatic information, introducing bias in the interpretations of the ongoing magmatic and volcanic activity. High temperature experiments were performed at atmospheric pressure on natural samples to investigate the effects of reheating on morphology, texture and composition of volcanic ash. Experiments simulate the transformation of juvenile glassy fragments that, falling into the crater or in the upper part of the conduit, are recycled by following explosions. Textural and compositional modifications obtained in laboratory are compared with similar features observed in natural samples in order to identify some main general criteria to be used for the discrimination of recycled material. Experiments were carried out on tephra produced during Strombolian activity, fire fountains and continuous ash emission at Etna, Stromboli and Vesuvius. Coarse glassy clasts were crushed in a nylon mortar in order to create an artificial ash, and then sieved to select the size interval of 1-0.71 mm. Ash shards were put in a sealed or open quartz tube, in order to prevent or to reproduce effects of air oxidation. The tube was suspended in a HT furnace at INGV-Pisa and kept at different temperatures (up to to 1110°C) for increasing time (0.5-12 hours). Preliminary experiments were also performed under gas flux conditions. Optical and electron microscope observations indicate that high temperature and exposure to the air induce large modifications on clast surface, ranging from change in color, to incipient plastic deformation till complete sintering. Significant change in color of clasts is strictly related to the presence of air, irrespective of temperature while sintering is favored by the high temperature and low fO2. Re-heating promotes nucleation and growth of crystals in the groundmass and associated change of glass composition, sometimes accompanied by growth and coalescence of vesicles in the size of 10-50 µm and cracking of the external surface.

D'Oriano, Claudia; Pompilio, Massimo; Bertagnini, Antonella; Cioni, Raffaello; Pichavant, Michel

2010-05-01

385

Natural Image Coding in V1: How Much Use Is Orientation Selectivity?  

PubMed Central

Orientation selectivity is the most striking feature of simple cell coding in V1 that has been shown to emerge from the reduction of higher-order correlations in natural images in a large variety of statistical image models. The most parsimonious one among these models is linear Independent Component Analysis (ICA), whereas second-order decorrelation transformations such as Principal Component Analysis (PCA) do not yield oriented filters. Because of this finding, it has been suggested that the emergence of orientation selectivity may be explained by higher-order redundancy reduction. To assess the tenability of this hypothesis, it is an important empirical question how much more redundancy can be removed with ICA in comparison to PCA or other second-order decorrelation methods. Although some previous studies have concluded that the amount of higher-order correlation in natural images is generally insignificant, other studies reported an extra gain for ICA of more than 100%. A consistent conclusion about the role of higher-order correlations in natural images can be reached only by the development of reliable quantitative evaluation methods. Here, we present a very careful and comprehensive analysis using three evaluation criteria related to redundancy reduction: In addition to the multi-information and the average log-loss, we compute complete rate–distortion curves for ICA in comparison with PCA. Without exception, we find that the advantage of the ICA filters is small. At the same time, we show that a simple spherically symmetric distribution with only two parameters can fit the data significantly better than the probabilistic model underlying ICA. This finding suggests that, although the amount of higher-order correlation in natural images can in fact be significant, the feature of orientation selectivity does not yield a large contribution to redundancy reduction within the linear filter bank models of V1 simple cells. PMID:19343216

Bethge, Matthias

2009-01-01

386

Bateman in nature: predation on offspring reduces the potential for sexual selection.  

PubMed

Sexual selection is driven by competition for mates, and the advantage of a competitor is determined by the number of offspring it produces. Early experiments by Angus Bateman characterized this interaction, and the quantitative relationship between a male's number of mates and number of offspring is known as the Bateman slope. Sexual dimorphism, one of the most obvious results of sexual selection, largely requires a positive Bateman relationship, and the slope provides an estimate of the potential for sexual selection. However, natural selection from the environment can also influence male success, as can random effects, and some have argued for inclusion of the latter in calculations of mate success. Data from pronghorn (Antilocapra americana) reveal the presence of a positive Bateman slope in each year of a 10-year study. We found no evidence that random effects skewed male mating success; however, substantial yearly variation in the Bateman slope due to predation on fawns was evident. These results support the validity of the Bateman relationship, yet they also demonstrate that environmental or extrinsic influences can limit the potential for sexual selection. PMID:23139332

Byers, John; Dunn, Stacey

2012-11-01

387

Capturing Naturally Occurring Superior Performance in the Laboratory: Translational Research on Expert Performance  

ERIC Educational Resources Information Center

One of the central challenges to studying highly skilled performance in the laboratory is methodological. It is necessary to develop standardized methods that allow investigators to make experts repeatedly reproduce their superior performance in the laboratory. The recent increase in demand for translational research has raised related issues of…

Ericsson, K. Anders; Williams, A. Mark

2007-01-01

388

Can natural phenotypic variances be estimated reliably under homogeneous laboratory conditions?  

E-print Network

and four size traits of neonates from eggs incubated in the laboratory and those left in situ. Mean size turtles (Chelydra serpentina) to a split-family design to evaluate the variability in incubation time measurements were similar between the laboratory and the field, but incubation time was systematically longer

Janzen, Fredric

389

Can natural phenotypic variances be estimated reliably under homogeneous laboratory conditions?  

PubMed

The phenotypic variance is assumed to be greater in a more heterogeneous environment. The validity of this assumption is important for microevolutionists to extrapolate results from the laboratory to field environments. We subjected clutches of eggs from common snapping turtles (Chelydra serpentina) to a split-family design to evaluate the variability in incubation time and four size traits of neonates from eggs incubated in the laboratory and those left in situ. Mean size measurements were similar between the laboratory and the field, but incubation time was systematically longer in the field. We found no tendency among clutches for hatchlings resulting from eggs incubated in laboratory or field environments to demonstrate greater variability. Also contrary to expectation, clutches that experienced greater thermal variation in the field did not exhibit greater variation in phenotypic traits. Consequently, extrapolating results from the laboratory to the field may not always be problematic for microevolutionary analyses. PMID:17584235

St Juliana, J R; Janzen, F J

2007-07-01

390

Natural Product Total Synthesis in the Organic Laboratory: Total Synthesis of Caffeic Acid Phenethyl Ester (CAPE), a Potent 5-Lipoxygenase Inhibitor from Honeybee Hives  

ERIC Educational Resources Information Center

Natural products play a critical role in modern organic synthesis and learning synthetic techniques is an important component of the organic laboratory experience. In addition to traditional one-step organic synthesis laboratories, a multistep natural product synthesis is an interesting experiment to challenge students. The proposed three-step…

Touaibia, Mohamed; Guay, Michel

2011-01-01

391

Development of resistance to spinosad in oriental fruit fly (Diptera: Tephritidae) in laboratory selection and cross-resistance.  

PubMed

In this study, we assessed the potential for the development of resistance to the insecticide spinosad in a laboratory colony of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). Resistance was selected by using topical applications of spinosad. After eight generations of selection, the LD50 of the selected line was 408 times greater compared with that of the untreated parental colony. This spinosad-resistant line did not exhibit cross-resistance to 10 other insecticides tested, including six organophosphates (naled, trichlorfon, fenitrothion. fenthion, formothion, and malathion) one carbamate (methomyl), and three pyrethroids (cyfluthrin, cypermethrin, and fenvalerate). However, using lines previously selected for resistance to these same insecticides, two of the 10 lines tested (naled- and malathion-resistant) did show some cross-resistance to spinosad. Also, oriental fruit flies from different field collections where naled and malathion have been used for control purposes displayed some resistance to spinosad. In addition, the effects of direct ingestion of spinosad through dietary supplementation also were tested. Overall, the laboratory resistance and cross-resistance data developed in this study provide new information that will be useful for managing the development of resistance when spinosad is used to control B. dorsalis in the field. PMID:16813333

Hsu, Ju-Chun; Feng, Hai-Tung

2006-06-01

392

The Himalayas of Nepal, a natural laboratory for the search and measurement of CO2 discharge  

NASA Astrophysics Data System (ADS)

Large CO2 flux has been found in the Trisuli Valley, North of Kathmandu, Central Nepal, in 2005. This leakage zone is located in the vicinity of the Syabru-Bensi hot springs, and is characterized by an average flux of CO2 of 6500±1100 g m-2 day-1 over an area of 15 m × 15 m (Perrier et al., Earth and Planetary Science Letters, 2009). The site is also located close to the Main Central Thrust Zone (MCT Zone), one of the large Himalayan thrust, connected at depth to the Main Himalayan Thrust, the main thrust currently accommodating the India-Tibet collision (Bollinger et al., Journal of Geophysical Research, 2004). Isotopic carbon ratios (?13C) indicate that this CO2 may come from metamorphic reactions at about 15 km of depth (Becker et al., Earth and Planetary Science Letters, 2008; Evans et al., Geochemistry Geophysics Geosystems, 2008). Actually, this zone was originally found because of the large ?13C found in the water of the hot springs suggesting degassing (Evans et al., Geochemistry Geophysics Geosystems, 2008). In 2007, another zone of CO2 discharge was discovered 250 m away from the main Syabru-Bensi hot springs. This new zone, located next to the road and easy to access all over the year, was intensely studied, from the end of 2007 to the beginning of 2009. In this zone, an average value of CO2 flux of 1700±300 g m-2 d-1 was obtained over an area of about 40 m × 10 m. Using CO2 flux data from repeated measurements, similar flux values were observed during the dry winter season and the wet summer period (monsoon) (Girault et al., Journal of Environmental Radioactivity, 2009). Thus, in addition to fundamental issues related to global CO2 balance in orogenic belts and tectonically active zones, these small scale (100-meter) CO2 discharge sites emerge as a potentially useful laboratory for detailed methodological studies of diffusive and advective gas transport. Recently, the search for further gas discharge zones has been carried out using various clues: the presence of a hot spring with high ?13C, of H2S smell, of hot spots in thermal images, of a geological contact, of self-potential anomalies (Byrdina et al., Journal of Geophysical Research, 2009) or of large radon-222 flux. Preliminary results about the failures or successes of the various methods will be given in the Trisuli and Langtang valleys (Central Nepal), in the Kali Gandaki valley (Western Nepal) and in the Thuli Bheri valley (Lower Dolpo, Far Western Nepal). These various sites also offer an opportunity to test the optimal estimation of total CO2 flux, using the least amount of experimental measurements. Preliminary results complemented by simulations will also be given on the total CO2 flux. In parallel, monitoring methods are being studied in the Syabru-Bensi pilot site. First, CO2 flux has been studied as a function of time using repeated measurements. Furthermore, the high radon content of the geological CO2 allows cost-effective monitoring using BARASOL probes. More than two years of data are already available and give hints on the use of radon to follow CO2 discharge as a function of time. These first results show how experimental studies carried out in natural discharge zones provide a rich laboratory to test the methodological approaches useful for CO2 leakage and monitoring.

Girault, Frédéric; Koirala, Bharat P.; Bhattarai, Mukunda; Rajaure, Sudhir; Richon, Patrick; Perrier, Frédéric

2010-05-01

393

Langutils: A Natural Language Toolkit for Common Lisp MIT Media Laboratory  

E-print Network

, Natural Language Processing (NLP) has emerged as an important capability in many applications and areas. INTRODUCTION Natural Language Processing is becoming an important capability for many modern applications. From to its user. Major forms of natural language processing in use today include: - Dialog or speech systems

394

An Easily Constructed Salicylate-Ion-Selective Electrode for Use in the Instructional Laboratory.  

ERIC Educational Resources Information Center

Describes an electrode, selective for the salicylate ion, that can be prepared and used by undergraduate students. Discusses the preparation of the electrode, typical response characteristics obtained, and results of a limited study using the electrode to estimate the selectivity coefficient for an interfering ion and to determine the amount of…

Creager, Stephen E.; And Others

1995-01-01

395

MDH-polymorphism in Drosophila subobscura : I. Selection and hitch-hiking in laboratory populations  

Microsoft Academic Search

The interrelation of genic polymorphism at the Malate dehydrogenase (Mdh)-locus and chromosomal polymorphism for superimposed gene arrangements was studied in 5 experimental populations of Drosophila subobscura. It could be shown that chromosomal polymorphism is maintained by balancing selection in favour of the heterozygotes. In contrast, selection at the Mdh-locus itself seems to be of minor importance. The changes of frequency

W. Pinsker

1981-01-01

396

A simple method for estimating the strength of natural selection on overlapping genes.  

PubMed

Overlapping genes, where one DNA sequence codes for two proteins with different reading frames, are not uncommon in viruses and cellular organisms. Estimating the direction and strength of natural selection acting on overlapping genes is important for understanding their functionality, origin, evolution, maintenance, and potential interaction. However, the standard methods for estimating synonymous (dS) and nonsynonymous (dN) nucleotide substitution rates are inapplicable here because a nucleotide change can be simultaneously synonymous and nonsynonymous when both reading frames involved are considered. We have developed a simple method that can estimate dN/dS and test for the action of natural selection in each relevant reading frame of the overlapping genes. Our method is an extension of the modified Nei-Gojobori method previously developed for nonoverlapping genes. We confirmed the reliability of our method using extensive computer simulation. Applying this method, we studied the longest human sense-antisense overlapping gene pair, LRRC8E and ENSG00000214248. Although LRRC8E (leucine-rich repeat containing eight family, member E) is known to regulate cell size, the function of ENSG00000214248 is unknown. Our analysis revealed purifying selection on ENSG00000214248 and suggested that it originated in the common ancestor of bony vertebrates. PMID:25552532

Wei, Xinzhu; Zhang, Jianzhi

2014-01-01

397

Evidence for selection by male mating success in natural populations of Drosophila pseudoobscura.  

PubMed Central

Gene arrangement frequencies were determined at two stages in the life history of Drosophila pseudoobscura taken from nature. Three populations in the central highlands of Mexico were each sampled twice during 1976. Gene arrangement frequencies were measured in adult males and in larvae that were the offspring of females collected at the same time. The adult males were in all likelihood a representative sample of those who fathered the larvae produced by the wild females. Differences in gene arrangement frequency between these two life stages should indicate the operation of natural selection. One-third of our comparisons of common gene arrangement frequencies in males and in larvae from the next generation were statistically significant, as were one-third of our comparisons of total frequency arrays in the two life stages. We consider the components of selection that could produce such frequency changes and reason that male mating success must be the major one. Gene arrangement frequencies in the Mexican populations fluctuate within wide bounds. Selection must act to retain the polymorphism in the face of this flux in gene arrangement frequencies, and we suggest that male mating success plays an important role. PMID:286338

Anderson, W W; Levine, L; Olvera, O; Powell, J R; de la Rosa, M E; Salceda, V M; Gaso, M I; Guzmán, J

1979-01-01

398

A Simple Method for Estimating the Strength of Natural Selection on Overlapping Genes  

PubMed Central

Overlapping genes, where one DNA sequence codes for two proteins with different reading frames, are not uncommon in viruses and cellular organisms. Estimating the direction and strength of natural selection acting on overlapping genes is important for understanding their functionality, origin, evolution, maintenance, and potential interaction. However, the standard methods for estimating synonymous (dS) and nonsynonymous (dN) nucleotide substitution rates are inapplicable here because a nucleotide change can be simultaneously synonymous and nonsynonymous when both reading frames involved are considered. We have developed a simple method that can estimate dN/dS and test for the action of natural selection in each relevant reading frame of the overlapping genes. Our method is an extension of the modified Nei-Gojobori method previously developed for nonoverlapping genes. We confirmed the reliability of our method using extensive computer simulation. Applying this method, we studied the longest human sense–antisense overlapping gene pair, LRRC8E and ENSG00000214248. Although LRRC8E (leucine-rich repeat containing eight family, member E) is known to regulate cell size, the function of ENSG00000214248 is unknown. Our analysis revealed purifying selection on ENSG00000214248 and suggested that it originated in the common ancestor of bony vertebrates. PMID:25552532

Wei, Xinzhu; Zhang, Jianzhi

2015-01-01

399

Integrated data search and access to geophysical data for Geohazards Supersites and Natural Laboratories  

NASA Astrophysics Data System (ADS)

The Geohazards Supersites and Natural Laboratories (GSNL) are committed to sharing space-based and ground-based geophysical data and building collaborations to better understand Earth processes and mitigate the societal hazards related to the dynamic Earth. GSNL is global with locations in Turkey, Japan, China, Italy, Haiti the United States (e.g. Hawaii and the western U.S.) and elsewhere. The UNAVCO Data Center in Boulder, Colorado, archives and distributes geodesy data and products in the GPS/GNSS, InSAR, and LiDAR domains. UNAVCO has an open access data policy and strives to provide catalogs and data access tools for all users. In an effort to create a unified data and metadata access capability for geodesy data centers in general and for GSNL in particular, UNAVCO and our partners, have designed and implemented software for simplified access called the Geodesy Seamless Archive Centers (GSAC). GSAC is a web services based technology to facilitate data discovery and access. The GSAC technology leverages several well-accepted geodesy data and metadata formats, and identifies a relatively small set of required and recommended metadata for the basic installation. Additional optional metadata can be defined at individual data centers. The GSAC services utilize a repository layer implemented at each data center, and a service layer to identify and present the required metadata elements along with any data center-specific services and capabilities. The software for the GSAC is available through SourceForge, and any geodesy data archive can download the code and implement GSAC services for their repository; doing so will provide the data center's users with the ability to use common query and access mechanisms with other GSAC data centers. Further, optional federation of individual GSAC data centers is facilitated through the GSAC software. GSAC would significantly simplify data access and integration, while enhancing data sharing around the world. GSAC is an excellent tool for advancing the goals of GSNL and helping to make the world a safer place through simple data integration.

Rowan, L.; Baker, S.; Wier, S.; Boler, F. M.; Meertens, C. M.; Amelung, F.

2013-12-01

400

Elevated Bacterial Abundance in Laboratory-Grown and Naturally Occurring Frost Flowers Under Late Winter Conditions  

NASA Astrophysics Data System (ADS)

Sea ice has been identified as an important microbial habitat, with bacteria and other microbes concentrated in the brine inclusions between ice crystals. Frost flowers, thought to draw brine from underlying sea ice, have not been characterized from a microbial standpoint. To test whether frost flowers serve as an upward vector of bacteria contained within sea ice brines we grew frost flowers in a freezer laboratory (air temperature of -21°C) from saline water spiked with the mesophilic (and thus passive under experimental conditions) bacterium Halomonas pacifica. Salinity of melted samples was measured and bacterial abundance determined by epifluorescent microscopy. Bacterial counts scaled to ice-melt volume averaged 2.82 x 106 ml-1 for frost flowers, compared to 9.47 x 105 ml-1 for underlying ice (3 x higher). Bacterial counts also correlated significantly with salinity (maximum value of 62.5 psu) for frost flowers, brine skim, and ice (df = 17, r = 0.59, p < 0.0001). Segregation coefficients were calculated to describe the efficiency of transport of both cells and salt from the starting solution into frost flowers. From these coefficients an enrichment index was calculated to test for bacterial concentration into frost flowers at a different rate than salt. Analysis with a Student’s T-test (df = 24, t = 0.306, p = .76) indicated that cells and salt were not transported into frost flowers with a significantly different efficiency. To test these findings in the field we then collected frost flowers (and related samples) from new sea ice near Barrow, Alaska in April 2009. Bacterial counts were significantly elevated (again, a 3-fold increase) in natural frost flowers (mean = 2.73 x 105 ml-1) compared to underlying sea ice (mean = 8.46 x 104 cells ml-1). For all field samples collected (frost flowers, underlying brine skim and sea ice, as well as snow), bacterial abundance correlated significantly with salinity (maximum value 124 psu, df = 40, r = 0.60, p < 0.0001). The presence of elevated numbers of bacteria in frost flowers may have implications for the previously observed chemical reactions that take place in them, especially if microbial activity can be shown to occur in this unique low temperature, low water activity microbial habitat.

Bowman, J. S.; Deming, J. W.

2009-12-01

401

Evidence of Natural Selection Acting on a Polymorphic Hybrid Incompatibility Locus in Mimulus.  

PubMed

As a common cause of reproductive isolation in diverse taxa, hybrid incompatibilities are fundamentally important to speciation. A key question is which evolutionary forces drive the initial substitutions within species that lead to hybrid dysfunction. Previously, we discovered a simple genetic incompatibility that causes nearly complete male sterility and partial female sterility in hybrids between the two closely related yellow monkeyflower species Mimulus guttatus and Mimulus nasutus. In this report, we fine map the two major incompatibility loci - hybrid male sterility 1 (hms1) and hybrid male sterility 2 (hms2) - to small nuclear genomic regions (each < 70 kb) that include strong candidate genes. With this improved genetic resolution, we also investigate the evolutionary dynamics of hms1 in a natural population of M. guttatus known to be polymorphic at this locus. Using classical genetic crosses and population genomics, we show that a 320-kb region containing the hms1 incompatibility allele has risen to intermediate frequency in this population by strong natural selection. This finding provides direct evidence that natural selection within plant species can lead to hybrid dysfunction between species. PMID:25428983

Sweigart, Andrea L; Flagel, Lex E

2014-11-25

402

Effects of ultraviolet radiation on early larval stages of the Alpine newt, Triturus alpestris , under natural and laboratory conditions  

Microsoft Academic Search

Although Alpine newts (Triturus alpestris) are found at altitudes up to 2500 m, their larvae proved to be extremely sensitive to UV radiation when exposed in clear\\u000a tapwater to natural sunlight or to comparable artificial UV-B radiation in the laboratory. The experiments revealed severe\\u000a skin damages (lysis of epithelial cells) and mortality after a few days of exposure. In their

Alexander M. Nagl; Rudolf Hofer

1997-01-01

403

Interaction-based evolution: how natural selection and nonrandom mutation work together  

PubMed Central

Background The modern evolutionary synthesis leaves unresolved some of the most fundamental, long-standing questions in evolutionary biology: What is the role of sex in evolution? How does complex adaptation evolve? How can selection operate effectively on genetic interactions? More recently, the molecular biology and genomics revolutions have raised a host of critical new questions, through empirical findings that the modern synthesis fails to explain: for example, the discovery of de novo genes; the immense constructive role of transposable elements in evolution; genetic variance and biochemical activity that go far beyond what traditional natural selection can maintain; perplexing cases of molecular parallelism; and more. Presentation of the hypothesis Here I address these questions from a unified perspective, by means of a new mechanistic view of evolution that offers a novel connection between selection on the phenotype and genetic evolutionary change (while relying, like the traditional theory, on natural selection as the only source of feedback on the fit between an organism and its environment). I hypothesize that the mutation that is of relevance for the evolution of complex adaptation—while not Lamarckian, or “directed” to increase fitness—is not random, but is instead the outcome of a complex and continually evolving biological process that combines information from multiple loci into one. This allows selection on a fleeting combination of interacting alleles at different loci to have a hereditary effect according to the combination’s fitness. Testing and implications of the hypothesis This proposed mechanism addresses the problem of how beneficial genetic interactions can evolve under selection, and also offers an intuitive explanation for the role of sex in evolution, which focuses on sex as the generator of genetic combinations. Importantly, it also implies that genetic variation that has appeared neutral through the lens of traditional theory can actually experience selection on interactions and thus has a much greater adaptive potential than previously considered. Empirical evidence for the proposed mechanism from both molecular evolution and evolution at the organismal level is discussed, and multiple predictions are offered by which it may be tested. Reviewers This article was reviewed by Nigel Goldenfeld (nominated by Eugene V. Koonin), Jürgen Brosius and W. Ford Doolittle. PMID:24139515

2013-01-01

404

Moving from the laboratory to the field: Adding natural environmental conditions to toxicology testing  

EPA Science Inventory

While laboratory toxicology tests are generally easy to perform, cost effective and readily interpreted, they have been criticized for being unrealistic. In contrast, field tests are considered realistic while producing results that are difficult to interpret and expensive. To ...

405

Natural Selection and Molecular Evolution in PTC, a Bitter-Taste Receptor Gene  

PubMed Central

The ability to taste phenylthiocarbamide (PTC) is a classic phenotype that has long been known to vary in human populations. This phenotype is of genetic, epidemiologic, and evolutionary interest because the ability to taste PTC is correlated with the ability to taste other bitter substances, many of which are toxic. Thus, variation in PTC perception may reflect variation in dietary preferences throughout human history and could correlate with susceptibility to diet-related diseases in modern populations. To test R. A. Fisher’s long-standing hypothesis that variability in PTC perception has been maintained by balancing natural selection, we examined patterns of DNA sequence variation in the recently identified PTC gene, which accounts for up to 85% of phenotypic variance in the trait. We analyzed the entire coding region of PTC (1,002 bp) in a sample of 330 chromosomes collected from African (n=62), Asian (n=138), European (n=110), and North American (n=20) populations by use of new statistical tests for natural selection that take into account the potentially confounding effects of human population growth. Two intermediate-frequency haplotypes corresponding to “taster” and “nontaster” phenotypes were found. These haplotypes had similar frequencies across Africa, Asia, and Europe. Genetic differentiation between the continental population samples was low (FST=0.056) in comparison with estimates based on other genes. In addition, Tajima’s D and Fu and Li’s D and F statistics demonstrated a significant deviation from neutrality because of an excess of intermediate-frequency variants when human population growth was taken into account (P<.01). These results combine to suggest that balancing natural selection has acted to maintain “taster” and “nontaster” alleles at the PTC locus in humans. PMID:14997422

Wooding, Stephen; Kim, Un-kyung; Bamshad, Michael J.; Larsen, Jennifer; Jorde, Lynn B.; Drayna, Dennis

2004-01-01

406

Aggression and feeding of hatchery-reared and naturally reared steelhead (Oncorhynchus mykiss) fry in a laboratory flume and a comparison with observations in natural streams  

USGS Publications Warehouse

We quantified the aggression and feeding of naturally reared steelhead (Oncorhynchus mykiss) fry stocked into a laboratory flume with naturally reared fry or hatchery-reared fry from conventional and enriched rearing environments at three densities in the presence and absence of predators, and compared the aggression and feeding observed in the flume to that observed in two streams. Steelhead fry attack rate increased with density and was reduced in the presence of predators, but was not affected by rearing treatment. Threat rate appeared to increase with density and was significantly affected by rearing treatment combination, but was not significantly affected by predator presence. Feeding rate was not affected by density or rearing treatment, but was reduced in the presence of predators. The rate of aggression by steelhead fry in two streams was lower than that observed in the laboratory and did not increase with density. Rates of aggression and feeding of hatchery-reared and wild steelhead fry were not significantly different in the streams. Overall, we found no evidence that hatchery rearing environments caused higher aggression in steelhead fry. Laboratory observations of salmonid aggression, particularly at high density, may not reflect aggression levels in the wild. ?? 2005 NRC.

Riley, S.C.; Tatara, C.P.; Scheurer, J.A.

2005-01-01

407

[Habitat selection of four sympatric pheasants in Guanshan National Nature Reserve, Jiangxi, China].  

PubMed

Habitat selection of four sympatric pheasants (Syrmaticus ellioti, Lophura nycthemera, Pucrasia macrolopha and Bumbusicola thoracica) was studied in Guanshan National Nature Reserve, Jiangxi, China from October 2009 to November 2010. We measured seventeen ecological factors across 388 sites used by the four pheasants by direct observation in six transects. The results show that the pheasants preferred broad-leaved forest and coniferous forest and a sunny or semi-shaded slope. There were differences in elevation, degree of slope, arbor coverage, shrub coverage, shrub quantity, shrub height, herbage cover, herbage species, herbage quantity, leaf litter coverage, distance to water and arbor species between the habitat selected by the four pheasants. Canonical scores indicated that the four pheasants differed in habitat selection to some extent. A stepwise discriminant analysis revealed that elevation, herbage quantity, shrub height, distance to water, shrub cover, arbor cover, degree of slope, leaf litter cover, shrub quantity and herbage cover were the critical factors distinguishing habitat selection between the species. Predicted classification accuracy of the model was 74.7%. PMID:22467392

Liu, Peng; Huang, Xiao-Feng; Gu, Shu-Sheng; Lu, Chang-Hu

2012-04-01

408

Signatures of Demographic History and Natural Selection in the Human Major Histocompatibility Complex Loci  

PubMed Central

Many lines of evidence show that several HLA loci have experienced balancing selection. However, distinguishing among demographic and selective explanations for patterns of variation observed with HLA genes remains a challenge. In this study we address this issue using data from a diverse set of human populations at six classical HLA loci and, employing a comparative genomics approach, contrast results for HLA loci to those for non-HLA markers. Using a variety of analytic methods, we confirm and extend evidence for selection acting on several HLA loci. We find that allele frequency distributions for four of the six HLA loci deviate from neutral expectations and show that this is unlikely to be explained solely by demographic factors. Other features of HLA variation are explained in part by demographic history, including decreased heterozygosity and increased LD for populations at greater distances from Africa and a similar apportionment of genetic variation for HLA loci compared to putatively neutral non-HLA loci. On the basis of contrasts among different HLA loci and between HLA and non-HLA loci, we conclude that HLA loci bear detectable signatures of both natural selection and demographic history. PMID:16702436

Meyer, Diogo; Single, Richard M.; Mack, Steven J.; Erlich, Henry A.; Thomson, Glenys

2006-01-01

409

Natural selection on floral traits of female Silene dioica by a sexually transmitted disease.  

PubMed

Floral traits endowing high reproductive fitness can also affect the probability of plants contracting sexually transmitted diseases. We explore how variations in floral traits influence the fitness of Silene dioica females in their interactions with pollinators carrying pollen or spores of the sterilizing anther-smut fungus Microbotryum violaceum. We collected healthy and infected plants in a highly diseased population and grew them under conditions that 'cure' infected individuals, and used standard regression methods to detect natural selection on floral traits. Narrow-sense heritabilities, coefficients of additive genetic variation (CV(A)) and genetic correlations among traits were estimated from paternal half-sib groups. Pollinator preferences imposed strong direct and directional selection on traits affecting female attractiveness and pollen-/spore-capturing abilities. Levels of additive genetic variance were high in these traits, suggesting that rapid responses to selection are possible. By considering our results in the light of spatial and temporal heterogeneity resulting from the colonization dynamics typical for this species, we suggest that the conflicting selective effects of pollen/spore loads lead to the maintenance of genetic variation in these traits. PMID:16441754

Giles, Barbara E; Pettersson, Tor Mikael; Carlsson-Granér, Ulla; Ingvarsson, Pär K

2006-01-01

410

Soil organic carbon content estimation with laboratory-based visible-near-infrared reflectance spectroscopy: feature selection.  

PubMed

This study, with Yixing (Jiangsu Province, China) and Honghu (Hubei Province, China) as study areas, aimed to compare the successive projection algorithm (SPA) and the genetic algorithm (GA) in spectral feature selection for estimating soil organic carbon (SOC) contents with visible-near-infrared (Vis-NIR) reflectance spectroscopy and further to assess whether the spectral features selected from one site could be applied to another site. The SOC content and Vis-NIR reflectance spectra of soil samples were measured in the laboratory. Savitzky-Golay smoothing and log10(1/R) (R is reflectance) were used for spectral preprocessing. The reflectance spectra were resampled using different spacing intervals ranging from 2 to 10 nm. Then, SPA and GA were conducted for selecting the spectral features of SOC. Partial least square regression (PLSR) with full-spectrum PLSR and the spectral features selected by SPA (SPA-PLSR) and GA (GA-PLSR) were calibrated and validated using independent datasets, respectively. Moreover, the spectral features selected from one study area were applied to another area. Study results showed that, for the two study areas, the SPA-PLSR and GA-PLSR improved estimation accuracies and reduced spectral variables compared with the full spectrum PLSR in estimating SOC contents; GA-PLSR obtained better estimation results than SPA-PLSR, whereas SPA was simpler than GA, and the spectral features selected from Yixing could be well applied to Honghu, but not the reverse. These results indicated that the SPA and GA could reduce the spectral variables and improve the performance of PLSR model and that GA performed better than SPA in estimating SOC contents. However, SPA is simpler and time-saving compared with GA in selecting the spectral features of SOC. The spectral features selected from one dataset could be applied to a target dataset when the dataset contains sufficient information adequately describing the variability of samples of the target dataset. PMID:25061784

Shi, Tiezhu; Chen, Yiyun; Liu, Huizeng; Wang, Junjie; Wu, Guofeng

2014-01-01

411

Alfred Russel Wallace and the Road to Natural Selection, 1844-1858.  

PubMed

Conventional wisdom has had it that the naturalist Alfred Russel Wallace and his colleague Henry Walter Bates journeyed to the Amazon in 1848 with two intentions in mind: to collect natural history specimens, and to consider evidential materials that might reveal the causal basis of organic evolution. This understanding has been questioned recently by the historian John van Wyhe, who points out that with regard to the second matter, at least, there appears to be no evidence of a "smoking gun" variety proving it so. In the present essay the circumstances of Wallace's interest in the matter are reviewed, and van Wyhe is taken to task with alternate explanations for the facts he introduces in his argument. The conclusion is that Wallace almost certainly did have the second objective in mind when he left for both the Amazon, and the Far East. Keywords: Alfred Russel Wallace, Henry Walter Bates, evolution, natural selection. PMID:25424743

Smith, Charles H

2014-11-26

412

Automated ion-selective electrode method for determining fluoride in natural waters  

USGS Publications Warehouse

An automated fluoride method which uses AutoAnalyzer modules in conjunction with a fluoride ion-selective electrode was evaluated. The results obtained on 38 natural water samples are in excellent agreement with those determined by a similar manual method (average difference = 0.026 mg/l). An average fluoride concentration of 0.496 mg/l was found when several natural water samples were spiked with 0.50 mg/l fluoride. Aluminum is the only significant interfering substance, and it can be easily tolerated if its concentration does not exceed 2 mg/l. Thirty samples were analyzed per hour over a concentration range of 0-2 mg/l.

Erdmann, D.E.

1975-01-01

413

On the causal efficacy of natural selection: A response to Richards' critique of the standard interpretation.  

PubMed

Given the amount of literature devoted to the reasoning used in Darwin's Origin of Species, an interpretation seeking to revise the standard take on Darwin's methodology is unexpected. Yet, Richards (1997, 1998, 2005) challenges the view that Darwin drew an analogy in the Origin on the grounds that such a strategy could not support the possibility of a new species emerging. I suggest, however, that how one interprets causal efficacy is intimately connected with Darwin's use of analogy. A more robust conception of natural selection, as found in the Origin, supports the standard interpretation, significantly weakening Richards' charge of a paradox. PMID:24231184

Sullivan-Clarke, Andrea

2013-12-01

414

Laboratory lore and research practices in the experimental analysis of human behavior: Subject selection  

E-print Network

Discusses data on S selection processes obtained from a literature survey and 52 members of the Association for Behavior Analysis. Choice of S samples is discussed in terms of marker variables, including age, gender, and ...

Morris, Edward K.; Johnson, Lisa M.; Todd, James T.; Higgins, Stephen T.

1988-01-01

415

Evaluation of toxicity of selected insecticides against thrips on cotton in laboratory bioassays  

Technology Transfer Automated Retrieval System (TEKTRAN)

Adult vial technique (AVT) and spray table bioassays were conducted to evaluate toxicity of selected insecticides against immature and adult Western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). In AVT, technical insecticides comprising of organophosphates (d...

416

ORGANOTIN TOXICITY STUDIES CONDUCTED WITH SELECTED MARINE ORGANISMS AT EPA'S ENVIRONMENTAL RESEARCH LABORATORY, GULF BREEZE, FLORIDA  

EPA Science Inventory

Studies on effect of bis(tri-n-butyltin)oxide (TBTO) and other organotins on marine species have been conducted at the U.S. Environmental Protection Agency's laboratory at Gulf Breeze, Florida, since 1983. First studies were done on two species of algae, Skeletonema costatum and ...

417

Chemoselective Reactions of Citral: Green Syntheses of Natural Perfumes for the Undergraduate Organic Laboratory  

ERIC Educational Resources Information Center

Chemoselectivity is a central concept in organic synthesis and may be readily appreciated in the context of the fragrant, polyfunctional natural product citral. We describe three single-step reactions students may perform on citral to synthesize other natural perfumes: citronellal, geraniol, nerol, or epoxycitral. Each of the reactions uses a…

Cunningham, Anna D.; Ham, Eun Y.; Vosburg, David A.

2011-01-01

418

Construction of stable laboratory and industrial yeast strains expressing a foreign gene by integrative transformation using a dominant selection system.  

PubMed

An expression cassette of mouse dihydrofolate reductase (Mdhfr) cDNA under control of the yeast cytochrome c promoter was inserted in a yeast plasmid containing the ARS1 sequence. The ARS replicating function was destroyed by BglII treatment prior to yeast transformation. Using this linearized plasmid, genomic transformants could be obtained from either laboratory or industrial strains of bakers' yeast based on direct methotrexate (MTX)-resistance selection. The entire sequence of the linearized plasmid was integrated by homologous recombination at the ARS region of the host chromosome. The results indicate that repetitive and homologous recombination occurs readily in such transformations. The stability of the constructed integrants was more than 99.95% per generation in non-selective medium, and tandem repeats of up to six copies (i.e., about 44 kb) were not changed even after 30 generations in rich medium. Expression in rich medium of cointegrated, human interleukin 2 cDNA under control of the triose phosphate isomerase promoter was shown by Western blot experiments in both laboratory and industrial yeast strains. Furthermore, a comparison of the transcription efficiency of the Mdhfr gene in the chromosome with that in the plasmid revealed that the efficiency was almost proportional to the number of gene copies, irrespective of the location of the transcription unit. These results show that by using the MTX/Mdhfr dominant selection-amplification system one can construct stable recombinant yeast strains suitable for heterologous gene expression in laboratory as well as in industrial fermentation conditions. PMID:3556323

Zhu, J; Contreras, R; Fiers, W

1986-01-01

419

Scaffolding Preservice Science Teachers' Evidence-Based Arguments During an Investigation of Natural Selection  

NASA Astrophysics Data System (ADS)

In this qualitative case study, preservice science teachers (PSTs) enrolled in their advanced methods course participated in a complex, data-rich investigation based on an adapted version of the Struggle for Survival curriculum. Fundamental to the investigation was the use of the Galapagos Finches software and an emphasis on giving priority to evidence and constructing evidence-based arguments. The questions that guided the research were: (1) What is the nature of the scientific arguments developed by PSTs? (2) How do PSTs go about constructing scientific arguments (emphasis on processes and strategies)? (3) In what ways do the scaffolds embedded in the Galapagos Finches software influence the development of PSTs arguments? Two pairs of PSTs were selected for in-depth examination. The primary sources of data were the electronic artifacts generated in the Galapagos Finches software environment and the videotaped interactions of both pairs as they investigated the data set, constructed and revised their arguments, engaged in peer review sessions, and presented their arguments to the class at the end of the unit. Four major patterns emerged through analysis of the data. First, using the software, PSTs consistently constructed claims that were linked to evidence from the investigation. Second, although PSTs consistently grounded their arguments in evidence, they still exhibited a number of limitations reported in the literature. Third, the software served as a powerful vehicle for revealing PSTs knowledge of evolution and natural selection. Finally, the PSTs approach to the task had a strong influence on the way they used the software.

Zembal-Saul, Carla; Munford, Danusa; Crawford, Barbara; et al.

2002-08-01

420

Multi-modal hard x-ray imaging with a laboratory source using selective reflection from a mirror  

PubMed Central

Multi-modal hard x-ray imaging sensitive to absorption, refraction, phase and scattering contrast is demonstrated using a simple setup implemented with a laboratory source. The method is based on selective reflection at the edge of a mirror, aligned to partially reflect a pencil x-ray beam after its interaction with a sample. Quantitative scattering contrast from a test sample is experimentally demonstrated using this method. Multi-modal imaging of a house fly (Musca domestica) is shown as proof of principle of the technique for biological samples. PMID:24761297

Pelliccia, Daniele; Paganin, David M.

2014-01-01

421

Interplay of Adaptive Selection and Synergistic Performance: As an example of natural selection and self-organization  

Microsoft Academic Search

The purpose of this study is to elucidate the eect of self-organizing processes, in particular the synergistic increase in performance of individuals in diverse collectives, on the adaptive selection process (the engine of variation generation, selection and amplification). The systems under consid- eration include the more traditional systems undergoing adaptive selection as in biology and ecology, as well as more

Norman L. Johnson; Jennifer H. Watkins

422

Copy number variants and selective sweeps in natural populations of the house mouse (Mus musculus domesticus).  

PubMed

Copy-number variants (CNVs) may play an important role in early adaptations, potentially facilitating rapid divergence of populations. We describe an approach to study this question by investigating CNVs present in natural populations of mice in the early stages of divergence and their involvement in selective sweeps. We have analyzed individuals from two recently diverged natural populations of the house mouse (Mus musculus domesticus) from Germany and France using custom, high-density, comparative genome hybridization arrays (CGH) that covered almost 164 Mb and 2444 genes. One thousand eight hundred and sixty one of those genes we previously identified as differentially expressed between these populations, while the expression of the remaining genes was invariant. In total, we identified 1868 CNVs across all 10 samples, 200 bp to 600 kb in size and affecting 424 genic regions. Roughly two thirds of all CNVs found were deletions. We found no enrichment of CNVs among the differentially expressed genes between the populations compared to the invariant ones, nor any meaningful correlation between CNVs and gene expression changes. Among the CNV genes, we found cellular component gene ontology categories of the synapse overrepresented among all the 2444 genes tested. To investigate potential adaptive significance of the CNV regions, we selected six that showed large differences in frequency of CNVs between the two populations and analyzed variation in at least two microsatellites surrounding the loci in a sample of 46 unrelated animals from the same populations collected in field trappings. We identified two loci with large differences in microsatellite heterozygosity (Sfi1 and Glo1/Dnahc8 regions) and one locus with low variation across the populations (Cmah), thus suggesting that these genomic regions might have recently undergone selective sweeps. Interestingly, the Glo1 CNV has previously been implicated in anxiety-like behavior in mice, suggesting a differential evolution of a behavioral trait. PMID:24917877

Bryk, Jaros?aw; Tautz, Diethard

2014-01-01

423

Nonsynonymous SNPs: validation characteristics, derived allele frequency patterns, and suggestive evidence for natural selection.  

PubMed

We experimentally investigated more than 1,200 entries in dbSNP that would change amino-acids (nsSNPs), using various subsets of DNA samples drawn from 18 global populations (approximately 1,000 subjects in total). First, we mined the data for any SNP features that correlated with a high validation rate. Useful predictors of valid SNPs included multiple submissions to dbSNP, having a dbSNP validation statement, and being present in a low number of ESTs. Together, these features improved validation rates by almost 10-fold. Higher-abundance SNPs (e.g., T/C variants) also validated more frequently. Second, we considered derived alleles and noted a considerably (approximately 10%) increased average derived allele frequency (DAF) in Europeans vs. Africans, plus a further increase in some other populations. This was not primarily due to an SNP ascertainment bias, nor to the effects of natural selection. Instead, it can be explained as a drift-based, progressive increase in DAF that occurs over many generations and becomes exaggerated during population bottlenecks. This observation could be used as the basis for novel DAF-based tests for comparing demographic histories. Finally, we considered individual marker patterns and identified 37 SNPs with allele frequency variance or FST values consistent with the effects of population-specific natural selection. Four particularly striking clusters of these markers were apparent, and three of these coincide with genes/regions from among only several dozen such domains previously suggested by others to carry signatures of selection. PMID:16429399

Fredman, David; Sawyer, Sarah L; Strömqvist, Linda; Mottagui-Tabar, Salim; Kidd, Kenneth K; Wahlestedt, Claes; Chanock, Stephen J; Brookes, Anthony J

2006-02-01

424

Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines  

SciTech Connect

Selective NOx Recirculation (SNR) involves cooling the engine exhaust gas and then adsorbing the oxides of nitrogen (NOx) from the exhaust stream, followed by the periodic desorption of NOx. By returning the desorbed, concentrated NOx into the engine intake and through the combustion chamber, a percentage of the NOx is decomposed during the combustion process. An initial study of NOx decomposition during lean-burn combustion was concluded in 2004 using a 1993 Cummins L10G 240hp natural gas engine. It was observed that the air/fuel ratio, injected NO (nitric oxide) quantity and engine operating points affected NOx decomposition rates of the engine. Chemical kinetic modeling results were also used to determine optimum NOx decomposition operating points and were published in the 2004 annual report. A NOx decomposition rate of 27% was measured from this engine under lean-burn conditions while the software model predicted between 35-42% NOx decomposition for similar conditions. A later technology 1998 Cummins L10G 280hp natural gas engine was procured with the assistance of Cummins Inc. to replace the previous engine used for 2005 experimental research. The new engine was equipped with an electronic fuel management system with closed-loop control that provided a more stable air/fuel ratio control and improved the repeatability of the tests. The engine was instrumented with an in-cylinder pressure measurement system and electronic controls, and was adapted to operate over a range of air/fuel ratios. The engine was connected to a newly commissioned 300hp alternating current (AC) motoring dynamometer. The second experimental campaign was performed to acquire both stoichiometric and slightly rich (0.97 lambda ratio) burn NOx decomposition rates. Effects of engine load and speed on decomposition were quantified, but Exhaust Gas Recirculation (EGR) was not varied independently. Decomposition rates of up to 92% were demonstrated. Following recommendations at the 2004 ARES peer review meeting at Argonne National Laboratories, in-cylinder pressure was measured to calculate engine indicated mean effective pressure (IMEP) changes due to NOx injections and EGR variations, and to observe conditions in the cylinder. The third experimental campaign gathered NOx decomposition data at 800, 1200 and 1800 rpm. EGR was added via an external loop, with EGR ranging from zero to the point of misfire. The air/fuel ratio was set at both stoichiometric and slightly rich conditions, and NOx decomposition rates were calculated for each set of runs. Modifications were made to the engine exhaust manifold to record individual exhaust temperatures. The three experimental campaigns have provided the data needed for a comprehensive model of NOx decomposition during the combustion process, and data have confirmed that there was no significant impact of injected NO on in-cylinder pressure. The NOx adsorption system provided by Sorbent Technologies Corp. (Twinsburg, OH), comprised a NOx adsorber, heat exchanger and a demister. These components were connected to the engine, and data were gathered to show both the adsorption of NOx from the engine, and desorption of NOx from the carbon-based sorbent material back into the engine intake, using a heated air stream. In order to quantify the NOx adsorption/desorption characteristics of the sorbent material, a bench top adsorption system was constructed and instrumented with thermocouples and the system output was fed into a NOx analyzer. The temperature of this apparatus was controlled while gathering data on the characteristics of the sorbent material. These data were required for development of a system model. Preliminary data were gathered in 2005, and will continue in early 2006. To assess the economic benefits of the proposed SNR technology the WVU research team has been joined in the last quarter by Dr Richard Turton (WVU-Chemical Engineering), who is modeling, sizing and costing the major components. The tasks will address modeling and preliminary design of the heat exchanger, demister and NOx sorbent chamber s

Nigel Clark; Gregory Thompson; Richard Atkinson; Richard Turton; Chamila Tissera; Emre Tatli; Andy Zimmerman

2005-12-28

425

Selective silencing of autoreactive B lymphocytes-Following the Nature's way.  

PubMed

A novel approach for the selective silencing of targeted autoreactive B lymphocytes is reviewed that mimics the physiological mechanisms for suppressing B cell activity. It is based on the use of bi- or tri-specific chimeric antibodies that cross-link BCRs with a pre-selected antigen-binding specificity with one or more inhibitory types of receptors on the surface of the same disease-associated B lymphocyte. The effect of these engineered antibodies was proved to be specific as they only suppressed the production of the targeted pathological antibodies while sparing those with other specificities. The administration of the chimeric molecules to lupus-prone MRL/lpr mice resulted in decreased levels of disease-associated IgG autoantibodies and of proteinuria, in the prevention of cutaneous lesions, in decreased sizes of the lymphoid organs and in prolonged survival. These results prove that it is indeed possible to selectively silence unwanted B lymphocytes as well as to significantly delay the natural course of a spontaneous antibody-mediated autoimmune disease. PMID:20601201

Nikolova, Kalina A; Mihaylova, Nikolina M; Voynova, Elisaveta N; Tchorbanov, Andrey I; Voll, Reinhard E; Vassilev, Tchavdar L

2010-09-01

426

Process for selecting NEAMS applications for access to Idaho National Laboratory high performance computing resources  

SciTech Connect

INL has agreed to provide participants in the Nuclear Energy Advanced Mod- eling and Simulation (NEAMS) program with access to its high performance computing (HPC) resources under sponsorship of the Enabling Computational Technologies (ECT) program element. This report documents the process used to select applications and the software stack in place at INL.

Michael Pernice

2010-09-01

427

Geospatial Toolkits and Resource Maps for Selected Countries from the National Renewable Energy Laboratory (NREL)  

DOE Data Explorer

NREL also has developed high-resolution resource maps and data products for selected, individual countries using its Geospatial Toolkit. Countries with both a GsT product and related maps and data products are Afghanistan, Bhutan, Northwest India, and Pakistan. [Taken and edited from http://www.nrel.gov/international/geospatial_toolkits.html

428

Novel Experiments in Physics II. A Selection of Laboratory Notes Now Used in Colleges and Universities.  

ERIC Educational Resources Information Center

This second volume, a compilation of reprints of experimental notes in physics, was prepared by the American Association of Physics Teachers (AAPT) Committee on Apparatus and by the AAPT Executive Office in response to requests received by the Association for a completely new edition. The goal of the Committee was to provide a selection of…

American Association of Physics Teachers, Washington, DC.

429

LABORATORY STUDIES ON THE STABILITY AND TRANSPORT OF INORGANIC COLLOIDS THROUGH NATURAL AQUIFER MATERIAL  

EPA Science Inventory

The stability and transport of radio-labeled Fe2O3 particles were studied using laboratory batch and column techniques. Core material collected from shallow sand and gravel aquifer was used as the immobile column matrix material. Variables in the study included flow rate, pH, i...

430

PROJECTS IN IMAGINATIVE NATURE EDUCATION, SURVEY REPORT AND OUTDOOR LABORATORY PLAN.  

ERIC Educational Resources Information Center

THIS PLAN SUGGESTS HOW THE MID HUDSON-CATSKILLS MUSEUM CAN WORK CREATIVELY WITH COOPERATING SCHOOL DISTRICTS TO STRENGTHEN THEIR CURRICULUMS THROUGH OUTDOOR EDUCATION. THE RESULT OF THIS COOPERATIVE ENDEAVOR IS TO BE AN OUTDOOR LABORATORY CALLED "GATEWAY CENTER" LOCATED NEAR NEW PALTZ, NEW YORK. PART 1 CONTAINS (1) BACKGROUND INFORMATION, (2)…

National Audubon Society, New York, NY.

431

Allergic reactions to glove materials Gloves are common in research laboratories. The selection  

E-print Network

-immune reaction affecting the skin, and should not be confused with an allergy. Exposure to glove materials can to natural rubber latex proteins and/or synthetic chemicals in the glove material. Latex allergy is an Ig a protein. Latex products can cause Type I allergy as well as Type IV allergy. Type I allergy to latex

Shull, Kenneth R.

432

Natural selection on a measure of parasite resistance varies across ages and environmental conditions in a wild mammal  

E-print Network

Natural selection on a measure of parasite resistance varies across ages and environmental Individuals in natural populations are under constant threat of infection from parasitic organisms that have detrimental effects on host condition and fitness (Poulin, 2007). Infection and damage by parasites may

Lummaa, Virpi

433

RESPONSES OF ZOOPLANKTON AND CHAOBORUS TO TEMEPHOS IN A NATURAL POND AND IN THE LABORATORY  

EPA Science Inventory

Application of the organophosphorus insecticide temephos to a natural pond in central Minnesota was followed by reduction within 24 hr in all cladocerans, in Diaptomus leptopus and in Chaoborus americanus, and increases in cyclopoid copepods, copepod nauplii and rotifer Keratella...

434

Middle/high school students in the research laboratory: A summer internship program emphasizing the interdisciplinary nature of biology.  

PubMed

We describe an eight-week summer Young Scientist in Training (YSIT) internship program involving middle and high school students. This program exposed students to current basic research in molecular genetics, while introducing or reinforcing principles of the scientific method and demonstrating the uses of mathematics and chemistry in biology. For the laboratory-based program, selected students from Baltimore City Schools working in groups of three were teamed with undergraduate research assistants at Morgan State University. Teams were assigned a project that was indirectly related to our laboratory research on the characterization of gene expression in Caenorhabditis elegans. At the end of the program, teams prepared posters detailing their accomplishments, and presented their findings to parents and faculty members during a mini-symposium. The posters were also submitted to the respective schools and the interns were offered a presentation of their research at local high school science fairs. PMID:21638644

McMiller, Tracee; Lee, Tameshia; Saroop, Ria; Green, Tyra; Johnson, Casonya M

2006-03-01

435

Detection of the signature of natural selection in humans: evidence from the Duffy blood group locus.  

PubMed Central

The Duffy blood group locus, which encodes a chemokine receptor, is characterized by three alleles-FY*A, FY*B, and FY*O. The frequency of the FY*O allele, which corresponds to the absence of Fy antigen on red blood cells, is at or near fixation in most sub-Saharan African populations but is very rare outside Africa. The FST value for the FY*O allele is the highest observed for any allele in humans, providing strong evidence for the action of natural selection at this locus. Homozygosity for the FY*O allele confers complete resistance to vivax malaria, suggesting that this allele has been the target of selection by Plasmodium vivax or some other infectious agent. To characterize the signature of directional selection at this locus, we surveyed DNA sequence variation, both in a 1.9-kb region centered on the FY*O mutation site and in a 1-kb region 5-6 kb away from it, in 17 Italians and in a total of 24 individuals from five sub-Saharan African populations. The level of variation across both regions is two- to threefold lower in the Africans than in the Italians. As a result, the pooled African sample shows a significant departure from the neutral expectation for the number of segregating sites, whereas the Italian sample does not. The FY*O allele occurs on two major haplotypes in three of the five African populations. This finding could be due to recombination, recurrent mutation, population structure, and/or mutation accumulation and drift. Although we are unable to distinguish among these alternative hypotheses, it is likely that the two major haplotypes originated prior to selection on the FY*O mutation. PMID:10762551

Hamblin, M T; Di Rienzo, A

2000-01-01

436

Quantitative genetics of functional characters in Drosophila melanogaster populations subjected to laboratory selection  

Microsoft Academic Search

What are the genetics of phenotypes other than fitness, in outbred populations? To answer this question, the quantitative-genetic\\u000a basis of divergence was characterized for outbredDrosophila melanogaster populations that had previously undergone selection to enhance characters related to fitness. Line-cross analysis using first-generation\\u000a and second-generation hybrids from reciprocal crosses was conducted for two types of cross, each replicated fivefold. One\\u000a type

Henrique Teotónio; Margarida Matos; Michael R. Rose

2004-01-01

437

Natural selection and the conditions for existence: representational vs. conditional teleology in biological explanation.  

PubMed

Human intentional action, including the design and use of artifacts, involves the prior mental representation of the goal (end) and the means to achieve that goal. This representation is part of the efficient cause of the action, and thus can be used to explain both the action and the achievement of the end. This is intentional teleological explanation. More generally, teleological explanation that depends on the real existence of a representation of the goal (and the means to achieve it) can be called representational teleological explanation. Such explanations in biology can involve both external representations (e.g., ideas in the mind of God) and internal representations (souls, vital powers, entelechies, developmental programs, etc.). However, another type of explanation of intentional action (or any other process) is possible. Given that an action achieving a result occurs, the action can be explained as fulfilling the necessary conditions (means) for that result (end), and, reciprocally, the result explained by the occurrence of those necessary conditions. This is conditional teleological explanation. For organisms, natural selection is often understood metaphorically as the designer, intentionally constructing them for certain ends. Unfortunately, this metaphor is often taken rather too literally, because it has been difficult to conceive of another way to relate natural selection to the process of evolution. I argue that combining a conditional teleological explanation of organisms and of evolution provides such an alternative. This conditional teleology can be grounded in existence or survival. Given that an organism exists, we can explain its existence by the occurrence of the necessary conditions for that existence. This principle of the 'conditions for existence' was introduced by Georges Cuvier in 1800, and provides a valid, conditional teleological method for explaining organismal structure and behavior. From an evolutionary perspective, the conditions for existence are the range of boundary conditions within which the evolutionary process must occur. Moreover, evolutionary change itself can be subjected to conditional teleological explanation, because natural selection theory is primarily a theory about the relation between the conditions for the existence of organisms and the conditions for the existence of traits in populations. I show that failure to distinguish representational from conditional teleological explanation has confused previous attempts to clarify the relation of teleology to biology. PMID:16602488

Reiss, John O

2005-01-01

438

Compilation of minimum and maximum isotope ratios of selected elements in naturally occurring terrestrial materials and reagents  

USGS Publications Warehouse

Documented variations in the isotopic compositions of some chemical elements are responsible for expanded uncertainties in the standard atomic weights published by the Commission on Atomic Weights and Isotopic Abundances of the International Union of Pure and Applied Chemistry. This report summarizes reported variations in the isotopic compositions of 20 elements that are due to physical and chemical fractionation processes (not due to radioactive decay) and their effects on the standard atomic weight uncertainties. For 11 of those elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine, copper, and selenium), standard atomic weight uncertainties have been assigned values that are substantially larger than analytical uncertainties because of common isotope abundance variations in materials of natural terrestrial origin. For 2 elements (chromium and thallium), recently reported isotope abundance variations potentially are large enough to result in future expansion of their atomic weight uncertainties. For 7 elements (magnesium, calcium, iron, zinc, molybdenum, palladium, and tellurium), documented isotope-abundance variations in materials of natural terrestrial origin are too small to have a significant effect on their standard atomic weight uncertainties. This compilation indicates the extent to which the atomic weight of an element in a given material may differ from the standard atomic weight of the element. For most elements given above, data are graphically illustrated by a diagram in which the materials are specified in the ordinate and the compositional ranges are plotted along the abscissa in scales of (1) atomic weight, (2) mole fraction of a selected isotope, and (3) delta value of a selected isotope ratio. There are no internationally distributed isotopic reference materials for the elements zinc, selenium, molybdenum, palladium, and tellurium. Preparation of such materials will help to make isotope ratio measurements among laboratories comparable. The minimum and maximum concentrations of a selected isotope in naturally occurring terrestrial materials for selected chemical elements reviewed in this report are given below: Isotope Minimum mole fraction Maximum mole fraction -------------------------------------------------------------------------------- 2H 0 .000 0255 0 .000 1838 7Li 0 .9227 0 .9278 11B 0 .7961 0 .8107 13C 0 .009 629 0 .011 466 15N 0 .003 462 0 .004 210 18O 0 .001 875 0 .002 218 26Mg 0 .1099 0 .1103 30Si 0 .030 816 0 .031 023 34S 0 .0398 0 .0473 37Cl 0 .240 77 0 .243 56 44Ca 0 .020 82 0 .020 92 53Cr 0 .095 01 0 .095 53 56Fe 0 .917 42 0 .917 60 65Cu 0 .3066 0 .3102 205Tl 0 .704 72 0 .705 06 The numerical values above have uncertainties that depend upon the uncertainties of the determinations of the absolute isotope-abundance variations of reference materials of the elements. Because reference materials used for absolute isotope-abundance measurements have not been included in relative isotope abundance investigations of zinc, selenium, molybdenum, palladium, and tellurium, ranges in isotopic composition are not listed for these elements, although such ranges may be measurable with state-of-the-art mass spectrometry. This report is available at the url: http://pubs.water.usgs.gov/wri014222.

Coplen, T.B.; Hopple, J.A.; Böhlke, J.K.; Peiser, H.S.; Rieder, S.E.; Krouse, H.R.; Rosman, K.J.R.; Ding, T.; Vocke, R.D., Jr.; Revesz, K.M.; Lamberty, A.; Taylor, P.; De Bievre, P.

2002-01-01

439

Growth Phase-Coupled Changes of the Ribosome Profile in Natural Isolates and Laboratory Strains of Escherichia coli  

PubMed Central

The growth phase-dependent change in sucrose density gradient centrifugation patterns of ribosomes was analyzed for both laboratory strains of Escherichia coli and natural isolates from the ECOR collection. All of the natural isolates examined formed 100S ribosome dimers in the stationary phase, and ribosome modulation factor (RMF) was associated with the ribosome dimers in the ECOR strains as in the laboratory strain W3110. The ribosome profile (70S monomers versus 100S dimers) follows a defined pattern over time during lengthy culture in both the laboratory strains and natural isolates. There are four discrete stages: (i) formation of 100S dimers in the early stationary phase; (ii) transient decrease in the dimer level; (iii) return of dimers to the maximum level; and (iv) dissociation of 100S dimers into 70S ribosomes, which are quickly degraded into subassemblies. The total time for this cycle of ribosome profile change, however, varied from strain to strain, resulting in apparent differences in the ribosome profiles when observed at a fixed time point. A correlation was noted in all strains between the decay of 100S ribosomes and the subsequent loss of cell viability. Two types of E. coli mutants defective in ribosome dimerization were identified, both of which were unable to survive for a prolonged period in stationary phase. The W3110 mutant, with a disrupted rmf gene, has a defect in ribosome dimerization because of lack of RMF, while strain Q13 is unable to form ribosome dimers due to a ribosomal defect in binding RMF. PMID:10781560

Wada, Akira; Mikkola, Riitta; Kurland, Charles G.; Ishihama, Akira

2000-01-01

440

Laboratory evaluation of natural pyrethrins, pymetrozine and triflumuron as alternatives to control Ceratitis capitata adults  

Microsoft Academic Search

Three insecticides, pyrethrins + piperonil butoxide (PBO), pymetrozine and triflumuron, were tested as potential alternatives\\u000a for controlling the Mediterranean fruit flyCeratitis capitata (Wiedemann) (Diptera: Tephritidae). The compounds were administered to adult flies in the laboratory by different uptake\\u000a methods at the recommended rates currently used in fruit crops in Spain. Pyrethrins + PBO (80 + 320 ppm a.i.) exhibited a

Nelson Zapata; Flor Budia; Elisa Vifiuela; Pilar Medina

2006-01-01

441

Investigating the genetics of Bti resistance using mRNA tag sequencing: application on laboratory strains and natural populations of the dengue vector Aedes aegypti  

PubMed Central

Mosquito control is often the main method used to reduce mosquito-transmitted diseases. In order to investigate the genetic basis of resistance to the bio-insecticide Bacillus thuringiensis subsp. israelensis (Bti), we used information on polymorphism obtained from cDNA tag sequences from pooled larvae of laboratory Bti-resistant and susceptible Aedes aegypti mosquito strains to identify and analyse 1520 single nucleotide polymorphisms (SNPs). Of the 372 SNPs tested, 99.2% were validated using DNA Illumina GoldenGate® array, with a strong correlation between the allelic frequencies inferred from the pooled and individual data (r = 0.85). A total of 11 genomic regions and five candidate genes were detected using a genome scan approach. One of these candidate genes showed significant departures from neutrality in the resistant strain at sequence level. Six natural populations from Martinique Island were sequenced for the 372 tested SNPs with a high transferability (87%), and association mapping analyses detected 14 loci associated with Bti resistance, including one located in a putative receptor for Cry11 toxins. Three of these loci were also significantly differentiated between the laboratory strains, suggesting that most of the genes associated with resistance might differ between the two environments. It also suggests that common selected regions might harbour key genes for Bti resistance. PMID:24187584

Paris, Margot; Marcombe, Sebastien; Coissac, Eric; Corbel, Vincent; David, Jean-Philippe; Després, Laurence

2013-01-01

442

Investigating the genetics of Bti resistance using mRNA tag sequencing: application on laboratory strains and natural populations of the dengue vector Aedes aegypti.  

PubMed

Mosquito control is often the main method used to reduce mosquito-transmitted diseases. In order to investigate the genetic basis of resistance to the bio-insecticide Bacillus thuringiensis subsp. israelensis (Bti), we used information on polymorphism obtained from cDNA tag sequences from pooled larvae of laboratory Bti-resistant and susceptible Aedes aegypti mosquito strains to identify and analyse 1520 single nucleotide polymorphisms (SNPs). Of the 372 SNPs tested, 99.2% were validated using DNA Illumina GoldenGate® array, with a strong correlation between the allelic frequencies inferred from the pooled and individual data (r = 0.85). A total of 11 genomic regions and five candidate genes were detected using a genome scan approach. One of these candidate genes showed significant departures from neutrality in the resistant strain at sequence level. Six natural populations from Martinique Island were sequenced for the 372 tested SNPs with a high transferability (87%), and association mapping analyses detected 14 loci associated with Bti resistance, including one located in a putative receptor for Cry11 toxins. Three of these loci were also significantly differentiated between the laboratory strains, suggesting that most of the genes associated with resistance might differ between the two environments. It also suggests that common selected regions might harbour key genes for Bti resistance. PMID:24187584

Paris, Margot; Marcombe, Sebastien; Coissac, Eric; Corbel, Vincent; David, Jean-Philippe; Després, Laurence

2013-11-01

443

Salience: the key to the selection problem in natural language generation  

SciTech Connect

The authors argue that in domains where a strong notion of salience can be defined, it can be used to provide: (1) an elegant solution to the selection problem, i.e. the problem of how to decide whether a given fact should or should not be mentioned in the text; and (2) a simple and direct control framework for the entire deep generation process, coordinating proposing, planning, and realization. (Deep generation involves reasoning about conceptual and rhetorical facts, as opposed to the narrowly linguistic reasoning that takes place during realization.) The authors report on an empirical study of salience in pictures of natural scenes, and its use in a computer program that generates descriptive paragraphs comparable to those produced by people. 13 references.

Conklin, E.J.; McDonald, D.D.

1982-01-01

444

THE zCOSMOS-SINFONI PROJECT. I. SAMPLE SELECTION AND NATURAL-SEEING OBSERVATIONS  

SciTech Connect

The zCOSMOS-SINFONI project is aimed at studying the physical and kinematical properties of a sample of massive z {approx} 1.4-2.5 star-forming galaxies, through SINFONI near-infrared integral field spectroscopy (IFS), combined with the multiwavelength information from the zCOSMOS (COSMOS) survey. The project is based on one hour of natural-seeing observations per target, and adaptive optics (AO) follow-up for a major part of the sample, which includes 30 galaxies selected from the zCOSMOS/VIMOS spectroscopic survey. This first paper presents the sample selection, and the global physical characterization of the target galaxies from multicolor photometry, i.e., star formation rate (SFR), stellar mass, age, etc. The H{alpha} integrated properties, such as, flux, velocity dispersion, and size, are derived from the natural-seeing observations, while the follow-up AO observations will be presented in the next paper of this series. Our sample appears to be well representative of star-forming galaxies at z {approx} 2, covering a wide range in mass and SFR. The H{alpha} integrated properties of the 25 H{alpha} detected galaxies are similar to those of other IFS samples at the same redshifts. Good agreement is found among the SFRs derived from H{alpha} luminosity and other diagnostic methods, provided the extinction affecting the H{alpha} luminosity is about twice that affecting the continuum. A preliminary kinematic analysis, based on the maximum observed velocity difference across the source and on the integrated velocity dispersion, indicates that the sample splits nearly 50-50 into rotation-dominated and velocity-dispersion-dominated galaxies, in good agreement with previous surveys.

Mancini, C.; Renzini, A. [INAF-OAPD, Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, I-35122 Padova (Italy); Foerster Schreiber, N. M.; Hicks, E. K. S.; Genzel, R.; Tacconi, L.; Davies, R. [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Cresci, G. [Osservatorio Astrofisico di Arcetri (OAF), INAF-Firenze, Largo E. Fermi 5, I-50125 Firenze (Italy); Peng, Y.; Lilly, S.; Carollo, M.; Oesch, P. [Institute of Astronomy, Department of Physics, Eidgenossische Technische Hochschule, ETH Zurich CH-8093 (Switzerland); Vergani, D.; Pozzetti, L.; Zamorani, G. [INAF-Bologna, Via Ranzani, I-40127 Bologna (Italy); Daddi, E. [CEA-Saclay, DSM/DAPNIA/Service d'Astrophysique, F-91191 Gif-Sur Yvette Cedex (France); Maraston, C. [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, PO1 3HE Portsmouth (United Kingdom); McCracken, H. J. [IAP, 98bis bd Arago, F-75014 Paris (France); Bouche, N. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Shapiro, K. [Aerospace Research Laboratories, Northrop Grumman Aerospace Systems, Redondo Beach, CA 90278 (United States); and others

2011-12-10

445

INTEGR. COMP. BIOL., 45:391404 (2005) How and When Selection Experiments Might Actually be Useful1  

E-print Network

, Florida 32306-4340 SYNOPSIS. Laboratory natural selection and artificial selection are vital tools for addressing specific ques- tions about evolutionary patterns of variation. Laboratory natural selection can the two types of selection experiments and clar- ify our definition of ``complex traits.'' Next, we de

Fuller, Rebecca

446

Development of resistance to eCry3.1Ab-expressing transgenic maize in a laboratory-selected population of western corn rootworm (Coleoptera: Chrysomelidae)  

Technology Transfer Automated Retrieval System (TEKTRAN)

A laboratory colony of western corn rootworm, Diabrotica virgifera virgifera LeConte, was selected for resistance to transgenic maize expressing the eCry3.1ab protein. The selected colony was developed by rearing larvae on non-elite, non-commercial Bt maize expressing the eCry3.1Ab protein. After ...

447

University of Florida Natural Area Teaching Laboratory 2013 NATL Minigrant Program  

E-print Network

Ecological Enhancement Project (SEEP) is an ecologically enhanced 3- acre retention pond in UF's Natural Area drains (Figure 1). These diverse inputs require the SEEP to treat pollution in the form of nutrients project would assess the spatial variability of nitrate in the SEEP basin: inputs from stormwater drains

Slatton, Clint

448

2009-10 Minigrant Program for UF's Natural Area Teaching Laboratory  

E-print Network

for teaching or research. · Update the list of vascular plants that occur in SEEP and integrate it with what-contouring], in 1999 [after planting], and in 2004 [the 5-year census] (see http://natl.ifas.ufl.edu/plants.htm#SEEP). · Prepare two or more 3x2-ft interpretative panels for the west leg of the SEEP nature trail. (Stands

Slatton, Clint

449

Out of the Laboratory: Teaching about the History and Nature of Science and Technology.  

ERIC Educational Resources Information Center

Identifies and discusses six themes for teaching "History and Nature of Science and Technology" developed by a teacher enhancement workshop. The themes are designed to provide instructional guidelines for teachers developing courses in this area. Includes sample project descriptions, learning outcomes, and instructional activities. (MJP)

Singleton, Laurel R.

1997-01-01

450

Effects of Novel Isoform-Selective Phosphoinositide 3-Kinase Inhibitors on Natural Killer Cell Function  

PubMed Central

Phosphoinositide 3-kinases (PI3Ks) are promising targets for therapeutic development in cancer. The class I PI3K isoform p110? has received considerable attention in oncology because the gene encoding p110? (PIK3CA) is frequently mutated in human cancer. However, little is known about the function of p110? in lymphocyte populations that modulate tumorigenesis. We used recently developed investigational inhibitors to compare the function of p110? and other isoforms in natural killer (NK) cells, a key cell type for immunosurveillance and tumor immunotherapy. Inhibitors of all class I isoforms (pan-PI3K) significantly impaired NK cell-mediated cytotoxicity and antibody-dependent cellular cytotoxicity against tumor cells, whereas p110?-selective inhibitors had no effect. In NK cells stimulated through NKG2D, p110? inhibition modestly reduced PI3K signaling output as measured by AKT phosphorylation. Production of IFN-? and NK cell-derived chemokines was blocked by a pan-PI3K inhibitor and partially reduced by a p110?inhibitor, with lesser effects of p110? inhibitors. Oral administration of mice with MLN1117, a p110? inhibitor in oncology clinical trials, had negligible effects on NK subset maturation or terminal subset commitment. Collectively, these results support the targeting of PIK3CA mutant tumors with selective p110? inhibitors to preserve NK cell function. PMID:24915189

Yea, Sung Su; So, Lomon; Mallya, Sharmila; Lee, Jongdae; Rajasekaran, Kamalakannan; Malarkannan, Subramaniam; Fruman, David A.

2014-01-01

451

Natural Selection Canalizes Expression Variation of Environmentally Induced Plasticity-Enabling Genes  

PubMed Central

Many organisms survive fluctuating and extreme environmental conditions by manifesting multiple distinct phenotypes during adulthood by means of developmental processes that enable phenotypic plasticity. We report on the discovery of putative plasticity-enabling genes that are involved in transforming the gill of the euryhaline teleost fish, Fundulus heteroclitus, from its freshwater to its seawater gill-type, a process that alters both morphology and function. Gene expression that normally enables osmotic plasticity is inhibited by arsenic. Gene sets defined by antagonistic interactions between arsenic and salinity show reduced transcriptional variation among individual fish, suggesting unusually accurate and precise regulatory control of these genes, consistent with the hypothesis that they participate in a canalized developmental response. We observe that natural selection acts to preserve canalized gene expression in populations of killifish that are most tolerant to abrupt salinity change and that these populations show the least variability in their transcription of genes enabling plasticity of the gill. We found that genes participating in this highly canalized and conserved plasticity-enabling response had significantly fewer and less complex associations with transcriptional regulators than genes that respond only to arsenic or salinity. Collectively these findings, which are drawn from the relationships between environmental challenge, plasticity, and canalization among populations, suggest that the selective processes that facilitate phenotypic plasticity do so by targeting the regulatory networks that gives rise to the response. These findings also provide a generalized, conceptual framework of how genes might interact with the environment and evolve toward the development of plastic traits. PMID:25158801

Shaw, Joseph R.; Hampton, Thomas H.; King, Benjamin L.; Whitehead, Andrew; Galvez, Fernando; Gross, Robert H.; Keith, Nathan; Notch, Emily; Jung, Dawoon; Glaholt, Stephen P.; Chen, Celia Y.; Colbourne, John K.; Stanton, Bruce A.

2014-01-01

452

Periodic Table of Virus Capsids: Implications for Natural Selection and Design  

PubMed Central

Background For survival, most natural viruses depend upon the existence of spherical capsids: protective shells of various sizes composed of protein subunits. So far, general evolutionary pressures shaping capsid design have remained elusive, even though an understanding of such properties may help in rationally impeding the virus life cycle and designing efficient nano-assemblies. Principal Findings This report uncovers an unprecedented and species-independent evolutionary pressure on virus capsids, based on the the notion that the simplest capsid designs (or those capsids with the lowest “hexamer complexity”, ) are the fittest, which was shown to be true for all available virus capsids. The theories result in a physically meaningful periodic table of virus capsids that uncovers strong and overarching evolutionary pressures, while also offering geometric explanations to other capsid properties (rigidity, pleomorphy, auxiliary requirements, etc.) that were previously considered to be unrelatable properties of the individual virus. Significance Apart from describing a universal rule for virus capsid evolution, our work (especially the periodic table) provides a language with which highly diverse virus capsids, unified only by geometry, may be described and related to each other. Finally, the available virus structure databases and other published data reiterate the predicted geometry-derived rules, reinforcing the role of geometry in the natural selection and design of virus capsids. PMID:20209096

Mannige, Ranjan V.; Brooks, Charles L.

2010-01-01

453

Hydrolytic stability of helical RNA: a selective advantage for the natural 3',5'-bond.  

PubMed Central

Dodecaadenylic acid containing a single 2', 5'-linkage at a defined position was formed by the coupling of two hexamers on a poly(U) template at 2 degrees. The rate of hydrolysis of this dodecamer was compared with that of a dodecamer that contained only the natural 3', 5'-linkages. At 40 degrees, in 1 M aqueous ethylenediamine at pH 8 in the absence of poly(U), both dodecamers hydrolyzed at comparable rates, but the addition of two equivalents of poly(U) caused a 7-fold increase in the initial rate of hydrolysis of the oligomer containing the 2', 5'-bond, and a 5-fold decrease in the initial rate of hydrolysis of the natural oligomer. When the oligomers are fully constrained in helical form, the ratio of the rates of cleavage of one 2', 5'-bond to one 3', 5'-bond under these conditions is probably about 900:1. The use of the 3', 5'-bond, in combination with a right-handed helix, appears to have had a large selective advantage over the use of the 2', 5'-bond for the storage of genetic information. PMID:1063396

Usher, D A; McHale, A H

1976-01-01

454

Preliminary delineation of natural geochemical reactions, Snake River Plain aquifer system, Idaho National Engineering Laboratory and vicinity, Idaho  

SciTech Connect

The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, is conducting a study to determine the natural geochemistry of the Snake River Plain aquifer system at the Idaho National Engineering Laboratory (INEL), Idaho. As part of this study, a group of geochemical reactions that partially control the natural chemistry of ground water at the INEL were identified. Mineralogy of the aquifer matrix was determined using X-ray diffraction and thin-section analysis and theoretical stabilities of the minerals were used to identify potential solid-phase reactants and products of the reactions. The reactants and products that have an important contribution to the natural geochemistry include labradorite, olivine, pyroxene, smectite, calcite, ferric oxyhydroxide, and several silica phases. To further identify the reactions, analyses of 22 representative water samples from sites tapping the Snake River Plain aquifer system were used to determine the thermodynamic condition of the ground water relative to the minerals in the framework of the aquifer system. Principal reactions modifying the natural geochemical system include congruent dissolution of olivine, diopside, amorphous silica, and anhydrite; incongruent dissolution of labradorite with calcium montmorillonite as a residual product; precipitation of calcite and ferric oxyhydroxide; and oxidation of ferrous iron to ferric iron. Cation exchange reactions retard the downward movement of heavy, multivalent waste constituents where infiltration ponds are used for waste disposal.

Knobel, L.L.; Bartholomay, R.C.; Orr, B.R.

1997-05-01

455

Mineralogy of selected sedimentary interbeds at or near the Idaho National Engineering Laboratory, Idaho  

SciTech Connect

The US Geological Survey`s (USGS) Project Office at the Idaho National Engineering Laboratory (INEL) analyzed 66 samples from sedimentary interbed cores during a 38-month period beginning in October 1990 to determine bulk and clay mineralogy. These cores had been collected from 19 sites in the Big Lost River Basin, 2 sites in the Birch Creek Basin, and 1 site in the Mud Lake Basin, and were archived at the USGS lithologic core library at the INEL. Mineralogy data indicate that core samples from the Big Lost River Basin have larger mean and median percentages of quartz, total feldspar, and total clay minerals, but smaller mean and median percentages of calcite than the core samples from the Birch Creek Basin. Core samples from the Mud Lake Basin have abundant quartz, total feldspar, calcite, and total clay minerals. Identification of the mineralogy of the Snake River Plain is needed to aid in the study of the hydrology and geochemistry of subsurface waste disposal.

Reed, M.F.; Bartholomay, R.C.

1994-08-01

456

Evaluation of Macroinvertebrate Communities and Habitat for Selected Stream Reaches at Los Alamos National Laboratory  

SciTech Connect

This is the second aquatic biological monitoring report generated by Los Alamos National Laboratory's (LANL's) Water Quality and Hydrology Group. The study has been conducted to generate impact-based assessments of habitat and water quality for LANL waterways. The monitoring program was designed to allow for the detection of spatial and temporal trends in water and habitat quality through ongoing, biannual monitoring of habitat characteristics and benthic aquatic macroinvertebrate communities at six key sites in Los Alamos, Sandia, Water, Pajarito, and Starmer's Gulch Canyons. Data were collected on aquatic habitat characteristics, channel substrate, and macroinvertebrate communities during 2001 and 2002. Aquatic habitat scores were stable between 2001 and 2002 at all locations except Starmer's Gulch and Pajarito Canyon, which had lower scores in 2002 due to low flow conditions. Channel substrate changes were most evident at the upper Los Alamos and Pajarito study reaches. The macroinvertebrate Stream Condition Index (SCI) indicated moderate to severe impairment at upper Los Alamos Canyon, slight to moderate impairment at upper Sandia Canyon, and little or no impairment at lower Sandia Canyon, Starmer's Gulch, and Pajarito Canyon. Habitat, substrate, and macroinvertebrate data from the site in upper Los Alamos Canyon indicated severe impacts from the Cerro Grande Fire of 2000. Impairment in the macroinvertebrate community at upper Sandia Canyon was probably due to effluent-dominated flow at that site. The minimal impairment SCI scores for the lower Sandia site indicated that water quality improved with distance downstream from the outfall at upper Sandia Canyon.

L.J. Henne; K.J. Buckley

2005-08-12

457

Algal food selection and digestion by larvae of the pestiferous chironomid Chironomus Crassicaudatus under laboratory conditions.  

PubMed

Feeding preference of Chironomus crassicaudatus 4th instars when fed on 5 algal species, Anabaena flos-aquae, Botryococcus braunii, Lyngbia cf. aeruginosa, Microcystis sp., and Scenedesmus quadricauda was studied under laboratory conditions. The various algal species were mixed in pairs at 1:1 ratio (fresh weight) to create 10 possible test combinations. The larvae were allowed to feed individually for 8 h on each algal mixture in tissue culture plates having 4 replicates. Four identical algal mixtures were simultaneously used without larvae as controls. After feeding, larvae and excrement were removed, and remaining algae from feeding trials and controls were fixed with Lugol's solution; the final ratio of algal species in each mixture was determined microscopically. Feeding preferences of C. crassicaudatus early 4th instars, in descending order, was L. cf. aeruginosa, A. flos-aquae, B. braunii, Microcystis sp., and S. quadricaudata. To evaluate algal digestibility, larval excrement was collected and the proportion of live and dead cells was determined by microscopic observations with the use of visible and ultraviolet light (epifluorescence). Anabaena flos-aquae and L. cf. aeruginosa were the easiest to digest, followed by Microcystis sp. and S. quadricaudata, whereas no digestion of B. braunii was observed. Cultures of larval excrement revealed the presence of some viable cells of all 5 tested algal species. PMID:15669393

Frouz, Jan; Ali, Arshad; Lobinske, Richard J

2004-12-01

458

The application of natural zeolites for mercury removal: from laboratory tests to industrial scale  

Microsoft Academic Search

The paper discusses the application of natural zeolites from clinoptilolite group for mercury removal from industrial effluents from copper smelter and refinery. The experiments included studies on sorption mechanisms (adsorption or ion-exchange) and sorption equilibria. The dominating mechanism of sorption with zeolite was found to be ion exchange and the maximum sorption capacity was evaluated as 1.21 meq\\/g sorbent. Three

A. Chojnacki; K. Chojnacka; J. Hoffmann; H. Górecki

2004-01-01

459

High Fitness of Heterokaryotypic Individuals Segregating Naturally within a Long-Standing Laboratory Population of Drosophila silvestris.  

PubMed

Natural populations of Drosophila silvestris are polymorphic for inversions in one or more of four of the five major chromosome arms; laboratory stocks tend to retain this heterozygosity. A laboratory stock, U28T2, was started from a single naturally inseminated wild female caught at Kilauea Forest Reserve, Hawaii, in January 1977. Polytene analysis in 1980 showed the presence of three natural inversions in chromosome 4: k( 2) is distal, t is central and l(2) is proximal. The inversions are short but only short uncovered euchromatic sections exist at the distal and proximal ends. Periodic examinations through 1986 showed all three inversions to be persistent at moderately high frequencies. In 1984, a series of tests of mating performance of caged, mature males, taken at random as they eclosed from the stock, were followed by cytological testcrosses to females from a homokaryotypic stock. Only three of the eight possible haplotypes, k(2)/t/+ (A), +/+/l(2) ( a) and +/+/+ (a') were present. Tests of crossing over show none in males; in females, there is about 1% in each of the two regions between the inversions. Only one such apparent crossover haplotype was found among 1084 examined in samples from this stock. Thus, chromosome arrangements A, a and a' virtually behave as wholechromosome alleles in both sexes. Of 146 males marked and tested in cages, 61 produced progeny; the others failed to reproduce. Of 58 males and 80 females producing progeny and analyzed cytologically, there were, respectively, 49 and 59 heterokaryotypes. On the basis of frequencies calculated for fertilized eggs, 33.6 males and 46.3 females are expected. The facts suggest that individual males with the Aa karyotype are particularly successful in production of offspring. Adult females show an excess of Aa' as well as Aa. Such high fitness of heterokaryotypes in the effective breeding adults could be a major factor in the maintenance of stable chromosomal polymorphisms both in laboratory stocks and in nature. Although some of this heterosis is clearly ascribable to differential survival, the facts suggest that there is a substantial opportunity, indeed a likelihood, for a contribution from differential mating among surviving adults. PMID:17246392

Carson, H L

1987-07-01

460

Mars-GRAM Applications for Mars Science Laboratory Mission Site Selection Processes  

NASA Technical Reports Server (NTRS)

An overview is presented of the Mars-Global Reference Atmospheric Model (Mars-GRAM 2005) and its new features. One important new feature is the "auxiliary profile" option, whereby a simple input file is used to replace mean atmospheric values from Mars-GRAM's conventional (General Circulation Model) climatology. An auxiliary profile can be generated from any source of data or alternate model output. Results are presented using auxiliary profiles produced from mesoscale model output (Southwest Research Institute's Mars Regional Atmospheric Modeling System (MRAMS) model and Oregon State University's Mars mesoscale model (MMM5) model) for three candidate Mars Science Laboratory (MSL) landing sites (Terby Crater, Melas Chasma, and Gale Crater). A global Thermal Emission Spectrometer (TES) database has also been generated for purposes of making 'Mars-GRAM auxiliary profiles. This data base contains averages and standard deviations of temperature, density, and thermal wind components, averaged over 5-by-5 degree latitude bins and 15 degree L(sub S) bins, for each of three Mars years of TES nadir data. Comparisons show reasonably good consistency between Mars-GRAM with low dust optical depth and both TES observed and mesoscale model simulated density at the three study sites. Mean winds differ by a more significant degree. Comparisons of mesoscale and TES standard deviations' with conventional Mars-GRAM values, show that Mars-GRAM density perturbations are somewhat conservative (larger than observed variability), while mesoscale-modeled wind variations are larger than Mars-GRAM model estimates. Input parameters rpscale (for density perturbations) and rwscale (for wind perturbations) can be used to "recalibrate" Mars-GRAM perturbation magnitudes to better replicate observed or mesoscale model variability.

Justh, Hilary; Justus, C. G.

2007-01-01

461

Did RNA editing in plant organellar genomes originate under natural selection or through genetic drift?  

PubMed Central

Background The C?U substitution types of RNA editing have been observed frequently in organellar genomes of land plants. Although various attempts have been made to explain why such a seemingly inefficient genetic mechanism would have evolved, no satisfactory explanation exists in our view. In this study, we examined editing patterns in chloroplast genomes of the hornwort Anthoceros formosae and the fern Adiantum capillus-veneris and in mitochondrial genomes of the angiosperms Arabidopsis thaliana, Beta vulgaris and Oryza sativa, to gain an understanding of the question of how RNA editing originated. Results We found that 1) most editing sites were distributed at the 2nd and 1st codon positions, 2) editing affected codons that resulted in larger hydrophobicity and molecular size changes much more frequently than those with little change involved, 3) editing uniformly increased protein hydrophobicity, 4) editing occurred more frequently in ancestrally T-rich sequences, which were more abundant in genes encoding membrane-bound proteins with many hydrophobic amino acids than in genes encoding soluble proteins, and 5) editing occurred most often in genes found to be under strong selective constraint. Conclusion These analyses show that editing mostly affects functionally important and evolutionarily conserved codon positions, codons and genes encoding membrane-bound proteins. In particular, abundance of RNA editing in plant organellar genomes may be associated with disproportionately large percentages of genes in these two genomes that encode membrane-bound proteins, which are rich in hydrophobic amino acids and selectively constrained. These data support a hypothesis that natural selection imposed by protein functional constraints has contributed to selective fixation of certain editing sites and maintenance of the editing activity in plant organelles over a period of more than four hundred millions years. The retention of genes encoding RNA editing activity may be driven by forces that shape nucleotide composition equilibrium in two organellar genomes of these plants. Nevertheless, the causes of lineage-specific occurrence of a large portion of RNA editing sites remain to be determined. Reviewers This article was reviewed by Michael Gray (nominated by Laurence Hurst), Kirsten Krause (nominated by Martin Lercher), and Jeffery Mower (nominated by David Ardell). PMID:18939975

Jobson, Richard W; Qiu, Yin-Long

2008-01-01

462

Selection of indigenous isolates of entomopathogenic soil fungus Metarhizium anisopliae under laboratory conditions.  

PubMed

Eight native isolates of the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin were obtained by monitoring soils cultivated in a conventional manner. These isolates were compared in three areas: (a) conidial germination, (b) radial growth and sporulation and (c) ability of conidia to infect Tenebrio molitor larvae. All bioassays were carried out at constant temperatures of 10, 15, and 20 °C. Conidia of individual isolates demonstrated differences in germination after a 24-h long incubation at all evaluated temperatures. At 20 °C, the germination ranged from 67 to 100 % and at 15 °C from 5.33 to 46.67 %. At 10 °C, no germination was observed after 24 h; nevertheless, it was 8.67-44.67 % after 48 h. In terms of radial growth, the culture diameters and the associated production of spores of all isolates increased with increasing temperature. At 10 °C, sporulation was observed in three isolates while all remaining cultures appeared sterile. Three weeks post-inoculation, conidia of all assessed isolates caused 100 % cumulative mortality of treated larvae of T. molitor at 15 and 20 °C with the exception of isolate 110108 that induced 81.33 % mortality at 15 °C. At 10 °C, larval cumulative mortality ranged from 6.67 to 85.33 % depending on the isolate. Isolates 110108 and 110111 showed significantly slower outset and a much lower rate of infection at all temperatures compared to other tested isolates of M. anisopliae. The bioassays were carried out with the purpose to sort and select indigenous isolates of M. anisopliae useful as biocontrol agents in their original habitat. PMID:24338078

Skalický, Aleš; Bohatá, Andrea; Šimková, Jana; Osborne, Lance S; Landa, Zden?k

2014-07-01

463

Natural Selection on Coding and Noncoding DNA Sequences Is Associated with Virulence Genes in a Plant Pathogenic Fungus  

PubMed Central

Natural selection leaves imprints on DNA, offering the opportunity to identify functionally important regions of the genome. Identifying the genomic regions affected by natural selection within pathogens can aid in the pursuit of effective strategies to control diseases. In this study, we analyzed genome-wide patterns of selection acting on different classes of sequences in a worldwide sample of eight strains of the model plant-pathogenic fungus Colletotrichum graminicola. We found evidence of selective sweeps, balancing selection, and positive selection affecting both protein-coding and noncoding DNA of pathogenicity-related sequences. Genes encoding putative effector proteins and secondary metabolite biosynthetic enzymes show evidence of positive selection acting on the coding sequence, consistent with an Arms Race model of evolution. The 5? untranslated regions (UTRs) of genes coding for effector proteins and genes upregulated during infection show an excess of high-frequency polymorphisms likely the consequence of balancing selection and consistent with the Red Queen hypothesis of evolution acting on these putative regulatory sequences. Based on the findings of this work, we propose that even though adaptive substitutions on coding sequences are important for proteins that interact directly with the host, polymorphisms in the regulatory sequences may confer flexibility of gene expression in the virulence processes of this important plant pathogen. PMID:25193312

Rech, Gabriel E.; Sanz-Martín, José M.; Anisimova, Maria; Sukno, Serenella A.; Thon, Michael R.

2014-01-01

464

How does selection operate on whole-organism functional performance capacities? A review and synthesis  

Microsoft Academic Search

Hypothesis: Natural and sexual selection should be stronger on whole-organism functional performance traits (sprinting, biting) than on correlated morphological variables. Organisms: Lizards, snakes, turtles, frogs, and fish (review of past field and laboratory studies). Field sites: Various (review of past field and laboratory studies). Methods: We reviewed existing literature on the nature and intensity of natural and sexual selection on

Duncan J. Irschick; Jerry J. Meyers; Jerry F. Husak; Jean-François Le Galliard

2008-01-01

465

Unravelling floods selection mechanisms for vegetation from laboratory experiments and implications for river restoration efficiency  

NASA Astrophysics Data System (ADS)

The establishment and evolution of vegetation in organized patterns on river bar alluvial sediment are active morphodynamic processes governed by flow hydrology. Although this is well documented in literature, how do time scales between the arrival of flow disturbances and vegetation growth interact to determine the survival of certain vegetation characteristics is still unclear. We started to explore such dynamics within the research project RIVERINE (RIver - VEgetation interactions and Reproduction of Island Nuclei formation and Evolution), funded by the Hydralab III European Framework Programme. Laboratory experiments are important tools which allow comprehensive observations of the feedbacks between flow, channel morphology and vegetation, which are otherwise difficult to observe at the real scale. In this work we present the results of novel flume experiments that we carried out at the Total Environment Simulator (TES) of the University of Hull, United Kingdom. Starting from an initial levelled slope of 1%, the channel was seeded with Avena Sativa at a uniform density. A number of days after seeding, the flume was flooded daily for 4 days with a flood disturbance which lasted 15 minutes. Different flood magnitudes as well as times between seeding and the first disturbance and flume geometries (i.e., parallel and convergent walls) were investigated. After each disturbance the eroded material (sediment, seeds and plants) was collected at the channel bottom and corresponding statistics for main root length, number of roots and stem height were calculated. At the same time, random samples of non-eroded plants were sampled from the flume and the same statistics were computed for a control run. After every flood disturbance, the channel bed surface was measured with a laser scanner and photographed. Since flooding frequencies were comparable with the plant root germination and growth time scales, vegetation and flood disturbances were in direct competition. Results show that while non-eroded plants continue to grow in successive runs, flow erosion acts preferentially on plants that have a weaker root system. In particular, a direct linkage between flow magnitude and the first statistical moment of the distribution of the eroded plants seems not to depend on successive runs as long as the distributions of the eroded and the non-eroded plants overlap. Channel geometry influences specific stream power, which in turn would affect the limit where colonization by vegetation in a converging channel is successful. Although the collected data at present have an explorative value only, our findings can be useful for river restoration practice. We show that the timescale of flood disturbance and that of root growth interact in determining whether a particular vegetation species can be successful in the colonization of a given river system. Moreover, the analysis of the influence of channel shape can be useful to identify the best location for plant establishment.

Perucca, Eliana; Molnar, Peter; Francis, Robert; Perona, Paolo

2010-05-01

466

Evidence for divergent natural selection of a Lake Tanganyika cichlid inferred from repeated radiations in body size.  

PubMed

Divergent natural selection is thought to play a vital role in speciation, but clear, measurable examples from nature are still few. Among the many possible sources of divergent natural selection, predation pressure may be important because predators are ubiquitous in food webs. Here, we show evidence for divergent natural selection in a Lake Tanganyika cichlid, Telmatochromis temporalis, which uses burrows under stones or empty snail shells as shelters. This species contains normal and dwarf morphs at several localities. The normal morph inhabits rocky shorelines, whereas the dwarf morph invariably inhabits shell beds, where empty snail shells densely cover the lake bottom. Genetic evidence suggested that the dwarf morph evolved independently from the normal morph at two areas, and morphological analysis and evaluation of habitat structure revealed that the body sizes of morphs closely matched the available shelter sizes in their habitats. These findings suggest that the two morphs repeatedly evolved through divergent natural selection associated with the strategy for sheltering from predators. PMID:19549109

Takahashi, T; Watanabe, K; Munehara, H; Rüber, L; Hori, M

2009-07-01

467

Evaluation of Cavity Collapse and Surface Crater Formation for Selected Lawrence Livermore National Laboratory Underground Nuclear Tests - 2010  

SciTech Connect

This report evaluates collapse evolution for selected Lawrence Livermore National Laboratory (LLNL) underground nuclear tests at the Nevada National Security Site (NNSS, formerly called the Nevada Test Site). The work is being done at the request of Navarro-Interra LLC, and supports environmental restoration efforts by the Department of Energy, National Nuclear Security Administration for the Nevada Site Office. Safety decisions must be made before a surface crater area, or potential surface crater area, can be reentered for any work. Our statements on cavity collapse and surface crater formation are input into their safety decisions. These statements do not include the effects of erosion that may modify the surface collapse craters over time. They also do not address possible radiation dangers that may be present. Subject matter experts from the LLNL Containment Program who had been active in weapons testing activities performed these evaluations. Information used included drilling and hole construction, emplacement and stemming, timing and sequence of the selected test and nearby tests, geology, yield, depth of burial, collapse times, surface crater sizes, cavity and crater volume estimations, and ground motion. Both classified and unclassified data were reviewed. Various amounts of information are available for these tests, depending on their age and other associated activities. Lack of data can hamper evaluations and introduce uncertainty. We make no attempt to quantify this uncertainty.

Pawloski, G A

2011-01-03

468

Evaluation of Cavity Collapse and Surface Crater Formation for Selected Lawrence Livermore National Laboratory Underground Nuclear Tests - 2011, Part 2  

SciTech Connect

This report evaluates collapse evolution for selected Lawrence Livermore National Laboratory (LLNL) underground nuclear tests at the Nevada National Security Site (NNSS, formerly called the Nevada Test Site).