Sample records for laboratory natural selection

  1. Directional versus Stabilizing Selection for Developmental Time in Natural and Laboratory Populations of Flour Beetles

    PubMed Central

    Dawson, Peter S.

    1975-01-01

    Artificial selection for fast development is successful in long-established laboratory populations of Tribolium, but not in strains recently derived from natural populations. It is shown that selection against fast development in dense, synchronized cultures operates through cannibalism of early pupae by larvae. Since standard husbandry procedures for laboratory strains involve the periodic creation of dense, synchronized cultures, it is suggested that these populations are subjected to stabilizing selection for intermediate developmental time. Natural populations, on the other hand, are probably subjected to directional selection for rapid development. PMID:17248688

  2. Demonstrating Natural Selection

    ERIC Educational Resources Information Center

    Hinds, David S.; Amundson, John C.

    1975-01-01

    Describes laboratory exercises with chickens selecting their food from dyed and natural corn kernels as a method of demonstrating natural selection. The procedure is based on the fact that organisms that blend into their surroundings escape predation. (BR)

  3. natural selection

    NSDL National Science Digital Library

    David Joiner

    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.

  4. A Natural Selection: Partnering Teachers and Scientists in the Classroom Laboratory Creates a Dynamic Learning Community

    ERIC Educational Resources Information Center

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

    2005-01-01

    The high school science laboratory provides a natural environment for students to learn through scientist-teacher partnerships. Scientists represent an excellent resource for teachers and students: They possess specialized knowledge and skills, have access to laboratory equipment and materials, and are immersed in a culture of collaborative…

  5. Natural Selection

    NSDL National Science Digital Library

    Heather Thiel-Cobbey

    2012-01-01

    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.

  6. A Natural Selection

    NSDL National Science Digital Library

    Katherine M. Nielsen

    2005-10-01

    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.

  7. Natural Selection

    NSDL National Science Digital Library

    Werner Heim

    2007-12-12

    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.

  8. Addressing Undergraduate Student Misconceptions about Natural Selection with an Interactive Simulated Laboratory

    Microsoft Academic Search

    Joel K. Abraham; Eli Meir; Judy Perry; Jon C. Herron; Susan Maruca; Derek Stal

    2009-01-01

    Although evolutionary theory is considered to be a unifying foundation for biological education, misconceptions about basic\\u000a evolutionary processes such as natural selection inhibit student understanding. Even after instruction, students harbor misconceptions\\u000a about natural selection, suggesting that traditional teaching methods are insufficient for correcting these confusions. This\\u000a has spurred an effort to develop new teaching methods and tools that effectively confront

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

    PubMed Central

    Glorieux, Cédric; Cuguen, Joel; Roux, Fabrice

    2012-01-01

    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

  10. THE NATURE AND EXTENT OF LABORATORY INSTRUCTION IN SELECTED MODERN HIGH SCHOOL BIOLOGY CLASSES.

    ERIC Educational Resources Information Center

    BARNES, LEHMAN WILDER, JR.

    ANALYZED WAS THE RELATIONSHIP BETWEEN THE DEGREE TO WHICH LABORATORY ACTIVITIES CONFORMED TO LABORATORY ACTIVITIES RECOMMENDED BY BIOLOGICAL SCIENCES CURRICULUM STUDY (BSCS) AND THREE SPECIFIC VARIABLES WHICH WERE (1) AVAILABLE LABORATORY FACILITIES, (2) ACCEPTANCE OF BSCS OBJECTIVES, AND (3) CLASS GAIN IN THE UNDERSTANDING OF SCIENCE. DATA WERE…

  11. Natural Selection and Natural Theology

    Microsoft Academic Search

    Asa Gray

    1883-01-01

    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.

  12. Laboratory Activities to Support Student Understanding of the Molecular Mechanisms of Mutation & Natural Selection

    ERIC Educational Resources Information Center

    Hubler, Tina; Adams, Patti; Scammell, Jonathan

    2015-01-01

    The molecular basis of evolution is an important and challenging concept for students to understand. In a previous article, we provided some of the scientific background necessary to teach this topic. This article features a series of laboratory activities demonstrating that molecular events can alter the genomes of organisms. These activities are…

  13. Natural Selection and Natural Theology

    Microsoft Academic Search

    J. B. Hannay

    1883-01-01

    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

  14. Evolution by Natural Selection

    NSDL National Science Digital Library

    Jennifer Doherty

    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.

  15. Visualizingandquantifying natural selection

    E-print Network

    Brodie III, Edmund D.

    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

  16. The Pretorious fault, Mponeng mine, South Africa: A site selected for the establishment of a natural earthquake laboratory

    NASA Astrophysics Data System (ADS)

    Reches, Z.; van Aswegen, G.; Jordan, T. H.; Johnston, M.; Zoback, M.

    2004-12-01

    One major obstacle in earthquake investigations is the lack of direct and near-field observations. To reduce this limitation, we initiated the NELSAM project (Natural Earthquake Laboratory in South African Mines) for in-situ seismic observations at 3.5 km depth (session S11 this meeting). The project includes instrumentation of the complete frequency range (creepmeters, seismometers, strain meters, accelerometers, temperature sensors, acoustic emission transducers). This dense 3D array is designed to monitor fault activity before, during, and after M = 2.5-3.5 earthquakes at distances of 1-100 m from their anticipated hypocenters. The site characterization will include 3D mapping, in-situ stress measurements on local and regional scales, and rock mechanics analysis. We describe here the structural and seismic features of the first site where monitoring is planned to start circa April, 2005.We screened and ranked 12 active faults in South African mines according to dimensions, internal structure, accessibility, and likelihood of M 3.0 seismic events. The selected site is on the Pretorius fault, one of the largest faults in the Western Deep Levels gold mines, WSW of Johannesburg. This fault-zone is at least 10 km long; it is very steep and inclined toward the SSE with throw up to 70 m. It contains many individual fault surfaces that vary in inclination from 40 deg to vertical; some have thin breccia zones with quartz cementation, and a few display a fine-grain gouge, but there is no major, well-developed gouge zone. The Pretorius fault accommodated some amount of strike-slip displacement as indicated by frequent inversion of the sense of fault throw, the occurrence of horizontal slickenside striations, and its steepness. The Pretorius fault-zone was active in Archaean times, and it has been locally reactivated by the mining operations in Mponeng and Tautona mines, which provide access to depths of 3.0-3.5 km. Our monitoring site will be established where both sides of the Pretorius fault will be mined during the next few years; the practice in the deep mines and numerical modeling predict profound increase of the seismic activity at the site during the next 2-4 years. The associated increase of shear stresses on the fault is expected to generate a few earthquakes of M>3.0 along surfaces of hundreds to thousands of sq. meters within the fault zone. Monitoring the fault zone activity and particularly the larger events is the main objective of NELSAM.

  17. Natural Selection Lesson

    NSDL National Science Digital Library

    David Joiner

    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.

  18. 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.

  19. Introduction to Natural Selection

    NSDL National Science Digital Library

    This lesson will help students develop an understanding of natural selection, specifically, how it unfolds from generation to generation. The Motivation section introduces a species of bird that became (over millions of years) numerous species, through adaptation. The Development section is a hands-on activity that demonstrates how populations change little by little, generation by generation, due to survival of species that have traits that are beneficial in an environment. Students will learn why organisms evolve over time, how natural selection works, and how certain factors determine survival and differences in organisms.

  20. Reinventing Natural Selection

    ERIC Educational Resources Information Center

    Geraedts, Caspar L.; Boersma, Kerst Th.

    2006-01-01

    Although many research studies report students' Lamarckian misconceptions, only a few studies present learning and teaching strategies that focus on the successful development of the concept of natural selection. The learning and teaching strategy for upper secondary students (aged 15-16) presented in this study conducted in The Netherlands is…

  1. Investigating Natural Selection

    NSDL National Science Digital Library

    In this activity, students experience one mechanism for evolution through a simulation that models the principles of natural selection and helps answer the question 'how might biological change have occurred and been reinforced over time?' Students will discover that species evolve over time and evolution is the consequence of the interaction of the potential for a species to increase in number, the genetic variability of offspring due to mutation and recombination of genes, a finite supply of the resources required for life, and the ensuing selection of those offspring better able to survive and leave offspring in a particular environment. Natural selection and its evolutionary consequences provide a scientific explanation for the fossil record of ancient life forms, as well as for the striking molecular similarities observed among the diverse species of living organisms. The site also contains a list of materials and all information and instructions required to complete this activity.

  2. Introduction to Natural Selection

    NSDL National Science Digital Library

    Science Netlinks

    2002-03-28

    This lesson is an introduction to natural selection and is suited to any student who is just beginning his or her discovery of evolution. The motivation introduces a species of bird that became (over millions of years) numerous species, through adaptation. The development is a hands-on activity that demonstrates how populations change little by little, generation by generation, due to survival of species that have traits that are beneficial in an environment.

  3. Naturally selecting solutions

    PubMed Central

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

    2013-01-01

    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

  4. Extending cosmological natural selection

    E-print Network

    Gordon McCabe

    2009-08-31

    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.

  5. Natural Selection Simulation

    NSDL National Science Digital Library

    2012-05-29

    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.

  6. Natural Selection and Natural Theology

    Microsoft Academic Search

    Asa Gray

    1883-01-01

    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.

  7. Natural Selection and Natural Theology

    Microsoft Academic Search

    Asa Gray

    1883-01-01

    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

  8. Natural Selection and Natural Theology

    Microsoft Academic Search

    George J. Romanes

    1883-01-01

    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

  9. Natural Selection and Geology 230

    E-print Network

    Kammer, Thomas

    ;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

  10. Molecular Signatures of Natural Selection

    E-print Network

    Nielsen, Rasmus

    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

  11. Visualizing and quantifying natural selection

    Microsoft Academic Search

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

    1995-01-01

    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

  12. Modeling Natural Selection

    ERIC Educational Resources Information Center

    Bogiages, Christopher A.; Lotter, Christine

    2011-01-01

    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 better understanding of the content, process, and nature of science (Kenyon, Schwarz, and Hug…

  13. Investigating Natural Selection: Elementary School

    NSDL National Science Digital Library

    2010-01-01

    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.

  14. On cosmic natural selection

    E-print Network

    Alexander Vilenkin

    2006-11-27

    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.

  15. Evolution Through Natural Selection

    NSDL National Science Digital Library

    Tim Comar (Benedictine University; Mathematics)

    2005-04-17

    This workbook simulates the population genetics of a single gene with two alleles, allowing the user to set the initial allele frequencies and enter parameters for a variety of different selection models; the program then tracks the population through up to 10,000 generations.

  16. Charles Darwin II: Natural selection

    NSDL National Science Digital Library

    Alfred Rosenberger

    2004-02-12

    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.

  17. Natural selection on gene expression

    Microsoft Academic Search

    Yoav Gilad; Alicia Oshlack; Scott A. Rifkin

    2006-01-01

    Changes in genetic regulation contribute to adaptations in natural populations and influence susceptibility to human diseases. Despite their potential phenotypic importance, the selective pressures acting on regulatory processes in general and gene expression levels in particular are largely unknown. Studies in model organisms suggest that the expression levels of most genes evolve under stabilizing selection, although a few are consistent

  18. Natural Selection: How Evolution Works

    NSDL National Science Digital Library

    Douglas Futuyma (State University of New York at Stony Brook; )

    2004-12-01

    The issue-focused interview demonstrates how natural selection is a very efficient, predictable mechanism of evolution. It illustrates how species adapt to their environment, the reproductive success of a species, design in nature and presents evidence of evolution in action, e.g., antibiotic resistance.

  19. The cost of natural selection

    Microsoft Academic Search

    J. B. S. Haldane

    1957-01-01

    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

  20. Friendship and natural selection

    PubMed Central

    Christakis, Nicholas A.; Fowler, James H.

    2014-01-01

    More than any other species, humans form social ties to individuals who are neither kin nor mates, and these ties tend to be with similar people. Here, we show that this similarity extends to genotypes. Across the whole genome, friends’ genotypes at the single nucleotide polymorphism level tend to be positively correlated (homophilic). In fact, the increase in similarity relative to strangers is at the level of fourth cousins. However, certain genotypes are also negatively correlated (heterophilic) in friends. And the degree of correlation in genotypes can be used to create a “friendship score” that predicts the existence of friendship ties in a hold-out sample. A focused gene-set analysis indicates that some of the overall correlation in genotypes can be explained by specific systems; for example, an olfactory gene set is homophilic and an immune system gene set is heterophilic, suggesting that these systems may play a role in the formation or maintenance of friendship ties. Friends may be a kind of “functional kin.” Finally, homophilic genotypes exhibit significantly higher measures of positive selection, suggesting that, on average, they may yield a synergistic fitness advantage that has been helping to drive recent human evolution. PMID:25024208

  1. Laboratory Selection Quickly Erases Historical Differentiation

    PubMed Central

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

    2014-01-01

    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

  2. Natural Selection in the Brain

    Microsoft Academic Search

    Chrisantha Fernando; Eörs Szathmáry

    \\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

  3. Natural Selection and Applied Genetics

    NSDL National Science Digital Library

    2010-01-01

    Natural Selection and Applied Genetics is a graduate-level professional development course designed to enhance your understanding and teaching of life science. In two sessions, you will investigate life science topics using hands-on activities and online resources including video segments, interactive activities, readings, and other multimedia materials. These resources are drawn from Teachers' Domain, WGBH's digital library service.

  4. Darwin's Finches and Natural Selection

    NSDL National Science Digital Library

    Cheryl A. Heinz

    2008-01-01

    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.

  5. Scavenger Hunt: Simulating Natural Selection

    NSDL National Science Digital Library

    This kinesthetic activity simulates the process of evolution by natural selection. Students take on the roles of crab-like predators that exhibit one of four variants of feeding appendage: a spoon, fork, knife, and chopsticks. The simulation runs for three trials, as the predators use their appendages to harvest pinto beans, with varying success. Students track the frequency of each appendage type through three generations. This resource is from PUMAS - Practical Uses of Math and Science - a collection of brief examples created by scientists and engineers showing how math and science topics taught in K-12 classes have real world applications.

  6. Natural selection and population Ilik Saccheri1

    E-print Network

    Trexler, Joel C.

    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

  7. Non-random Allelic Variation Natural Selection

    E-print Network

    Houde, Peter

    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

  8. 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

  9. Lab 2: Natural selection Basic instructions

    E-print Network

    Nuismer, Scott L.

    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

  10. Simulate Natural Selection With Beetles

    NSDL National Science Digital Library

    In this simulation activity, students experiment with a population of M&M candies or paper dot "beetles" to test how well each color is adapted to survive on a field of colorful wrapping paper or fabric. Students act as predators and see that camouflaged beetles survive predation preferentially. Students reflect on how the activity could be modified to better simulate the process of predation-based natural selection. This activity is supported by a textbook chapter, "Origin of Species," part of the unit, "Losing Biodiversity," in Global Systems Science (GSS), an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.

  11. Natural Selection Because of Different Color: Camouflage

    NSDL National Science Digital Library

    Dave Cavanagh

    2012-11-14

    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.

  12. Natural Selection: Exploring Variation and Heritability

    NSDL National Science Digital Library

    This lesson has students think about two important components of Darwin's model of natural selection in greater detail. First, they will have an opportunity to explore the natural variations present in a variety of organisms. Specifically, they will examine sunflower seeds and Wisconsin Fast Plants. Next, they will use data and graphs of that data from an artificial selection experiment to consider the role of heredity in natural selection. They will answer questions related to a graph and review the statistical concepts of mean, median, mode, and range and will work in groups to examine and answer questions about graphs. The site includes instructional notes for the teacher and the required student handouts.

  13. Method for route selection of transcontinental natural gas pipelines

    E-print Network

    Kouroupetroglou, Georgios

    1 Method for route selection of transcontinental natural gas pipelines Fotios G. Thomaidis1.U. energy corridor 1. Introduction Route selection of transcontinental natural gas pipelines route selection method The route selection method for transcontinental natural gas pipelines results

  14. Natural resource economics: Selected papers

    SciTech Connect

    Ciriacy-Wantrup, S.V.

    1985-01-01

    This volume was assembled by two of Dr. Wantrup's students as a complement to his textbook, Resource Conservation: Economics and Policies. Wantrup's ideas on conservation economics continued to evolve in ways that were never fully reflected in the textbook and, although for the student of natural resource economics it is still essential reading, to stop there is to have missed some of his most valuable insights. Part 1 of this book deals with various aspects of the ''commons'' problem and includes Wantrup's key contributions to the literature on ''common property,'' which he brought to its current place of prominence in natural resource economics. Parts 2 and 3 focus on water-related issues; Part 4 looks at recent writings in the conservation area, with particular emphasis on irreversibility and uncertainty; and the final section examines the role of natural resources in economic development. Each part is introduced by one of Wantrup's students, and their special insights help guide the reader toward the most significant of Wantrup's ideas.

  15. Experiencing Natural Selection: Will You Survive?

    NSDL National Science Digital Library

    2012-06-11

    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.

  16. LABORATORY #9 --BIOL 111 Natural Selection

    E-print Network

    , there should be: - 50 small white beans (Navy beans) - 50 large white beans (Lima beans) - 50 medium red beans two species: a predator (you) and prey (bean species). Every table will become a battleground between) and 200 prey (different beans). In each round, you will "eat" beans by collecting them into your "stomach

  17. 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.

  18. The negative view of natural selection.

    PubMed

    Birch, Jonathan

    2012-06-01

    An influential argument due to Elliott Sober, subsequently strengthened by Denis Walsh and Joel Pust, moves from plausible premises to the bold conclusion that natural selection cannot explain the traits of individual organisms. If the argument were sound, the explanatory scope of selection would depend, surprisingly, on metaphysical considerations concerning origin essentialism. I show that the Sober-Walsh-Pust argument rests on a flawed counterfactual criterion for explanatory relevance. I further show that a more defensible criterion for explanatory relevance recently proposed by Michael Strevens lends support to the view that natural selection can be relevant to the explanation of individual traits. PMID:22520205

  19. The Natural Selection of Stick-Worms

    NSDL National Science Digital Library

    Don Dutton

    This lesson teaches students that traits are usually favored by natural selection only when they result in more reproductively successful offspring. Students go out onto the school lawn and play the role of birds, picking up toothpick stick worms which have been previously scattered in equal numbers of green-stained and unstained. Birds are chased away before the worm population drops too low. Back in the classroom, the number of green and non-green worms are compared individually and for the whole class. Discussion relates the experience to the elements of natural selection. As presented here, it does not lend itself to demonstrating the effects of selection over multiple generations.

  20. Comparing Patterns of Natural Selection across Species Using Selective Signatures

    SciTech Connect

    Shapiro, Jesse; Alm, Eric J.

    2007-12-01

    Comparing gene expression profiles over many different conditions has led to insights that were not obvious from single experiments. In the same way, comparing patterns of natural selection across a set of ecologically distinct species may extend what can be learned from individual genome-wide surveys. Toward this end, we show how variation in protein evolutionary rates, after correcting for genome-wide effects such as mutation rate and demographic factors, can be used to estimate the level and types of natural selection acting on genes across different species. We identify unusually rapidly and slowly evolving genes, relative to empirically derived genome-wide and gene family-specific background rates for 744 core protein families in 30 c-proteobacterial species. We describe the pattern of fast or slow evolution across species as the"selective signature" of a gene. Selective signatures represent aprofile of selection across species that is predictive of gene function: pairs of genes with correlated selective signatures are more likely to share the same cellular function, and genes in the same pathway can evolve in concert. For example,glycolysis and phenylalanine metabolism genes evolve rapidly in Idiomarina loihiensis, mirroring an ecological shift in carbon source from sugars to amino acids. In a broader context, our results suggest that the genomic landscape is organized into functional modules even at the level of natural selection, and thus it may be easier than expected to understand the complex evolutionary pressures on a cell.

  1. Comparing Patterns of Natural Selection Across Species Using Selective Signatures

    SciTech Connect

    Alm, Eric J.; Shapiro, B. Jesse; Alm, Eric J.

    2007-12-18

    Comparing gene expression profiles over many different conditions has led to insights that were not obvious from single experiments. In the same way, comparing patterns of natural selection across a set of ecologically distinct species may extend what can be learned from individual genome-wide surveys. Toward this end, we show how variation in protein evolutionary rates, after correcting for genome-wide effects such as mutation rate and demographic factors, can be used to estimate the level and types of natural selection acting on genes across different species. We identify unusually rapidly and slowly evolving genes, relative to empirically derived genome-wide and gene family-specific background rates for 744 core protein families in 30 gamma-proteobacterial species. We describe the pattern of fast or slow evolution across species as the 'selective signature' of a gene. Selective signatures represent a profile of selection across species that is predictive of gene function: pairs of genes with correlated selective signatures are more likely to share the same cellular function, and genes in the same pathway can evolve in concert. For example, glycolysis and phenylalanine metabolism genes evolve rapidly in Idiomarina loihiensis, mirroring an ecological shift in carbon source from sugars to amino acids. In a broader context, our results suggest that the genomic landscape is organized into functional modules even at the level of natural selection, and thus it may be easier than expected to understand the complex evolutionary pressures on a cell.

  2. Summer Field Assistant (Two positions) Natural Resource Ecology Laboratory

    E-print Network

    Summer Field Assistant (Two positions) Natural Resource Ecology Laboratory Colorado State University The Natural Resource Ecology Laboratory is seeking two seasonal field assistants to support forest, Ecology, or Natural Resource Management. Experience in backpacking, GIS, GPS and/or orienteering, forest

  3. Natural and sexual selection against hybrid flycatchers

    PubMed Central

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

    2008-01-01

    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

  4. Natural and Sexual Selection on Many Loci

    PubMed Central

    Barton, N. H.; Turelli, M.

    1991-01-01

    A method is developed that describes the effects on an arbitrary number of autosomal loci of selection on haploid and diploid stages, of nonrandom mating between haploid individuals, and of recombination. We provide exact recursions for the dynamics of allele frequencies and linkage disequilibria (nonrandom associations of alleles across loci). When selection is weak relative to recombination, our recursions provide simple approximations for the linkage disequilibria among arbitrary combinations of loci. We show how previous models of sex-independent natural selection on diploids, assortative mating between haploids, and sexual selection on haploids can be analyzed in this framework. Using our weak-selection approximations, we derive new results concerning the coevolution of male traits and female preferences under natural and sexual selection. In particular, we provide general expressions for the intensity of linkage-disequilibrium induced selection experienced by loci that contribute to female preferences for specific male traits. Our general results support the previous observation that these indirect selection forces are so weak that they are unlikely to dominate the evolution of preference-producing loci. PMID:2016044

  5. Clippy Island: An Investigation into Natural Selection

    NSDL National Science Digital Library

    Lauren Furness

    2012-04-09

    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.

  6. Natural selection. IV. The Price equation*

    PubMed Central

    Frank, Steven A.

    2012-01-01

    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

  7. The Natural Selection of Bean Hunters

    NSDL National Science Digital Library

    This lesson on natural selection shows students that population characteristics can change as a result of selective pressures operating over several generations. In the lesson, groups of students go hunting for beans in the lawn. Each group has a different tool (e.g. hand, spoon, fork, etc). There are three different colors of beans. The hunting goes for three rounds (generations), with extinctions and reproduction occurring between rounds.

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

    E-print Network

    Richerson, Peter J.

    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

  9. Sir Wyville Thomson and Natural Selection

    Microsoft Academic Search

    Charles Darwin

    1880-01-01

    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

  10. The status of cosmological natural selection

    Microsoft Academic Search

    Lee Smolin

    2006-01-01

    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

  11. A Lesson on Evolution & Natural Selection

    ERIC Educational Resources Information Center

    Curtis, Anthony D.

    2010-01-01

    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…

  12. Ocean waves, nearshore ecology, and natural selection

    Microsoft Academic Search

    Mark W. Denny

    2006-01-01

    Although they are subjected to one of the most stressful physical environments on earth, wave-swept rocky shores support a highly diverse community of plants and animals. The surprising presence of such diversity amidst severe environmental adversity provides a unique opportunity for exploration of the role of extreme water flows in community ecology and natural selection. Methods are described by which

  13. Leprosy and the natural selection for psoriasis

    Microsoft Academic Search

    Ioannis D. Bassukas; Georgios Gaitanis; Max Hundeiker

    Psoriasis is a genetically determined, almost worldwide-distributed inflammatory skin disease with overall higher prevalence among people of northern European ancestry. Since enhanced innate immunity is an important feature of the pathophysiology of this disease, it has been proposed that differences in the prevalence of psoriasis in different populations mainly result from differences in natural selection for gene polymorphisms associated with

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

    PubMed

    Ayala, Francisco J

    2010-08-01

    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

  15. A Selected Bibliography on Microbiological Laboratory Design.

    ERIC Educational Resources Information Center

    Laboratory Design Notes, 1967

    1967-01-01

    Reference sources on microbiological laboratory design are cited. Subjects covered include--(1) policies and general requirements, (2) ventilated cabinets, (3) animal isolation equipment, (4) air handling, ventilation, and filtration, (5) germicidal ultraviolet irradiation, (6) aerosol test facilities, (7) process production of microorganisms, and…

  16. Laboratory evaluation of selected tar sand asphalts

    SciTech Connect

    Button, J.W.; Epps, J.A.; Gallaway, B.M.

    1980-12-01

    Three tar sand asphalts of similar grades prepared from one syncrude by three different refining methods were characterized by tests commonly used to specify paving asphalts together with certain special tests. Asphalt-aggregate mixtures were prepared using these asphalts and tested in the laboratory to determine strength stiffness stability, tensile properties, temperature effects and water susceptibility. Comparison of the tar sand asphalt properties to conventional petroleum asphalt properties reveal no striking differences.

  17. Investigating Natural Selection: Middle and High School

    NSDL National Science Digital Library

    2010-01-01

    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.

  18. Natural Selection: Introduction to Darwin's Model

    NSDL National Science Digital Library

    This information will introduce students to Darwin's model of natural selection in the same way that they learned about Paley and Lamarck. First, they will read an excerpt from Origin of Species and answer questions about it. Then, they will have an opportunity to consider the example of artificial selection (like pigeons or dogs) and think about how this process relates to Darwin's argument. Finally, students will spend time working in groups, thinking about Darwin's prior knowledge and beliefs. This site also contains instructional notes for the teacher and the required worksheets for the students.

  19. Darwinian natural selection: its enduring explanatory power

    PubMed Central

    2012-01-01

    Evolutionary theory has never had a stronger scientific foundation than it does today. In a short review I hope to portray the deep commitment of today's biologists to Darwinian natural selection and to discoveries made since Darwin's time. In spite of the scientific advances in the century and a half since the publication of On the Origin of Species, Darwin still remains the principal author of modern evolutionary theory. He is one of the greatest contributors of all time to our understanding of nature. PMID:22481845

  20. The status of cosmological natural selection

    E-print Network

    Lee Smolin

    2006-12-18

    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.

  1. The Structure of Evolution by Natural Selection

    Microsoft Academic Search

    Richmond Campbell; Jason Scott Robert

    2005-01-01

    We attempt a conclusive resolution of the debate over whether the principle of natural selection (PNS), especially conceived\\u000a as the `principle' of the `survival of the fittest', is a tautology. This debate has been largely ignored for the past 15 years\\u000a but not, we think, because it has actually been settled. We begin by describing the tautology objection, and situating the

  2. Fisher's fundamental theorem of natural selection.

    PubMed

    Frank, S A; Slatkin, M

    1992-03-01

    Fisher's Fundamental Theorem of natural selection is one of the most widely cited theories in evolutionary biology. Yet it has been argued that the standard interpretation of the theorem is very different from what Fisher meant to say. What Fisher really meant can be illustrated by looking in a new way at a recent model for the evolution of clutch size. Why Fisher was misunderstood depends, in part, on the contrasting views of evolution promoted by Fisher and Wright. PMID:21235964

  3. Natural Selection of Antibiotic Resistant Bacteria

    NSDL National Science Digital Library

    Dave Cavanagh

    2012-06-26

    In this activity (p.3-4 of PDF), learners learn about disease transmission and antibiotic resistance. In this activity, an educator shows what could happen if one learner has not washed his/her hands properly before lunch and becomes ill as a result. The educator uses beans to illustrate both disease transmission and the development of antibiotic resistant bacteria. Use this activity to discuss the importance of proper hygiene, disease transmission, and both natural and artificial selection.

  4. Symbiogenesis, natural selection, and the dynamic Earth.

    PubMed

    Kutschera, U

    2009-08-01

    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

  5. Natural and sexual selection in a monogamous historical human population

    E-print Network

    Lummaa, Virpi

    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

  6. Alloprocoptic selection: A mode of natural selection promoting polymorphism

    PubMed Central

    Serradilla, Juan M.; Ayala, Francisco J.

    1983-01-01

    The fitness effect of genetic variation at three loci coding for enzymes is studied in Drosophila melanogaster. The fertility of a female is determined by the female genotype as well as by the genotype of the male with which she mates. Significant interactions exist between female and male genotype, so that the fertility of a given mating combination cannot be predicted from the average fertility of the two genotypes involved. Multiple stable equilibria are possible when such interactions exist. At two loci, the fertility is greater than expected when the two mating individuals are homozygous for different alleles and smaller than expected when they are homozygous for the same allele. This mode of selection in which association of opposites increases their fitness is herein named alloprocoptic selection. It will contribute to maintaining genetic polymorphism in nature. PMID:16593303

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

    ERIC Educational Resources Information Center

    Eason, Perri K.; Sherman, Peter T.

    2003-01-01

    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…

  8. Sexual and Natural Selection Both Influence Male Genital Evolution

    PubMed Central

    Hodgson, Dave J.; Wedell, Nina; Sharma, Manmohan D.; Hunt, John; Hosken, David J.

    2013-01-01

    Rapid and divergent evolution of male genital morphology is a conspicuous and general pattern across internally fertilizing animals. Rapid genital evolution is thought to be the result of sexual selection, and the role of natural selection in genital evolution remains controversial. However, natural and sexual selection are believed to act antagonistically on male genital form. We conducted an experimental evolution study to investigate the combined effects of natural and sexual selection on the genital-arch lobes of male Drosophila simulans. Replicate populations were forced to evolve under lifetime monogamy (relaxed sexual selection) or lifetime polyandry (elevated sexual selection) and two temperature regimes, 25°C (relaxed natural selection) or 27°C (elevated natural selection) in a fully factorial design. We found that natural and sexual selection plus their interaction caused genital evolution. Natural selection caused some aspects of genital form to evolve away from their sexually selected shape, whereas natural and sexual selection operated in the same direction for other shape components. Additionally, sexual and natural selection tended to favour larger genitals. Thus we find that the underlying selection driving genital evolution is complex, does not only involve sexual selection, and that natural selection and sexual selection do not always act antagonistically. PMID:23717488

  9. Darwin's finches: population variation and natural selection.

    PubMed Central

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

    1976-01-01

    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

  10. Natural Selection: Developing a Darwinian Explanation

    NSDL National Science Digital Library

    This lesson asks students to take their understanding of Darwin's model of natural selection and begin to think about how it can be used to explain natural phenomena. They will do this by first attempting individually to explain the case of lizard camouflage to provide a concrete example from which to work. Next, they will work within their groups to compile an explanation based on all of their work and, finally, they will be asked to develop a set of criteria for acceptable explanations. Each individual student will develop a Darwinian explanation and each group will write a complete explanation and a list of criteria for a good explanation. The site includes instructional notes for teachers and a student handout.

  11. Natural Selection: Monarch/Viceroy Case

    NSDL National Science Digital Library

    This lesson will provide students with an opportunity to use their understanding of the natural selection model to explain phenomena. For this case they will be asked to account for the bright coloration of and the similarity between monarch and viceroy butterflies. In order to do this, they will work in groups to develop a Darwinian explanation using the narrative structure developed in previous material. Each group will receive a folder with information on species that exhibit a particularly interesting biological phenomenon. The materials in the folders will include narrative descriptions of the organisms and their natural history, pictures, and data tables or graphs to help understand the biology of the characteristics under study. Groups will then present their ideas to their peers and discuss the different explanations in a round table forum. The site also includes detailed instructional notes for the teachers and all of the student handouts required for the folders.

  12. The inductive theory of natural selection

    E-print Network

    Frank, Steven A

    2014-01-01

    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.

  13. Natural Image Statistics and Low-Complexity Feature Selection

    E-print Network

    Vasconcelos, Nuno M.

    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

  14. Using Card Games to Simulate the Process of Natural Selection

    ERIC Educational Resources Information Center

    Grilliot, Matthew E.; Harden, Siegfried

    2014-01-01

    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…

  15. Research article Measuring natural selection on proportional traits

    E-print Network

    Stinchcombe, John

    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

  16. ORIGINAL PAPER Interactions between sexual and natural selection

    E-print Network

    Walters, Jeffrey R.

    ORIGINAL PAPER Interactions between sexual and natural selection on the evolution of a plumage and natural selection. A tidal-marsh sparrow, Melospiza georgiana nigrescens, possesses darker pigmentation natural selection on badge evolution. Across both subspecies the extent of rusty feathers in the cap patch

  17. Implications of the Reduction Principle for Cosmological Natural Selection

    E-print Network

    Altenberg, Lee

    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

  18. Microbiological study of selected risk areas in dental technology laboratories

    Microsoft Academic Search

    J. Verran; S. Kossar; J. F. McCord

    1996-01-01

    Objectives: To investigate the microbiological status of certain risk areas in the dental technology laboratory, namely pumice slurry, impression agar and curing water baths.Methods: Samples were inoculated onto selective and non-selective media. Resultant fungal and bacterial colonies were counted and identified to genus or species level.Results: Pumice slurry freshly made up using disinfectant was free from contamination, but colony counts

  19. 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

    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

    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

  20. 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

    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

    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.

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

    E-print Network

    King, Richard B.

    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

  2. Los Alamos National Laboratory selects three small businesses for

    E-print Network

    - 1 - Los Alamos National Laboratory selects three small businesses for environmental work May 14, 2013 Value of up to $150 million over five years LOS ALAMOS, N.M., May 14, 2013--Los Alamos National Nuclear Security Administration's Los Alamos Field Office Environmental Projects Office. The current

  3. Natural Selection: Comparison of the Models

    NSDL National Science Digital Library

    This lesson provides an opportunity for students to extend their understanding of the three models studied in previous lessons by using them to explain phenomena and by comparing them to one another. Students will work in groups to use the models of Paley, Lamarck, and Darwin to explain the origin of complex structures like the eye, the existence of fossils, and the variety of pigeon breeds. They will confer with another group to share ideas and participate in a class discussion comparing the models and develop written explanations for phenomena based on their understanding of the three models. This lesson represents a turning point in the unit as students conclude their examination of the ideas of Paley and Lamarck and prepare for a more in-depth study of Darwin's model of natural selection. The site also includes instructional notes for teachers and the required student handouts.

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

    Microsoft Academic Search

    B. S. Baldwin

    1995-01-01

    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

  5. Reproduction of natural corrosion by accelerated laboratory testing methods

    SciTech Connect

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

    1996-05-01

    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.

  6. 164 nature physics | VOL 5 | MARCH 2009 | www.nature.com/naturephysics A quantum of natural selection

    E-print Network

    Loss, Daniel

    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

  7. The snowmaker: nature identical snow production in the laboratory

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  8. Selective phonotaxis of female crickets under natural outdoor conditions.

    PubMed

    Hirtenlehner, Stefan; Römer, Heiner

    2014-03-01

    Acoustic mate choice in insects has been extensively studied under laboratory conditions, using different behavioural paradigms. Ideally, however, mate choice designs should reflect natural conditions, including the physical properties of the transmission channel for the signal. Since little is known about the discrimination ability of females between male song variants under natural conditions, we performed phonotaxis experiments with female field crickets (Gryllus bimaculatus) outdoors, using two-choice decisions based on differences in carrier frequency, sound pressure level, and chirp rate. For all three song parameters, minimum differences necessary for a significant preference between two song models were considerably larger outdoors compared to laboratory conditions. A minimum amplitude difference of 5 dB was required for a significant choice in the field, compared to only 1-2 dB reported for lab-based experiments. Due to the tuned receiver system, differences in carrier frequency equal differences in perceived loudness, and the results on choice for differences in carrier frequency corroborate those in amplitude. Similarly, chirp rate differences of 50 chirps/min were required outdoors compared to only 20 chirps/min in the lab. For predictions about patterns of sexual selection, future studies need to consider the different outcomes of mate choice decisions in lab and field trials. PMID:24488017

  9. NATURAL SELECTION ON COLOR PATTERNS IN POECILIA RETICULATA

    Microsoft Academic Search

    JOHN A. ENDLER

    1980-01-01

    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

  10. Microbial Resistance to Triclosan: A Case Study in Natural Selection

    ERIC Educational Resources Information Center

    Serafini, Amanda; Matthews, Dorothy M.

    2009-01-01

    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…

  11. A Working Model of Natural Selection Illustrated by Table Tennis

    ERIC Educational Resources Information Center

    Dinc, Muhittin; Kilic, Selda; Aladag, Caner

    2013-01-01

    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

  12. The Nature of Laboratory Learning Experiences in Secondary Science Online

    ERIC Educational Resources Information Center

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

    2013-01-01

    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…

  13. Good genes sexual selection in nature

    PubMed Central

    Byers, John A.; Waits, Lisette

    2006-01-01

    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

  14. Good genes sexual selection in nature.

    PubMed

    Byers, John A; Waits, Lisette

    2006-10-31

    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

  15. Patterns and Power of Phenotypic Selection in Nature

    NSDL National Science Digital Library

    Joel G. Kingsolver, David W. Pfennig (; )

    2007-07-01

    This article from the July/August 2007 issue of BioScience is about natural selection and quantifies the strength of selection in nature. Phenotypic selection occurs when individuals with certain characteristics produce more surviving offspring than individuals with other characteristics. Although selection is regarded as the chief engine of evolutionary change, scientists have only recently begun to measure its action in the wild. These studies raise numerous questions: How strong is selection, and do different types of traits experience different patterns of selection? Is selection on traits that affect mating success as strong as selection on traits that affect survival? Does selection tend to favor larger body size, and, if so, what are its consequences? We explore these questions and discuss the pitfalls and future prospects of measuring selection in natural populations.

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

    PubMed

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

    2013-11-01

    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

  17. NATURAL RESOURCE MANAGEMENT PLAN FOR BROOKHAVEN NATIONAL LABORATORY.

    SciTech Connect

    GREEN,T.ET AL.

    2003-12-31

    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.

  18. SELECTIVE NOx RECIRCULATION FOR STATIONARY LEAN-BURN NATURAL GAS ENGINES

    Microsoft Academic Search

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

    2005-01-01

    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

  19. Sexual selection and natural selection in bird speciation

    PubMed Central

    Price, T.

    1998-01-01

    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.

  20. BSL-3 laboratory practices in the United States: comparison of select agent and non-select agent facilities.

    PubMed

    Richards, Stephanie L; Pompei, Victoria C; Anderson, Alice

    2014-01-01

    New construction of biosafety level 3 (BSL-3) laboratories in the United States has increased in the past decade to facilitate research on potential bioterrorism agents. The Centers for Disease Control and Prevention inspect BSL-3 facilities and review commissioning documentation, but no single agency has oversight over all BSL-3 facilities. This article explores the extent to which standard operating procedures in US BSL-3 facilities vary between laboratories with select agent or non-select agent status. Comparisons are made for the following variables: personnel training, decontamination, personal protective equipment (PPE), medical surveillance, security access, laboratory structure and maintenance, funding, and pest management. Facilities working with select agents had more complex training programs and decontamination procedures than non-select agent facilities. Personnel working in select agent laboratories were likely to use powered air purifying respirators, while non-select agent laboratories primarily used N95 respirators. More rigorous medical surveillance was carried out in select agent workers (although not required by the select agent program) and a higher level of restrictive access to laboratories was found. Most select agent and non-select agent laboratories reported adequate structural integrity in facilities; however, differences were observed in personnel perception of funding for repairs. Pest management was carried out by select agent personnel more frequently than non-select agent personnel. Our findings support the need to promote high quality biosafety training and standard operating procedures in both select agent and non-select agent laboratories to improve occupational health and safety. PMID:24552359

  1. BSL-3 Laboratory Practices in the United States: Comparison of Select Agent and Non–Select Agent Facilities

    PubMed Central

    Pompei, Victoria C.; Anderson, Alice

    2014-01-01

    New construction of biosafety level 3 (BSL-3) laboratories in the United States has increased in the past decade to facilitate research on potential bioterrorism agents. The Centers for Disease Control and Prevention inspect BSL-3 facilities and review commissioning documentation, but no single agency has oversight over all BSL-3 facilities. This article explores the extent to which standard operating procedures in US BSL-3 facilities vary between laboratories with select agent or non–select agent status. Comparisons are made for the following variables: personnel training, decontamination, personal protective equipment (PPE), medical surveillance, security access, laboratory structure and maintenance, funding, and pest management. Facilities working with select agents had more complex training programs and decontamination procedures than non–select agent facilities. Personnel working in select agent laboratories were likely to use powered air purifying respirators, while non–select agent laboratories primarily used N95 respirators. More rigorous medical surveillance was carried out in select agent workers (although not required by the select agent program) and a higher level of restrictive access to laboratories was found. Most select agent and non–select agent laboratories reported adequate structural integrity in facilities; however, differences were observed in personnel perception of funding for repairs. Pest management was carried out by select agent personnel more frequently than non–select agent personnel. Our findings support the need to promote high quality biosafety training and standard operating procedures in both select agent and non–select agent laboratories to improve occupational health and safety. PMID:24552359

  2. Using the FAR Guide to Teach Simulations: An Example with Natural Selection

    ERIC Educational Resources Information Center

    Sickel, Aaron J.; Friedrichsen, Patricia J.

    2012-01-01

    Engaging students in a predator-prey simulation to teach natural selection is a common activity in secondary biology classrooms. The purpose of this article is to demonstrate how the authors have changed their approach to teaching this activity from a laboratory investigation to a class-constructed simulation. Specifically, the authors drew upon a…

  3. Seal formation in arid soil under natural and laboratory conditions

    NASA Astrophysics Data System (ADS)

    Sarah, Pariente; Sachs, Eyal

    2013-04-01

    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.

  4. Inferencing Bayesian Networks from Time Series Data Using Natural Selection

    Microsoft Academic Search

    Andrew J. Novobilski; Farhad Kamangar

    2000-01-01

    This paper describes a new framework for using natural selection to evolve Bayesian Networks for use in forecasting time series data. It extends current research by introducing a tree based representation of a candidate Bayesian Network that addresses the problem of model identification and training through the use of natural selection. The framework constructs a modified Naïve Bayesian classifier by

  5. Natural Selection in the Field and the Classroom

    ERIC Educational Resources Information Center

    Andrews, Tessa Marie

    2012-01-01

    This dissertation examined natural selection in westslope cutthroat trout ("Oncorhynchus clarkii lewisi") and undergraduate learning in the subject area natural selection. Translocation--moving individuals to a new habitat to establish, re-establish or supplement a population--is a crucial management strategy for cutthroat trout. One of…

  6. Development and Evaluation of the Conceptual Inventory of Natural Selection.

    ERIC Educational Resources Information Center

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

    2002-01-01

    Presents a diagnostic test to assess students' understanding of natural selection. Field-tests the Conceptual Inventory of Natural Selection (CINS) with nonmajors and biology majors at community colleges. Compares test scores of nonmajors with performances in interviews and discusses the correlation between the test scores and the interview…

  7. Are Humans Still Evolving? A Natural Selection Discussion Lesson

    ERIC Educational Resources Information Center

    Shields, Martin

    2004-01-01

    A study is conducted to develop sound comprehension of natural selection theory by prompting students to use its concept to explain the evolutionary status of humans. In relation to the current existence of human it is stated that human populations currently undergo microevolutionary changes in allele frequencies due to natural selection and other…

  8. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    ERIC Educational Resources Information Center

    Thagard, Paul; Findlay, Scott

    2010-01-01

    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…

  9. ENHANCEMENTS TO NATURAL ATTENUATION: SELECTED CASE STUDIES

    SciTech Connect

    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

    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).

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

    PubMed Central

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

    2011-01-01

    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

  11. Pollinator-mediated natural selection in Penstemon digitalis

    PubMed Central

    Kessler, André

    2010-01-01

    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

  12. Natural Resource Management Plan for Brookhaven National Laboratory

    SciTech Connect

    green, T.

    2011-08-15

    This comprehensive Natural Resource Management Plan (NRMP) for Brookhaven National Laboratory (BNL) was built on the successful foundation of the Wildlife Management Plan for BNL, which it replaces. This update to the 2003 plan continues to build on successes and efforts to better understand the ecosystems and natural resources found on the BNL site. The plan establishes the basis for managing the varied natural resources located on the 5,265 acre BNL site, setting goals and actions to achieve those goals. The planning of this document is based on the knowledge and expertise gained over the past 10 years by the Natural Resources management staff at BNL in concert with local natural resource agencies including the New York State Department of Environmental Conservation, Long Island Pine Barrens Joint Planning and Policy Commission, The Nature Conservancy, and others. The development of this plan is an attempt at sound ecological management that not only benefits BNL's ecosystems but also benefits the greater Pine Barrens habitats in which BNL is situated. This plan applies equally to the Upton Ecological and Research Reserve (Upton Reserve). Any difference in management between the larger BNL area and the Upton Reserve are noted in the text. The purpose of the Natural Resource Management Plan (NRMP) is to provide management guidance, promote stewardship of the natural resources found at BNL, and to sustainably integrate their protection with pursuit of the Laboratory's mission. The philosophy or guiding principles of the NRMP are stewardship, sustainability, adaptive ecosystem management, compliance, integration with other plans and requirements, and the incorporation of community involvement, where applicable. The NRMP is periodically reviewed and updated, typically every five years. This review and update was delayed to develop documents associated with a new third party facility, the Long Island Solar Farm. This two hundred acre facility will result in significant changes to this plan warranting the delay. The body of this plan establishes the management goals and actions necessary for managing the natural resources at BNL in a sustainable manner. The appendices provide specific management requirements for threatened and endangered amphibians and fish (Appendices A and B, respectively), and lists of actions in tabular format - including completed items as well as ongoing and new action items (Appendices C and D, respectively).

  13. Bayesian natural selection and the evolution of perceptual systems.

    PubMed Central

    Geisler, Wilson S; Diehl, Randy L

    2002-01-01

    In recent years, there has been much interest in characterizing statistical properties of natural stimuli in order to better understand the design of perceptual systems. A fruitful approach has been to compare the processing of natural stimuli in real perceptual systems with that of ideal observers derived within the framework of Bayesian statistical decision theory. While this form of optimization theory has provided a deeper understanding of the information contained in natural stimuli as well as of the computational principles employed in perceptual systems, it does not directly consider the process of natural selection, which is ultimately responsible for design. Here we propose a formal framework for analysing how the statistics of natural stimuli and the process of natural selection interact to determine the design of perceptual systems. The framework consists of two complementary components. The first is a maximum fitness ideal observer, a standard Bayesian ideal observer with a utility function appropriate for natural selection. The second component is a formal version of natural selection based upon Bayesian statistical decision theory. Maximum fitness ideal observers and Bayesian natural selection are demonstrated in several examples. We suggest that the Bayesian approach is appropriate not only for the study of perceptual systems but also for the study of many other systems in biology. PMID:12028784

  14. The Role of Metaphor in the Darwin Debates: Natural Theology, Natural Selection, and Christian Production of Counter-Metaphor

    E-print Network

    Neumann, Juliet

    2012-07-16

    "nature," "evolution," "natural theology," and "natural selection" is examined?within Christianity prior to Darwin, in Darwin's writing of the Origin, and in the responses of three Victorian Christian critics of science. "Natural selection...

  15. The Nature of Laboratory Learning Experiences in Secondary Science Online

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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 are teaching science online. The type and frequency of reported laboratory activities are consistent with the tradition of face-to-face instruction, using hands-on and simulated experiments. While provided examples were student-centered and required the collection of data, they failed to illustrate key components of the nature of science. The features of student-teacher interactions, student engagement, and nonverbal communications were found to be lacking and likely constitute barriers to the enactment of inquiry. These results serve as a call for research and development focused on using existing communication tools to better align with the activity of science such that the nature of science is more clearly addressed, the work of students becomes more collaborative and authentic, and the formative elements of a scientific inquiry are more accessible to all participants.

  16. Snapping shrimp prefer natural as opposed to artificial materials as their habitat in laboratory conditions

    NASA Astrophysics Data System (ADS)

    Sim, Lai Kean; Ghazali, Shahriman M.

    2014-09-01

    This study analyzed the habitat selection behavior of the snapping shrimp, Alpheus spp., comparing natural shelters (Rocks with oysters attached on the surface Sh; rocks with smooth surface, Ro and coral rubble, Co with plastic bottle. Controlled laboratory experiments were conducted to assess the habitat preference, effect of photoperiod and shrimp orientation at shelter. The current study indicated that snapping shrimp preferred natural materials but rejected plastic bottle as their shelter. Among the natural shelters, coral rubble was the most preferred habitat followed by shell and rock. Photoperiod showed minimum effect on the shrimp where they spend most of the time inside and underneath the shelters. In conclusion the current study showed that snapping shrimp preferred coral rubble as opposed to other natural material and plastic bottle. The result also suggested that plastic debris in the marine environment is not an alternative habitat for snapping shrimp.

  17. Canine Evolution in Sabretoothed Carnivores: Natural Selection or Sexual Selection?

    PubMed Central

    Randau, Marcela; Carbone, Chris; Turvey, Samuel T.

    2013-01-01

    The remarkable elongated upper canines of extinct sabretoothed carnivorous mammals have been the subject of considerable speculation on their adaptive function, but the absence of living analogues prevents any direct inference about their evolution. We analysed scaling relationships of the upper canines of 20 sabretoothed feliform carnivores (Nimravidae, Barbourofelidae, Machairodontinae), representing both dirk-toothed and scimitar-toothed sabretooth ecomorphs, and 33 non-sabretoothed felids in relation to body size in order to characterize and identify the evolutionary processes driving their development, using the scaling relationships of carnassial teeth in both groups as a control. Carnassials display isometric allometry in both sabretooths and non-sabretooths, supporting their close relationship with meat-slicing, whereas the upper canines of both groups display positive allometry with body size. Whereas there is no statistical difference in allometry of upper canine height between dirk-toothed and scimitar-toothed sabretooth ecomorphs, the significantly stronger positive allometry of upper canine height shown by sabretooths as a whole compared to non-sabretooths reveals that different processes drove canine evolution in these groups. Although sabretoothed canines must still have been effective for prey capture and processing by hypercarnivorous predators, canine morphology in these extinct carnivores was likely to have been driven to a greater extent by sexual selection than in non-sabretooths. Scaling relationships therefore indicate the probable importance of sexual selection in the evolution of the hypertrophied sabretooth anterior dentition. PMID:23951334

  18. Natural Selection: Introduction to the Nature of Explanatory Models

    NSDL National Science Digital Library

    This information is designed to connect what students have learned about scientific arguments to the role and nature of explanatory models in science. They will be asked to read and discuss a brief handout about scientific models and their function in science. They will discover that models are ideas that scientists use to explain patterns they see in the natural world, a model is an idea that has predictive and explanatory power and is consistent with other ideas about how the world works, and that models can be compared based on data, the inferences made in the model, and the prior knowledge and beliefs upon which they are based. This site includes instructional notes for the teacher and student handouts.

  19. Hamilton's forces of natural selection after forty years.

    PubMed

    Rose, Michael R; Rauser, Casandra L; Benford, Gregory; Matos, Margarida; Mueller, Laurence D

    2007-06-01

    In 1966, William D. Hamilton published a landmark paper in evolutionary biology: "The Moulding of Senescence by Natural Selection." It is now apparent that this article is as important as his better-known 1964 articles on kin selection. Not only did the 1966 article explain aging, it also supplied the basic scaling forces for natural selection over the entire life history. Like the Lorentz transformations of relativistic physics, Hamilton's Forces of Natural Selection provide an overarching framework for understanding the power of natural selection at early ages, the existence of aging, the timing of aging, the cessation of aging, and the timing of the cessation of aging. His twin Forces show that natural selection shapes survival and fecundity in different ways, so their evolution can be somewhat distinct. Hamilton's Forces also define the context in which genetic variation is shaped. The Forces of Natural Selection are readily manipulable using experimental evolution, allowing the deceleration or acceleration of aging, and the shifting of the transition ages between development, aging, and late life. For these reasons, evolutionary research on the demographic features of life history should be referred to as "Hamiltonian." PMID:17542838

  20. Natural Selection in Protected and Unprotected Populations

    NSDL National Science Digital Library

    Crissy Huffard

    2011-01-01

    In this simulation, learners model two elephant seal populations and how they change over time. Learners start with cards representing a variety of seals. Each generation, some seals survive to reproduce, passing on their traits to new seals. The amount of variation in the protected seal population stays high, while the unprotected population becomes more limited by selective pressure. In the related activity, learners can graph their data about the seal populations to show how they change over time.

  1. Genetic Programming Computers using "Natural Selection" to generate programs

    E-print Network

    Fernandez, Thomas

    themselves"; science fact or fiction? Genetic Programming uses novel optimisation techniques to "evolveGenetic Programming ­ Computers using "Natural Selection" to generate programs William B. Langdon, Adil Qureshi Dept of Computer Science, University College London. ABSTRACT Computers that "program

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

    ERIC Educational Resources Information Center

    Price, Rebecca M.

    2013-01-01

    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.

  3. The Unit of Natural Selection: Groups, Families, Individuals, or Genes?

    ERIC Educational Resources Information Center

    Reiss, Michael J.

    1985-01-01

    Offers perspectives on natural selection and the phenomenon of altruism. Presents evidence for and against the theories that evolution acts essentially on genes, on individuals, on kin, or on larger groups. (ML)

  4. The Invisible Hand of Natural Selection, and Vice Versa

    Microsoft Academic Search

    Toni Vogel Carey

    1998-01-01

    Building on work by Popper, Schweber, Nozick, Sober, and others in a still-growing literature, I explore here the conceptual kinship (not the hackneyed ideological association) between Adam Smith's 'invisible hand' and Darwinian natural selection. I review the historical ties, and examine Ullman-Margalit's 'constraints' on invisible-hand accounts, which I later re-apply to natural selection, bringing home the close relationship. These theories

  5. Natural selection in brain evolution of early hominids

    Microsoft Academic Search

    S. V. Saveliev

    2010-01-01

    Directional effect of natural selection on the arrangement of brain of anthropoids and man is reviewed. It is demonstrated\\u000a that the evolution of the human nervous system is an integrated result of several multidirectional processes. At the early\\u000a stages of the evolution of primates, the general biological principles of survival of the fittest, i.e., natural selection\\u000a of the most adapted

  6. Selective feeding of four zooplankton species on natural lake phytoplankton

    Microsoft Academic Search

    Karin Knisely; Walter Geller

    1986-01-01

    Grazing experiments evaluated by microscopical counting were conducted with different size classes of Daphnia hyalina, D. galeata, Eudiaptomus gracilis, and Cyclops sp., all from Lake Constance, using natural lake phytoplankton as food. Species-specific grazing selectivity coefficients were calculated for the dominant phytoplankton species from weekly experiments. Specific selectivities were found to be largely invariant through the growing season. All zooplankters

  7. Annotated selected references on natural resources investigations, Collier County, Florida

    USGS Publications Warehouse

    Swayze, L.J.

    1981-01-01

    A data base for future natural resources investigations in Collier County, Fla., was initiated by compiling a selected annotated bibliography. This report provides references and annotations for selected reports released between 1950 and 1978. The references are presented by subject material as follows: biologic, ecologic, geologic, geochemical, and hydrologic. (USGS)

  8. Natural selection of the critical period for language acquisition

    E-print Network

    Nowak, Martin A.

    Natural selection of the critical period for language acquisition Natalia L. Komarova1,2 and Martin of Mathematics, University of Leeds, Leeds LS2 9JT, UK The language acquisition period in humans lasts about 13 acquisition devices, which di¡er in the length of the learning period. There are two selective forces

  9. Effective Assessment: Probing Students' Understanding of Natural Selection

    ERIC Educational Resources Information Center

    Stern, Luli

    2004-01-01

    Evolution by natural selection provides the conceptual framework upon which much of modern biology is based: therefore understanding core ideas about biological evolution is an essential part of scientific literacy. Nonetheless, research repeatedly shows that high school and college students have difficulties understanding the notion of natural

  10. Variability and Selection in Natural Populations of Wood Lice

    NSDL National Science Digital Library

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

    1998-01-01

    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.

  11. Estimates of natural selection in a salmon population in captive and natural environments.

    PubMed

    Ford, Michael J; Hard, Jeffrey J; Boelts, Brant; LaHood, Eric; Miller, Jason

    2008-06-01

    Captive breeding is a commonly used strategy for species conservation. One risk of captive breeding is domestication selection--selection for traits that are advantageous in captivity but deleterious in the wild. Domestication selection is of particular concern for species that are bred in captivity for many generations and that have a high potential to interbreed with wild populations. Domestication is understood conceptually at a broad level, but relatively little is known about how natural selection differs empirically between wild and captive environments. We used genetic parentage analysis to measure natural selection on time of migration, weight, and morphology for a coho salmon (Oncorhynchus kisutch) population that was subdivided into captive and natural components. Our goal was to determine whether natural selection acting on the traits we measured differed significantly between the captive and natural environments. For males, larger individuals were favored in both the captive and natural environments in all years of the study, indicating that selection on these traits in captivity was similar to that in the wild. For females, selection on weight was significantly stronger in the natural environment than in the captive environment in 1 year and similar in the 2 environments in 2 other years. In both environments, there was evidence of selection for later time of return for both males and females. Selection on measured traits other than weight and run timing was relatively weak. Our results are a concrete example of how estimates of natural selection during captivity can be used to evaluate this common risk of captive breeding programs. PMID:18577092

  12. Natural selection and the genetics of adaptation in threespine stickleback

    PubMed Central

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

    2010-01-01

    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

  13. A network of schools for a natural hazard laboratory

    NASA Astrophysics Data System (ADS)

    Occhipinti, S.

    2012-04-01

    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.

  14. Laboratory Evidence for Microbially Mediated Silicate Mineral Dissolution in Nature

    SciTech Connect

    Ullman, W. J.; Kirchman, D. L.; Welch, S. A.; Vandevivere, P.

    1996-01-01

    Bacteria may potentially enhance or inhibit silicate mineral dissolution in nature by a variety of mechanisms. In the laboratory, some microbial metabolites enhanced dissolution rates by a factor of ten above the expected proton-promoted rate by an additional ligand-promoted mechanism focused principally at Al sites at the mineral surface. In investigations with bacteria, it was found that organic acids are produced in organic-rich/nutrient-poor cultures, resulting in increased mineral dissolution rates compared to abiotic controls. Alginate and poly-aspartate inhibited dissolution rates either by a reduction in surface reactivity or reactive surface area (or both). Bacteria may also influence dissolution rates by creating and maintaining microenvironments where metabolite concentrations are higher than in the bulk solution.

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

    E-print Network

    Cosmides, Leda

    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

  16. Natural selection on testosterone production in a wild songbird population.

    PubMed

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

    2010-06-01

    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

  17. Natural and sexual selection in a monogamous historical human population.

    PubMed

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

    2012-05-22

    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

  18. Natural and sexual selection in a monogamous historical human population

    PubMed Central

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

    2012-01-01

    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

  19. Laboratory observation of naturally occurring dust-density waves

    NASA Astrophysics Data System (ADS)

    Flanagan, Tim; Goree, John

    2010-11-01

    Dust-density waves are electrostatic compressional waves that propagate in dusty plasma. Compared to the more familiar ion-acoustic waves, in dust-density waves, inertia is provided by dust particles (instead of ions) while pressure is provided by the ions as well as electrons (not just electrons). In a laboratory experiment, we observed dust density waves in a 3D void-free dusty plasma. The waves occur naturally due to an ion-flow instability. Dust particles (4.8 microns) are levitated within the volume of a glass box that rests atop an electrode in a radio-frequency glow discharge plasma. Horizontal confinement of dust particles is provided by the plasma's natural electric field that is enhanced by the walls of the glass box, while vertical confinement is due to the electrode's sheath. We observed dust-density waves with planar wave fronts propagating in alignment with flowing ions. By directly imaging the dust particles with a 500 frame-per-second camera, we monitor the dust density modulations in both space and time. A typical wave propagates at 40 mm/s with a frequency of 24 Hz. In this work, we characterize these waves and their growth as they propagate.

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

    Microsoft Academic Search

    Esben Moland Olsen; Even Moland

    2011-01-01

    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

  1. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    NASA Astrophysics Data System (ADS)

    Thagard, Paul; Findlay, Scott

    2010-06-01

    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 derive from the intuitiveness of alternative theories. The main emotional obstacles to accepting evolution are its apparent conflict with valued beliefs about God, souls, and morality. We draw on the philosophy of science and on a psychological theory of cognitive and emotional belief revision to make suggestions about what can be done to improve acceptance of Darwinian ideas.

  2. The Chips Are Down: A Natural Selection Simulation

    NSDL National Science Digital Library

    Nick DiGiovanni

    This lesson demonstrates how natural selection operates, using different colored paper chips to represent prey and a piece of fabric as a background (the environment). The predator (student) will hunt (select chips) to show that the best adapted, by color, are NOT chosen, and others which are poorly adapted (by standing out) ARE chosen (removed). Thus, the best adapted survive and reproduce to pass on their traits. Survivors then reproduce and subsequent generations are preyed upon.

  3. Natural selection on floral volatile production in Penstemon digitalis

    PubMed Central

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

    2013-01-01

    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

  4. Using Different Examples of Natural Selection When Teaching Biology.

    ERIC Educational Resources Information Center

    Perry, Robert T.

    1993-01-01

    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)

  5. NATURAL SELECTION AND MATING CONSTRAINTS WITH GENETIC Dana Vrajitoru

    E-print Network

    Vrajitoru, Dana

    generations under the influence of natural selection. The study of the sexual reproduction and of the mat- ing into more intelligent ones. In this context, sexual reproduction is the most important mechanism, 9], some of them in particular for the genetic algorithms [16]. Sexual reproduction with completely

  6. Signatures of selection in natural populations adapted to chronic pollution

    Microsoft Academic Search

    Larissa M Williams; Marjorie F Oleksiak

    2008-01-01

    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

  7. Natural Selection: It's Not Darwin's (Or Wallace'S) Theory

    Microsoft Academic Search

    Milton Wainwright

    2008-01-01

    For nearly 150 years, since soon after the appearance of the On the Origin of Species, we have known that neither Charles Darwin nor Alfred Russel Wallace originated the theory of natural selection. This certainty is based on the fact that both of these great naturalists admitted that they were beaten to the theory by at least two other naturalists.

  8. Darwin and Natural Selection One of the most

    E-print Network

    Kammer, Thomas

    ;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

  9. 2006 Nature Publishing Group Sexual reproduction selects for robustness and

    E-print Network

    Azevedo, Ricardo

    © 2006 Nature Publishing Group Sexual reproduction selects for robustness and negative epistasis recombination brings them together into single genomes1 . This explanation requires negative epistasis, a type to identify the mechanistic and evolutionary bases of negative epistasis. Here we show that negative epistasis

  10. Natural Selection Reduced Diversity on Human Y Chromosomes

    E-print Network

    Nielsen, Rasmus

    Natural Selection Reduced Diversity on Human Y Chromosomes Melissa A. Wilson Sayres1,2 *, Kirk E of America Abstract The human Y chromosome exhibits surprisingly low levels of genetic diversity. This could chromosome. Here, using genome-wide analyses of X, Y, autosomal and mitochondrial DNA, in combination

  11. Signatures of natural selection in the human genome

    Microsoft Academic Search

    Michael Bamshad; Stephen P. Wooding

    2003-01-01

    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

  12. NATURAL SELECTION, THE HUMAN GENOME AND THE IDEA OF RACE

    E-print Network

    Pollack, Robert

    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

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

    E-print Network

    Denny, Mark

    -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

  14. The Divergence and Natural Selection of Autocatalytic Primordial Metabolic Systems

    NASA Astrophysics Data System (ADS)

    Marakushev, Sergey A.; Belonogova, Ol'ga V.

    2013-06-01

    The diversity of the central metabolism of modern organisms is caused by the existence of a few metabolic modules, combination of which produces multiple metabolic pathways. This paper analyzes biomimetically reconstructed coupled autocatalytic cycles as the basis of ancestral metabolic systems. The mechanism for natural selection and evolution in autocatalytic chemical systems may be affected by natural homeostatic parameters such as ambient chemical potentials, temperature, and pressure. Competition between separate parts of an autocatalytic network with positive-plus-negative feedback resulted in the formation of primordial autotrophic, mixotrophic, and heterotrophic metabolic systems. This work examined the last common ancestor of a set of coupled metabolic cycles in a population of protocells. Physical-chemical properties of these cycles determined the main principles of natural selection for the ancestral Bacteria and Archaea taxa.

  15. The divergence and natural selection of autocatalytic primordial metabolic systems.

    PubMed

    Marakushev, Sergey A; Belonogova, Ol'ga V

    2013-06-01

    The diversity of the central metabolism of modern organisms is caused by the existence of a few metabolic modules, combination of which produces multiple metabolic pathways. This paper analyzes biomimetically reconstructed coupled autocatalytic cycles as the basis of ancestral metabolic systems. The mechanism for natural selection and evolution in autocatalytic chemical systems may be affected by natural homeostatic parameters such as ambient chemical potentials, temperature, and pressure. Competition between separate parts of an autocatalytic network with positive-plus-negative feedback resulted in the formation of primordial autotrophic, mixotrophic, and heterotrophic metabolic systems. This work examined the last common ancestor of a set of coupled metabolic cycles in a population of protocells. Physical-chemical properties of these cycles determined the main principles of natural selection for the ancestral Bacteria and Archaea taxa. PMID:23860777

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

    SciTech Connect

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

    1984-04-01

    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.

  17. Selecting Landing Sites for the 2009 Mars Science Laboratory

    NASA Astrophysics Data System (ADS)

    Grant, J. A.; Golombek, M. P.; Vasavada, A. R.; Watkins, M. M.; Mars Landing Site Steering Committee

    2006-12-01

    Landing site selection for the 2009 Mars Science Laboratory (MSL) is underway and includes a series of open workshops for soliciting science community input regarding the landing site. The first workshop was held in Spring 2006 and focused on prioritizing 33 proposed sites for imaging by orbital spacecraft. It should be noted that the number of potential landing sites is high because MSL entry, descent, and landing (EDL) capabilities enable a small landing error circle (20 km in diameter), high landing site altitude (below 1 km, MOLA datum), and wide latitudes (plus/minus 45 degrees). The primary scientific goal of MSL is to assess the present and past habitability of environments accessed by the mission. In particular, MSL will assess the biological potential of the landing site, characterize the geology and geochemistry at appropriate spatial scales, investigate planetary processes that influence habitability, including the role of water, and characterize the broad spectrum of surface radiation. The geological, chemical, and/or biological evidence for habitability should be expected to be preserved for, accessible to and interpretable by the MSL investigations at the landing site. Because landing safely is paramount, all engineering constraints for the mission must be adhered to for a proposed site to be viewed favorably. For example, areas with potentially high winds will need to be compared with landing system tolerance during development. Slopes across length scales of 2 to 5 km, 20 meters, and 5 meters must be less than 3 degrees, 15 degrees, and 15 degrees, respectively. Rocks at the landing site should be less than 0.6 m high and in intermediate to lower abundance terrains. The landing surface must be load-bearing, radar reflective, trafficable and not be dominated by dust. Persistent cold surface temperatures and CO2 frost will negatively impact performance and areas with very low thermal inertia and very high albedo are excluded. Finally planetary protection requirements limit the MSL landing site to areas not known to have extant water or water-ice within one meter of the surface. Many of the sites proposed at the first workshop may comply with these science and engineering constraints and ongoing imaging at a variety of spatial and spectral resolutions will enable more rigorous assessment of their relative merits. In addition, the mission engineering constraints will continue to be refined during MSL design and development of the spacecraft. A second open workshop is planned for Fall 2007 and will emphasize evaluation of acquired image data, discuss any new sites revealed by orbital assets (e.g., Mars Reconnaissance Orbiter), and pare the list under consideration to a smaller number of primary and back-up sites subject to additional evaluation. An overview of the MSL mission is available at http://mars.jpl.nasa.gov/msl/overview. More information on the MSL landing site selection activities and process and proposed landing sites can be viewed at http://marsoweb.nas.nasa.gov/landingsites/and http://webgis.wr.usgs.gov/.

  18. The role of natural selection in circadian behaviour: a molecular-genetic approach.

    PubMed

    Rosato, Ezio; Kyriacou, Charalambos P

    2011-06-30

    Circadian rhythms (~24 h) in biochemistry, physiology and behaviour are found in almost all eukaryotes and some bacteria. The elucidation of the molecular components of the 24 h circadian clock in a number of model organisms in recent years has provided an opportunity to assess the adaptive value of variation in clock genes. Laboratory experiments using artificially generated mutants reveal that the circadian period is adaptive in a 24 h world. Natural genetic variation can also be studied, and there are a number of ways in which the signature of natural selection can be detected. These include the study of geographical patterns of genetic variation, which provide a first indication that selection may be at work, and the use of sophisticated statistical neutrality tests, which examine whether the pattern of variation observed is consistent with a selective rather than a neutral (or drift) scenario. Finally, examining the probable selective agents and their differential effects on the circadian phenotype of the natural variants provides the final compelling evidence for selection. We present some examples of how these types of analyses have not only enlightened the evolutionary study of clocks, but have also contributed to a more pragmatic molecular understanding of the function of clock proteins. PMID:21819385

  19. Parasite-mediated disruptive selection in a natural Daphnia population

    PubMed Central

    2008-01-01

    Background A mismatch has emerged between models and data of host-parasite evolution. Theory readily predicts that parasites can promote host diversity through mechanisms such as disruptive selection. Yet, despite these predictions, empirical evidence for parasite-mediated increases in host diversity remains surprisingly scant. Results Here, we document parasite-mediated disruptive selection on a natural Daphnia population during a parasite epidemic. The mean susceptibility of clones collected from the population before and after the epidemic did not differ, but clonal variance and broad-sense heritability of post-epidemic clones were significantly greater, indicating disruptive selection and rapid evolution. A maximum likelihood method that we developed for detecting selection on natural populations also suggests disruptive selection during the epidemic: the distribution of susceptibilities in the population shifted from unimodal prior to the epidemic to bimodal after the epidemic. Interestingly, this same bimodal distribution was retained after a generation of sexual reproduction. Conclusion These results provide rare empirical support for parasite-driven increases in host genetic diversity, and suggest that this increase can occur rapidly. PMID:18328099

  20. Natural selection on thermal performance in a novel thermal environment.

    PubMed

    Logan, Michael L; Cox, Robert M; Calsbeek, Ryan

    2014-09-30

    Tropical ectotherms are thought to be especially vulnerable to climate change because they are adapted to relatively stable temperature regimes, such that even small increases in environmental temperature may lead to large decreases in physiological performance. One way in which tropical organisms may mitigate the detrimental effects of warming is through evolutionary change in thermal physiology. The speed and magnitude of this response depend, in part, on the strength of climate-driven selection. However, many ectotherms use behavioral adjustments to maintain preferred body temperatures in the face of environmental variation. These behaviors may shelter individuals from natural selection, preventing evolutionary adaptation to changing conditions. Here, we mimic the effects of climate change by experimentally transplanting a population of Anolis sagrei lizards to a novel thermal environment. Transplanted lizards experienced warmer and more thermally variable conditions, which resulted in strong directional selection on thermal performance traits. These same traits were not under selection in a reference population studied in a less thermally stressful environment. Our results indicate that climate change can exert strong natural selection on tropical ectotherms, despite their ability to thermoregulate behaviorally. To the extent that thermal performance traits are heritable, populations may be capable of rapid adaptation to anthropogenic warming. PMID:25225361

  1. Preventing Alzheimer's disease by means of natural selection.

    PubMed

    Demetrius, Lloyd A; Driver, Jane A

    2015-01-01

    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

  2. Natural selection on thermal performance in a novel thermal environment

    PubMed Central

    Logan, Michael L.; Cox, Robert M.; Calsbeek, Ryan

    2014-01-01

    Tropical ectotherms are thought to be especially vulnerable to climate change because they are adapted to relatively stable temperature regimes, such that even small increases in environmental temperature may lead to large decreases in physiological performance. One way in which tropical organisms may mitigate the detrimental effects of warming is through evolutionary change in thermal physiology. The speed and magnitude of this response depend, in part, on the strength of climate-driven selection. However, many ectotherms use behavioral adjustments to maintain preferred body temperatures in the face of environmental variation. These behaviors may shelter individuals from natural selection, preventing evolutionary adaptation to changing conditions. Here, we mimic the effects of climate change by experimentally transplanting a population of Anolis sagrei lizards to a novel thermal environment. Transplanted lizards experienced warmer and more thermally variable conditions, which resulted in strong directional selection on thermal performance traits. These same traits were not under selection in a reference population studied in a less thermally stressful environment. Our results indicate that climate change can exert strong natural selection on tropical ectotherms, despite their ability to thermoregulate behaviorally. To the extent that thermal performance traits are heritable, populations may be capable of rapid adaptation to anthropogenic warming. PMID:25225361

  3. Preventing Alzheimer's disease by means of natural selection

    PubMed Central

    Demetrius, Lloyd A.; Driver, Jane A.

    2015-01-01

    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

  4. Genome-wide polymorphisms show unexpected targets of natural selection

    PubMed Central

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

    2012-01-01

    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

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

    ERIC Educational Resources Information Center

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

    2014-01-01

    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…

  6. Male Mating Success: Preference or Prowess? Investigating Sexual Selection in the Laboratory Using "Drosophila melanogaster"

    ERIC Educational Resources Information Center

    Coleman, Seth; Jensen, Jeffrey

    2007-01-01

    Sexual selection is the primary force affecting the evolution of the elaborate sexual displays common in animals, yet sexual selection experiments are largely absent from introductory biology laboratories. Here we describe the rationale, methodology, and results of several experiments using "Drosophila melanogaster" to demonstrate sexual selection

  7. Stick insect genomes reveal natural selection's role in parallel speciation.

    PubMed

    Soria-Carrasco, Víctor; Gompert, Zachariah; Comeault, Aaron A; Farkas, Timothy E; Parchman, Thomas L; Johnston, J Spencer; Buerkle, C Alex; Feder, Jeffrey L; Bast, Jens; Schwander, Tanja; Egan, Scott P; Crespi, Bernard J; Nosil, Patrik

    2014-05-16

    Natural selection can drive the repeated evolution of reproductive isolation, but the genomic basis of parallel speciation remains poorly understood. We analyzed whole-genome divergence between replicate pairs of stick insect populations that are adapted to different host plants and undergoing parallel speciation. We found thousands of modest-sized genomic regions of accentuated divergence between populations, most of which are unique to individual population pairs. We also detected parallel genomic divergence across population pairs involving an excess of coding genes with specific molecular functions. Regions of parallel genomic divergence in nature exhibited exceptional allele frequency changes between hosts in a field transplant experiment. The results advance understanding of biological diversification by providing convergent observational and experimental evidence for selection's role in driving repeatable genomic divergence. PMID:24833390

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

    SciTech Connect

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

    1996-04-01

    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 of limited original equipment manufacturer (OEM) model availability. Approximately 90% of all conversions were performed on compact of full-size vans and pickups, and 90% of the conversions were to bi-fuel operation. With a positive response from the fleet managers, this program helped the Federal government meet the vehicle acquisition requirements of EPACT for fiscal years 1993 and 1994, despite limited OEM model availability. The conversions also helped to establish the infrastructure needed to support further growth in the use of alternative fuel vehicles. In conclusion, the program has been successful in helping the Federal government meet the vehicle acquisition requirements of EPACT, establishing infrastructure, increasing the displacement of imported oil, and evaluating the emissions performance of converted vehicles. With the relatively widespread availability of OEM vehicles in the 1996 model year, the program is now being phased out.

  9. The theory of natural selection of Alfred Russel Wallace FRS.

    PubMed

    Bulmer, Michael

    2005-05-22

    Wallace's 1858 paper 'On the tendency of varieties to depart indefinitely from the original type' is often thought to present a theory of natural selection identical with that of Darwin. Examination of Wallace's argument shows that it is different from Darwin's because Wallace thought that an inferior variety could coexist with a superior variety until environmental deterioration forced the extinction of the inferior one. Other interpretations of Wallace's argument are re-examined in the light of this finding. PMID:16116703

  10. Compactifying de Sitter Naturally Selects a Small Cosmological Constant

    E-print Network

    Adam R. Brown; Alex Dahlen; Ali Masoumi

    2014-11-29

    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.

  11. Natural selection shaped regional mtDNA variation in humans

    Microsoft Academic Search

    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

    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

  12. Birth-order differences can drive natural selection on aging.

    PubMed

    Gillespie, Duncan O S; Trotter, Meredith V; Krishna-Kumar, Siddharth; Tuljapurkar, Shripad D

    2014-03-01

    Senescence-the deterioration of survival and reproductive capacity with increasing age-is generally held to be an evolutionary consequence of the declining strength of natural selection with increasing age. The diversity in rates of aging observed in nature suggests that the rate at which age-specific selection weakens is determined by species-specific ecological factors. We propose that, in iteroparous species, relationships between parental age, offspring birth order, and environment may affect selection on senescence. Later-born siblings have, on average, older parents than do first borns. Offspring born to older parents may experience different environments in terms of family support or inherited resources, factors often mediated by competition from siblings. Thus, age-specific selection on parents may change if the environment produces birth-order related gradients in reproductive success. We use an age-and-stage structured population model to investigate the impact of sibling environmental inequality on the expected evolution of senescence. We show that accelerated senescence evolves when later-born siblings are likely to experience an environment detrimental to lifetime reproduction. In general, sibling inequality is likely to be of particular importance for the evolution of senescence in species such as humans, where family interactions and resource inheritance have important roles in determining lifetime reproduction. PMID:24274174

  13. Crop domestication and its impact on naturally selected trophic interactions.

    PubMed

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

    2015-01-01

    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

  14. Natural selection in the field and the classroom

    NASA Astrophysics Data System (ADS)

    Andrews, Tessa Marie

    This dissertation examined natural selection in westslope cutthroat trout (Oncorhynchus clarkii lewisi) and undergraduate learning in the subject area natural selection. Translocation---moving individuals to a new habitat to establish, re-establish or supplement a population---is a crucial management strategy for cutthroat trout. One of the major questions managers face in a translocation is which population(s) should contribute individuals? Unfortunately, we often know little about the differences among potential contributing population. The goal of the first half of this dissertation was to look for differences in performance among individuals from five populations of westslope cutthroat trout. I assessed survival, growth, and condition (Chapter 2) and dispersal (Chapter 3) following the translocation of embryos from these five populations to six introduction sites in Cherry Creek. No differences existed among these populations in relative survival, growth, or condition at age 1 or 2. In contrast, statistically significant differences existed in dispersal distance among these populations. These differences were consistent across some, but not all, introduction locations. As our knowledge of evolutionary biology has continued to grow, so too has our knowledge of how students learn evolution. Students taught using active learning strategies can learn substantially more about complex scientific concepts than students taught using primarily lectures. The goal of the second half of this dissertation was to further examine how students learn natural selection and how instructors facilitate that learning. I conducted a national survey of the relationship between an instructor's use of active learning strategies and how much students learned about natural selection (Chapter 4). I used a random sample of instructors from the largest and most prestigious universities in the country so that my results could be inferred to this large population of instructors. The degree to which instructors used active learning was NOT associated with student learning in this population of typical biology instructors. However, I found that a discussion of contemporary human evolution that used active learning strategies could effectively facilitate student learning of natural selection (Chapter 5).

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

    E-print Network

    Rose, Michael R.

    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

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

    E-print Network

    Richards, Robert J.

    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

  17. The Role of Natural Selection in the Origin of Life

    NASA Astrophysics Data System (ADS)

    Fry, Iris

    2011-02-01

    It is commonly accepted among origin-of-life scientists that the emergence of life was an evolutionary process involving at one stage or other the working of natural selection. Researchers disagree, however, on the nature of the chemical infrastructure that could have formed prebiotically, enabling the evolutionary process. The division of the origin-of-life research community into `geneticists' and `metabolists' usually revolves around the issue whether the first to arise prebiotically was a genetic polymer or a primitive metabolic system. In this paper I offer an alternative classification based on the attitude to the onset of natural selection. From this perspective I add to the conventional division between gene-first and metabolism-first groups a position I call "preparatory metabolism". By this line of thought, an RNA or an RNA-like polymer could not have emerged prebiotically. Nevertheless, the onset of natural selection had to wait until such a polymer had arised. This paper examines the RNA-first, RNA-later, metabolism-first and preparatory-metabolism scenarios, assessing the weaknesses and strengths of each. I conclude that despite the recent theoretical advances in all these lines of research, and despite experimental breakthroughs, especially in overcoming several RNA-first hurdles, none of the examined paradigms has yet attained decisive experimental support. Demonstrating the evolvability of a potentially prebiotic infrastructure, whether genetic or metabolic, is a most serious challenge. So is the experimental demonstration of the emergence of such an infrastructure under prebiotic conditions. The current agenda before origin-of-life researchers of all stripes and colors is the search for the experimental means to tackle all these difficulties.

  18. Clinical Practice as Natural Laboratory for Psychotherapy Research

    Microsoft Academic Search

    Jeffrey J. Borckardt; Michael R. Nash; Martin D. Murphy; Darlene Shaw; Patrick O'Neil

    Both researchers and practitioners need to know more about how laboratory treatment protocols translate to real- world practice settings and how clinical innovations can be systematically tested and communicated to a skeptical sci- entific community. The single-case time-series study is well suited to opening a productive discourse between practice and laboratory. The appeal of case-based time-series stud- ies, with multiple

  19. Signatures of selection in natural populations adapted to chronic pollution

    PubMed Central

    2008-01-01

    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

  20. Implications of the Reduction Principle for Cosmological Natural Selection

    E-print Network

    Lee Altenberg

    2013-02-20

    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.

  1. Density-dependent regulation of natural and laboratory rotifer populations

    Microsoft Academic Search

    Terry W. Snell; Brian J. Dingmann; Manuel Serra

    2001-01-01

    Density-dependent regulation of abundance is fundamentally important in the dynamics of most animal populations. Density effects, however, have rarely been quantified in natural populations, so population models typically have a large uncertainty in their predictions. We used models generated from time series analysis to explore the form and strength of density-dependence in several natural rotifer populations. Population growth rate (r)

  2. Laboratory treatability testing of selected oil shale process wastewaters

    SciTech Connect

    Lewis, R.C.; Rawlings, G.D.

    1982-01-01

    Gas condensate wastewaters are generated by cooling of retort offgases produced by in situ facilities. These waters are characterized by high concentrations of ammonia and alkalinity, and contain moderate concentrations of dissolved organic materials. Metallic elements are present in low concentrations. Location of retorting facilities in arid areas of the western United States is expected to increase utilization of wastewater recycle/reuse options, with treatment requirements depending upon end use quality requirements. Laboratory-scale experiments were conducted with an actual modified in-situ gas condensate to assess performance of steam stripping, the activated sludge process and activated carbon adsorption for upgrading the quality of this wastewater. Steam stripping experiments were carried out with a laboratory-scale, packed tower which contacted preheated, raw gas condensate with low pressure steam in a countercurrent manner. A bench-scale, continuous-flow activated sludge system was operated to evaluate the capability of this treatment technology for removal of dissolved organics. Continuous-flow tests were conducted with steam-stripped gas condensate and effluent from the activated sludge system to assess the ability of carbon adsorption for removal of dissolved organics. A field test configuration for treatment of gas condensate wastewaters has been developed, and pilot-scale units of each treatment technology will be procured during 1981. This mobile pilot equipment will be tested at retorting facilities to demonstrate control technology performance under actual retort operating conditions.

  3. Kaon condensation, black holes, and cosmological natural selection.

    PubMed

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

    2008-08-29

    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

  4. Kaon Condensation, Black Holes and Cosmological Natural Selection

    E-print Network

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

    2008-09-04

    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.

  5. Selection and implementation of a laboratory computer system.

    PubMed

    Moritz, V A; McMaster, R; Dillon, T; Mayall, B

    1995-07-01

    The process of selection of a pathology computer system has become increasingly complex as there are an increasing number of facilities that must be provided and stringent performance requirements under heavy computing loads from both human users and machine inputs. Furthermore, the continuing advances in software and hardware technology provide more options and innovative new ways of tackling problems. These factors taken together pose a difficult and complex set of decisions and choices for the system analyst and designer. The selection process followed by the Microbiology Department at Heidelberg Repatriation Hospital included examination of existing systems, development of a functional specification followed by a formal tender process. The successful tenderer was then selected using predefined evaluation criteria. The successful tenderer was a software development company that developed and supplied a system based on a distributed network using a SUN computer as the main processor. The software was written using Informix running on the UNIX operating system. This represents one of the first microbiology systems developed using a commercial relational database and fourth generation language. The advantages of this approach are discussed. PMID:8532393

  6. Laboratory Experiences in an Introduction to Natural Science Course.

    ERIC Educational Resources Information Center

    Barnard, Sister Marquita

    1984-01-01

    Describes a two-semester course designed to meet the needs of future elementary teachers, home economists, and occupational therapists. Laboratory work includes homemade calorimeters, inclined planes, and computing. Content areas of the course include measurement, physics, chemistry, astronomy, biology, geology, and meteorology. (JN)

  7. Partial Support for Winter Wheat Laboratory Marker-Assisted-Selection Program Phil Bruckner, Winter Wheat Breeder

    E-print Network

    Maxwell, Bruce D.

    Partial Support for Winter Wheat Laboratory Marker-Assisted-Selection Program Phil Bruckner, Winter Wheat Breeder Project Description Marker-assisted selection (MAS) is an established plant breeding technology widely used by plant breeding programs around the world to supplement and enhance field

  8. 2006 Minigrant Program for UF's Natural Area Teaching Laboratory

    E-print Network

    Slatton, Clint

    of the next two minigrants. · Make detailed soil maps of NATL's successional plots. [What areas of the successional plots have natural soils and which have clays from building sites and to what depth?] · Design

  9. Exploring the nature of collisionless shocks under laboratory conditions

    PubMed Central

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

    2014-01-01

    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

  10. Exploring the nature of collisionless shocks under laboratory conditions.

    PubMed

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

    2014-01-01

    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

  11. Welcome to the University of FloridaWelcome to the University of Florida''s Living Laboratorys Living Laboratory and Its Nature Trailsand Its Nature Trails

    E-print Network

    Jawitz, James W.

    peninsular Florida: hammock, upland pine, and old-field succession. It also has a large retention basin (SEEPWelcome to the University of FloridaWelcome to the University of Florida''s Living Laboratorys formal courses and for student projects. The Florida Museum of Natural History helps manage the 27-acre

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

    ERIC Educational Resources Information Center

    Jagodzinski, Piotr; Wolski, Robert

    2015-01-01

    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…

  13. Testing sediment biological effects with the freshwater amphipod Hyalella azteca: the gap between laboratory and nature

    Microsoft Academic Search

    Feiyue Wang; Richard R. Goulet; Peter M. Chapman

    2004-01-01

    The freshwater amphipod, Hyalella azteca, is widely used in laboratory sediment toxicity and bioaccumulation tests. However, its responses in the laboratory are probably very different from those in the field. A review of the literature indicates that in its natural habitat this species complex is primarily epibenthic, derives little nutrition from the sediments, and responds primarily to contaminants in the

  14. The use of bioluminescent biotests for study of natural and laboratory aquatic ecosystems

    Microsoft Academic Search

    V. A. Kratasyuk; E. N. Esimbekova; M. I. Gladyshev; E. B. Khromichek; A. M. Kuznetsov; E. A. Ivanova

    2001-01-01

    A set of bioluminescent tests was developed to monitor water quality in natural and laboratory ecosystems. It consisted of four bioluminescent systems: luminous bacteria, coupled enzyme system NADH:FMN-oxidoreductase-luciferase and triplet enzyme systems with alcohol dehydrogenase and trypsin. The set of biotests was applied for a small forest pond (Siberia, Russia), laboratory microecosystems polluted with benzoquinone and a batch culture of

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

    E-print Network

    Ahmad, Sajjad

    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

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

    E-print Network

    Irschick, Duncan J.

    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

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

    E-print Network

    Machery, Edouard

    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

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

    E-print Network

    Fernandez, Thomas

    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

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

    E-print Network

    Evans, Steven N.

    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

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

    E-print Network

    Paris-Sud XI, Université de

    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

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

    E-print Network

    Boschetti, Fabio

    1 Visions of Evolution: Self-organization proposes what natural selection disposes David Batten1 convinced that natural selection has been the most important, but not the exclusive, means of modification (1995), concluding that each possible relationship between natural selection and self-organization may

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

    E-print Network

    West, Stuart

    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

  3. INVESTMENTS IN EDUCATION DEVELOPMENT Deterministic models of natural selection and their

    E-print Network

    Pospí�il, Zdenek

    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

  4. Direct laboratory tensile testing of select yielding rock bolt systems

    SciTech Connect

    VandeKraats, J.D.; Watson, S.O.

    1996-08-01

    Yielding rock bolt support systems have been developed to accommodate ground movement in shifting ground such as in coal operations; in creeping ground such as salt, trona, and potash; and in swelling ground associated with some clays. These systems, designed to remain intact despite ground movement, should enhance mine safety and help contain costs in areas where rebolting of rigid non-yielding systems is typically required. Four such systems were tested in straight tensile pulls in the laboratory. They include the Slip Nut System from Dywidag Systems International USA, Inc., Ischebeck`s bolt mounted Titan Load Indicator, Rocky Mountain Bolt Company`s Yielding Cable Bolt, and a rock bolt installed variation of the yielding steel post developed by RE/SPEC Inc. The first two systems are currently marketed products and the latter two are prototype systems. Each system responds to load and displacement by yielding in an unique manner. All are designed to yield at predetermined loads. A description of each system and its yield function is provided. Each system was tested over its prescribed yield range in a test machine. At least five tests were performed on each system. Each system yielded and continued to provide support according to its design. Each shows promise for ground control use in shifting or creeping rock. This work helps to illustrate the comparative differences in performance between these specialized systems and the applications where they may be most useful.

  5. Proposal for Campus Natural Area and Outdoor Teaching Laboratory

    E-print Network

    Slatton, Clint

    -drained sites in north peninsular Florida--viz., hammock, high pine, and stages of old-field succession community of north peninsular Florida. A peninsula of hammock, including a small pond and the sink), and Florida Museum of Natural History (Interpretation Department). A committee representing the major user

  6. Natural selection for costly nutrient recycling in simulated microbial metacommunities.

    PubMed

    Boyle, Richard A; Williams, Hywel T P; Lenton, Timothy M

    2012-11-01

    Recycling of essential nutrients occurs at scales from microbial communities to global biogeochemical cycles, often in association with ecological interactions in which two or more species utilise each others' metabolic by-products. However, recycling loops may be unstable; sequences of reactions leading to net recycling may be parasitised by side-reactions causing nutrient loss, while some reactions in any closed recycling loop are likely to be costly to participants. Here we examine the stability of nutrient recycling loops in an individual-based ecosystem model based on microbial functional types that differ in their metabolism. A supplied nutrient is utilised by a "source" functional type, generating a secondary nutrient that is subsequently used by two other types-a "mutualist" that regenerates the initial nutrient at a growth rate cost, and a "parasite" that produces a refractory waste product but does not incur any additional cost. The three functional types are distributed across a metacommunity in which separate patches are linked by a stochastic diffusive migration process. Regions of high mutualist abundance feature high levels of nutrient recycling and increased local population density leading to greater export of individuals, allowing the source-mutualist recycling loop to spread across the system. Individual-level selection favouring parasites is balanced by patch-level selection for high productivity, indirectly favouring mutualists due to the synergistic productivity benefits of the recycling loop they support. This suggests that multi-level selection may promote nutrient cycling and thereby help to explain the apparent ubiquity and stability of nutrient recycling in nature. PMID:22842011

  7. Definition of experiments and instruments for a communication/navigation research laboratory. Volume 2: Experiment selection

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The selection and definition of candidate experiments and the associated experiment instrumentation requirements are described. Information is presented that addresses the following study objectives: (1) determine specific research and technology needs in the comm/nav field through a survey of the scientific/technical community; (2) develop manned low earth orbit space screening criteria and compile lists of potential candidate experiments; (3) in Blue Book format, define and describe selected candidate experiments in sufficient detail to develop laboratory configuration designs and layouts; and (4) develop experiment time phasing criteria and recommend a payload for sortie can/early laboratory missions.

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

    E-print Network

    Plotkin, Joshua B.

    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

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

    E-print Network

    McCoy, Kathleen F.

    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

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

    E-print Network

    McCoy, Kathleen F.

    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

  11. Materials research at selected Japanese laboratories. Based on a 1992 visit: Overview, summary of highlights, notes on laboratories and topics

    SciTech Connect

    Not Available

    1994-02-01

    I visited Japan from June 29 to August 1, 1992. The purpose of this visit was to assess the status of materials science research at selected governmental, university and industrial laboratories and to established acquaintances with Japanese researchers. The areas of research covered by these visits included ceramics, oxide superconductors, intermetallics alloys, superhard materials and diamond films, high-temperature materials and properties, mechanical properties, fracture, creep, fatigue, defects, materials for nuclear reactor applications and irradiation effects, high pressure synthesis, self-propagating high temperature synthesis, microanalysis, magnetic properties and magnetic facilities, and surface science.

  12. Exploring Variation and Natural Selection with Fast Plants

    NSDL National Science Digital Library

    The Wisconsin Fast Plants Program

    This Immersion Unit provides a coherent series of lessons designed to guide students in developing deep conceptual understanding that is aligned with the standards, key science concepts, and essential features of classroom inquiry (as defined by the National Science Education Standards). The Unit's overarching concepts are:- Naturally occurring variations of traits in a population are influenced by genetic and environmental factors and evolve over generations by selective processes.- Science knowledge advances through inquiry.Unit Supporting Concepts:- The variation of organisms within a species increases the likelihood that at least some members of the species will survive under changed environmental conditions.- Individual organisms with certain traits are more likely than others to survive and have offspring. Changes in environmental conditions can affect the survival of individual organisms and entire species.- Some variation in heritable characteristics exists within every species. One of these characteristics gives individuals an advantage over others in surviving and reproducing, and the advantaged offspring, in turn,are more likely than others to survive and reproduce.- New varieties of cultivated plants and domestic animals have resulted from selective breeding for particular traits.- Scientists differ greatly in whatphenomena they study and how they go about their work. Although there is nofixed set of steps that all scientists follow, scientific investigations usually involve the collection of relevant evidence, the use of logical reasoning, and the application of imagination in devising hypotheses and explanations to make sense of the collected evidence.- Important contributions to the advancement of science, mathematics, and technology have been made by different kinds of people, in different cultures, at different times.In Immersion Units, students learn academic content by working like scientists: making observations, asking questions, doing further investigations to explore and explain natural phenomena, and communicating results based on evidence. Immersion Units are intended to support teachers in building a learning culture in their classrooms to sustain students? enthusiasm for engaging in scientific habits of thinking while learning rigorous science content.The first step of this unit engages students in developing a class criteria for effective record-keeping in science by guiding an inquiry into scientists' notebooks.The unit includes very complete implementation instructions (Teacher's Guide pages), student pages, and formative and summative assessments.Students investigate:- how variation within a population is influenced by environmental factors- how environmental factors influence reproductive success in a populationThis unit was developed through the large Math and Science Partnership project called System-wide Change for All Learners and Educators (SCALE), involving a collaboration among Los Angeles School District educators, California State University science and education faculty, and UW-Madison SCALE staff.

  13. Modifying effects of phenotypic plasticity on interactions among natural selection, adaptation and gene flow

    Microsoft Academic Search

    E. CRISPO

    2008-01-01

    Divergent natural selection, adaptive divergence and gene flow may interact in a number of ways. Recent studies have focused on the balance between selection and gene flow in natural populations, and empirical work has shown that gene flow can constrain adaptive divergence, and that divergent selection can constrain gene flow. A caveat is that phenotypic diversification may be under the

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

    E-print Network

    Stanford, Kyle

    The Interface Theory of Perception: Natural Selection Drives True Perception To Swift Extinction- ganism, to the extent that the category is shaped by natural selection, is a satisficing solution mate is more liberal than that of females (as predicted by the the- ory of sexual selection, e.g., [7

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

    E-print Network

    Wang, Xiao-Jing

    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

  16. Learning distinct and complementary feature-selectivities from Natural Colour Videos

    E-print Network

    Körding, Konrad Paul

    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

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

    Microsoft Academic Search

    Joshua M. Akey; Michael A. Eberle; Mark J. Rieder; Christopher S. Carlson; Mark D. Shriver; Deborah A. Nickerson; Leonid Kruglyak

    2004-01-01

    Identifying regions of the human genome that have been targets 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 variation is difficult to disentangle from the effects of neutral processes such as population demographic history, selective and demographic forces

  18. Quantifying the strength of natural selection of a motif Chen-Hsiang Yeang1

    E-print Network

    Yeang, Chen-Hsiang

    Quantifying the strength of natural selection of a motif sequence Chen-Hsiang Yeang1 Institute a method of evaluating the strength of natural selection of a motif from a family of aligned sequences of selective pressures on regulatory sequences is a central question in studying the evolution of gene

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

    ERIC Educational Resources Information Center

    Hart, Charles

    1989-01-01

    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)

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

    E-print Network

    Hendry, Andrew

    , predation, reproductive success. INTRODUCTION Natural and sexual selection often oppose each other in natureBalancing natural and sexual selection in sockeye salmon: interactions between body size, reproductive opportunity and vulnerability to predation by bears Thomas P. Quinn,* Andrew P. Hendry

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

    E-print Network

    Smith, Ronnie W.

    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

  2. Six Classroom Exercises to Teach Natural Selection to Undergraduate Biology Students

    ERIC Educational Resources Information Center

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

    2013-01-01

    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

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

    PubMed

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

    2003-09-01

    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

  4. Using natural selection to explore the adaptive potential of Chlamydomonas reinhardtii.

    PubMed

    Perrineau, Marie-Mathilde; Gross, Jeferson; Zelzion, Ehud; Price, Dana C; Levitan, Orly; Boyd, Jeffrey; Bhattacharya, Debashish

    2014-01-01

    Improving feedstock is critical to facilitate the commercial utilization of algae, in particular in open pond systems where, due to the presence of competitors and pests, high algal growth rates and stress tolerance are beneficial. Here we raised laboratory cultures of the model alga Chlamydomonas reinhardtii under serial dilution to explore the potential of crop improvement using natural selection. The alga was evolved for 1,880 generations in liquid medium under continuous light (EL population). At the end of the experiment, EL cells had a growth rate that was 35% greater than the progenitor population (PL). The removal of acetate from the medium demonstrated that EL growth enhancement largely relied on efficient usage of this organic carbon source. Genome re-sequencing uncovered 1,937 polymorphic DNA regions in the EL population with 149 single nucleotide polymorphisms resulting in amino acid substitutions. Transcriptome analysis showed, in the EL population, significant up regulation of genes involved in protein synthesis, the cell cycle and cellular respiration, whereas the DNA repair pathway and photosynthesis were down regulated. Like other algae, EL cells accumulated neutral lipids under nitrogen depletion. Our work demonstrates transcriptome and genome-wide impacts of natural selection on algal cells and points to a useful strategy for strain improvement. PMID:24658261

  5. Natural Pathogens of Laboratory Mice, Rats, and Rabbits and Their Effects on Research

    PubMed Central

    Baker, David G.

    1998-01-01

    Laboratory mice, rats, and rabbits may harbor a variety of viral, bacterial, parasitic, and fungal agents. Frequently, these organisms cause no overt signs of disease. However, many of the natural pathogens of these laboratory animals may alter host physiology, rendering the host unsuitable for many experimental uses. While the number and prevalence of these pathogens have declined considerably, many still turn up in laboratory animals and represent unwanted variables in research. Investigators using mice, rats, and rabbits in biomedical experimentation should be aware of the profound effects that many of these agents can have on research. PMID:9564563

  6. Nature Laboratory Permission Form Users: Any LDSA Faculty or Graduate Student may use this form to gain permission to

    E-print Network

    Arnold, Jonathan

    Nature Laboratory Permission Form Users: Any LDSA Faculty or Graduate Student may use this form a specimen, please describe the specimen? Agreement: The Nature Laboratory is a special collection of natural history specimens and models. These specimens and models are fragile and will break if handled

  7. The use of bioluminescent biotests for study of natural and laboratory aquatic ecosystems.

    PubMed

    Kratasyuk, V A; Esimbekova, E N; Gladyshev, M I; Khromichek, E B; Kuznetsov, A M; Ivanova, E A

    2001-03-01

    A set of bioluminescent tests was developed to monitor water quality in natural and laboratory ecosystems. It consisted of four bioluminescent systems: luminous bacteria, coupled enzyme system NADH:FMN-oxidoreductase-luciferase and triplet enzyme systems with alcohol dehydrogenase and trypsin. The set of biotests was applied for a small forest pond (Siberia, Russia), laboratory microecosystems polluted with benzoquinone and a batch culture of blue-green algae. Thereby effects of natural water compared to those of models of heavy pollution and "bloom" of blue-greens on the bioluminescent tests were revealed. The set of biotests was not affected by a natural seasonal variability of water quality in the unpolluted pond, but responded to the heavy pollution and the "bloom" of blue-greens. The set of biotests could be recommended as the alarm test to control the acute toxicity of natural water bodies. PMID:11272913

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

    PubMed Central

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

    2014-01-01

    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

  9. Natural selection on common milkweed (Asclepias syriaca) by a community of

    E-print Network

    Agrawal, Anurag

    selection analyses, latex, monarch butterfly, plant­insect interactions, quantitative genetic field natural insect herbivores (seed bug, leaf mining fly, monarch caterpillar and two beetles). Methods resistance were negatively genetically correlated with growth of monarchs. Conclusion: Selection for plant

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

    E-print Network

    Nachman, Michael

    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

  11. Variation in natural selection for growth and phlorotannins in the brown alga Fucus vesiculosus

    Microsoft Academic Search

    V. Jormalainen; T. Honkanen

    2004-01-01

    Directional selection for plant traits associated with resistance to herbivory tends to eliminate genetic variation in such traits. On the other hand, balancing selection arising from trade-offs between resistance and growth or spatially variable selection acts against the elimination of genetic variation. We explore both the amount of genetic variation and variability of natural selection for growth and concentration of

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

    PubMed Central

    Bell, Rayna C.; Zamudio, Kelly R.

    2012-01-01

    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

  13. California ground squirrel body temperature regulation patterns measured in the laboratory and in the natural environment.

    PubMed

    Muchlinski, A E; Baldwin, B C; Padick, D A; Lee, B Y; Salguero, H S; Gramajo, R

    1998-06-01

    Body temperature (Tb) was measured by telemetry in both laboratory maintained and natural environment California ground squirrels, Spermophilus beecheyi. Laboratory animals had a mean diurnal Tb of 37.5 degrees C under conditions of LD 14:10, 20 degrees C and 36.5 degrees C under conditions of LD 10:14, 20 degrees C (P < 0.01). Nocturnal mean Tbs were 37.1 and 35.2 degrees C, respectively (P < 0.05). Mean diurnal Tbs for each animal in the natural environment ranged from 39.3 to 40.1 degrees C (mean = 39.6 degrees C) during both study seasons which included the hot season months of March through August and the cool season months of December through February. Natural environment hot season mean Tb was not significantly different from cool season mean Tb but both mean Tbs were significantly different from the diurnal mean Tbs measured in the laboratory (P < 0.05). California ground squirrels exhibit an open-field stress induced hyperthermia in the laboratory which can be extended for periods up to 6 h. The hyperthermic response is blocked by L-propranolol at a dosage of 15 mg kg-1. Laboratory animals do not habituate to repeated open-field exposures over a five consecutive day period. It is suggested that stress hyperthermia might be a normal component of thermoregulation in some free-living ground squirrels because of the openness of the habitat in which they exist. PMID:9773514

  14. Context-dependent fright reactions in captive European minnows: the importance of naturalness in laboratory experiments

    Microsoft Academic Search

    PHILIP W IRVING; ANNE E MAGURRAN

    1997-01-01

    The responses of ostariophysan fish to alarm substance (Schreckstoff) have been investigated extensively in the laboratory but there have been few tests of its role under natural conditions. Furthermore, existing studies of the efficacy of Schreckstoff as an alarm substance in the wild have typically employed indirect approaches and have failed to document specific behaviour in a quantitative manner. European

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

    ERIC Educational Resources Information Center

    Vhurumuku, Elaosi

    2011-01-01

    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…

  16. Composition of Bacterial Communities Associated with Natural and Laboratory Populations of Asobara tabida Infected with Wolbachia

    Microsoft Academic Search

    Karima Zouache; Denis Voronin; Van Tran-Van; Patrick Mavingui

    2009-01-01

    Asobara tabida wasps are fly endoparasitoids that naturally harbor three Wolbachia strains, which induce cytoplasmic incompatibility and control oogenesis. To investigate whether other bacteria play a role in wasp biology, we surveyed the bacterial communities of wild A. tabida populations originating from different regions of France and of laboratory colonies using PCR-denaturing gradient gel electrophoresis and culture methods. Proteobacteria and

  17. Six Classroom Exercises to Teach Natural Selection to Undergraduate Biology Students

    PubMed Central

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

    2013-01-01

    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 selection and also include discussions on sexual selection, molecular evolution, evolution of complex traits, and the evolution of behavior. The set of six topics gives students the opportunity to see how natural selection operates in a variety of contexts. Pre- and postinstruction testing showed students’ understanding of natural selection increased substantially after completing this series of learning activities. Testing throughout this unit showed steadily increasing student understanding, and surveys indicated students enjoyed the activities. PMID:24006396

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

    E-print Network

    Purugganan, Michael D.

    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

  19. Copyright 0 1995by the Genetics Society of America The Fundamental Theorem of Natural Selection in Ewens' Sense

    E-print Network

    Lessard, Sabin

    Copyright 0 1995by the Genetics Society of America The Fundamental Theorem of Natural Selection of Natural Selection in Ewens' sense is valid in the case of fertility selection: the additive genetic principle to the case of fertility selection. THE FundamentalTheorem of Natural Selection (FTNS

  20. Clients and clinician satisfaction with laboratory services at selected government hospitals in eastern Ethiopia

    PubMed Central

    2013-01-01

    Background In clinical laboratory service, patients and clinical service providers are the primary focus of survey of satisfaction in many countries. The objective of the study was to assess clients’ and clinicians’ satisfaction with laboratory services at selected government hospitals in eastern Ethiopia from May to June, 2010. Findings A cross sectional study was conducted at Dil Chora, Jugal, Hiwot Fana and Bisidimo hospitals. Data were collected from 429 patients and 54 clinical service providers. A statistical analysis was conducted using Likert Scale and SPSS Version 16 software. Most of the patients (87.6%) were satisfied with the laboratory services. The lowest [2.48?±?1.39] and highest [4.27?±?0.83] rate satisfaction were on cleanness of latrine to collect specimens and availability of laboratory staff on working hours respectively. The extent of the patients’ satisfaction was different among the study hospitals (P-value?laboratory services. The lowest [3.02?±?1.36] and highest [3.78?±?1.03] rate of satisfaction were found on critical value notification and timely test results for HIV/AIDS patients care respectively. Conclusion The overall degree of customers’ satisfaction with laboratory services was high. But there were some services such as the cleanness of latrines, information given during specimen collection outside laboratory and critical value notification which need attention. Therefore, the hospital administrations and the laboratory departments should work harder and closely to solve the identified problems. Further study with a larger sample size and more factors is recommended. PMID:23324260

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

    PubMed

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

    2015-03-01

    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

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

    PubMed Central

    Thulin, Elisabeth; Sundqvist, Martin

    2015-01-01

    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

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

    SciTech Connect

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

    1998-02-01

    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.

  4. Toxicity of naturally-contaminated manganese soil to selected crops.

    PubMed

    Ková?ik, Jozef; Št?rbová, Dagmar; Babula, Petr; Švec, Pavel; Hedbavny, Josef

    2014-07-23

    The impact of manganese excess using naturally contaminated soil (Mn-soil, pseudototal Mn 6494 vs 675 ?g g(-1) DW in control soil) in the shoots of four crops was studied. Mn content decreased in the order Brassica napus > Hordeum vulgare > Zea mays > Triticum aestivum. Growth was strongly depressed just in Brassica (containing 13696 ?g Mn g(-1) DW). Some essential metals (Zn, Fe) increased in Mn-cultured Brassica and Zea, while macronutrients (K, Ca, Mg) decreased in almost all species. Toxic metals (Ni and Cd) were rather elevated in Mn-soil. Microscopy of ROS, NO, lipid peroxidation, and thiols revealed stimulation in all Mn-cultured crops, but changes were less visible in Triticum, a species with low shoot Mn (2363 ?g g(-1) DW). Antioxidative enzyme activities were typically enhanced in Mn-cultured plants. Soluble phenols increased in Brassica only while proteins rather decreased in response to Mn excess. Inorganic anions (chloride, sulfate, and phosphate) were less accumulated in almost all Mn-cultured crops, while the nitrate level rather increased. Organic anions (malate, citrate, oxalate, acetate, and formate) decreased or remained unaffected in response to Mn-soil culture in Brassica, Hordeum, and Triticum but not in Zea. However, the role of organic acids in Mn uptake in these species is not assumed. Because control and Mn-soil differed in pH (6.5 and 3.7), we further studied its impact on Mn uptake in solution culture (using Mn concentration ?5 mM deducted from water-soluble fraction of Mn-soil). Shoot Mn contents in Mn-treated plants were similar to those observed in soil culture (high in Brassica and low in Triticum) and pH had negligible impact. Fluorescence indicator of "general ROS" revealed no extensive or pH-dependent impact either in control or Mn-cultured roots. Observed toxicity of Mn excess to common crops urges for selection of cultivars with higher tolerance. PMID:24965550

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

    Microsoft Academic Search

    Marc Mangel

    1991-01-01

    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

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

    Microsoft Academic Search

    David Batten; Fabio Boschetti

    2008-01-01

    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

  7. A Hands-On Exercise to Demonstrate Evolution by Natural Selection & Genetic Drift

    ERIC Educational Resources Information Center

    Young, Helen J.; Young, Truman P.

    2003-01-01

    Although students "learn" (i.e., hear about) the components of evolution by natural selection in high school biology courses, few of them truly understand or remember them. Evolution by natural selection, although seemingly simple, requires that several conditions be met. The trait of concern must exhibit variation within the population; this…

  8. Evolution of Students' Ideas about Natural Selection through a Constructivist Framework

    ERIC Educational Resources Information Center

    Baumgartner, Erin; Duncan, Kanesa

    2009-01-01

    Educating students about the process of evolution through natural selection is vitally important because not only is it the unifying theory of biological science, it is also widely regarded as difficult for students to fully comprehend. Anderson and colleagues (2002) describe alternative ideas and misconceptions about natural selection as highly…

  9. 2006 Nature Publishing Group Intensity of sexual selection along the

    E-print Network

    Pitnick, Scott

    intraspecific experimental evolution techniques and interspecific comparative techniques. Our results confirm the foundations of sexual selection theory. Post- copulatory sexual selection on males (that is, sperm competition that by females), sperm become less abundant, ova become relatively less rare, and competition between males

  10. Predator-mediated natural selection on the wings of the damselfly Calopteryx splendens: differences in selection among trait types.

    PubMed

    Kuchta, Shawn R; Svensson, Erik I

    2014-07-01

    Traits that increase mating success in males may come at a cost, such as an increased risk of predation. However, predator-mediated selection is challenging to document in natural populations, hampering our understanding of the trade-offs between sexual selection and predation. Here we report on a study of predator-mediated natural selection on wing traits in the damselfly Calopteryx splendens, the males of which possess conspicuous wing patches. Wagtails (genus Motacilla) are important avian predators of C. splendens, capturing them in flight and removing the wings prior to consumption. Using geometric morphometric techniques, we quantified the strength and mode of selection on wing traits by comparing wings from depredated individuals with the standing variation present in the population. Our results reveal that predator-mediated selection is stronger on secondary sexual characters than on size and shape, suggesting that traits related to flight performance are closer to their adaptive peaks. This could be a consequence of the long-term evolutionary association with avian predators, whereas stronger selection on conspicuous secondary sexual traits may reflect trade-offs between sexual and natural selection. Finally, even though C. splendens possesses nearly identical fore- and hindwings, we found evidence for divergent selection between them. PMID:24921603

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

    PubMed Central

    2014-01-01

    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

  12. North American Natural Gas Markets: Selected technical studies

    SciTech Connect

    Huntington, H.G.; Schuler, G.E. (eds.)

    1989-04-01

    The Energy Modeling Forum (EMF) was established in 1976 at Stanford University to provide a structural framework within which energy experts, analysts, and policymakers could meet to improve their understanding of critical energy problems. The ninth EMF study, North American Natural Gas Markets, was conducted by a working group comprised of leading natural gas analysts and decision-makers from government, private companies, universities, and research and consulting organizations. The EMF 9 working group met five times from October 1986 through June 1988 to discuss key issues and analyze natural gas markets. This third volume includes technical papers that support many of the conclusions discussed in the EMF 9 summary report (Volume 1) and full working group report (Volume 2). These papers discuss the results from the individual models as well as some nonmodeling analysis related to US natural gas imports and industrial natural gas demand. Individual papers have been processed separately for inclusion in the Energy Science and Technology Database.

  13. North American Natural Gas Markets: Selected technical studies. Volume 3

    SciTech Connect

    Huntington, H.G.; Schuler, G.E. [eds.

    1989-04-01

    The Energy Modeling Forum (EMF) was established in 1976 at Stanford University to provide a structural framework within which energy experts, analysts, and policymakers could meet to improve their understanding of critical energy problems. The ninth EMF study, North American Natural Gas Markets, was conducted by a working group comprised of leading natural gas analysts and decision-makers from government, private companies, universities, and research and consulting organizations. The EMF 9 working group met five times from October 1986 through June 1988 to discuss key issues and analyze natural gas markets. This third volume includes technical papers that support many of the conclusions discussed in the EMF 9 summary report (Volume 1) and full working group report (Volume 2). These papers discuss the results from the individual models as well as some nonmodeling analysis related to US natural gas imports and industrial natural gas demand. Individual papers have been processed separately for inclusion in the Energy Science and Technology Database.

  14. Idaho National Laboratory Materials and Fuels Complex Natural Phenomena Hazards Flood Assessment

    SciTech Connect

    Gerald Sehlke; Paul Wichlacz

    2010-12-01

    This report presents the results of flood hazards analyses performed for the Materials and Fuels Complex (MFC) and the adjacent Transient Reactor Experiment and Test Facility (TREAT) located at Idaho National Laboratory. The requirements of these analyses are provided in the U.S. Department of Energy Order 420.1B and supporting Department of Energy (DOE) Natural Phenomenon Hazard standards. The flood hazards analyses were performed by Battelle Energy Alliance and Pacific Northwest National Laboratory. The analyses addressed the following: • Determination of the design basis flood (DBFL) • Evaluation of the DBFL versus the Critical Flood Elevations (CFEs) for critical existing structures, systems, and components (SSCs).

  15. California ground squirrel body temperature regulation patterns measured in the laboratory and in the natural environment

    Microsoft Academic Search

    Alan E Muchlinski; Bart C Baldwin; Don A Padick; Brian Y Lee; Hugo S Salguero; Ruth Gramajo

    1998-01-01

    Body temperature (Tb) was measured by telemetry in both laboratory maintained and natural environment California ground squirrels, Spermophilus beecheyi. Laboratory animals had a mean diurnal Tb of 37.5oC under conditions of LD 14:10, 20°C and 36.5oC under conditions of LD 10:14, 20oC (P<0.01). Nocturnal mean Tbs were 37.1 and 35.2oC, respectively (P<0.05). Mean diurnal Tbs for each animal in the

  16. I'm Looking Over a White-Striped Clover: A Natural Selection Case

    NSDL National Science Digital Library

    Evarts, Susan

    2006-11-28

    This case study examines the process of natural selection, using the example of white clover. Students will learn the concepts of variation, natural selection, fitness, selection pressure, evolution, and adaptation.The lesson would be useful for high school or lower level undergraduate students studying biology or botany. The case study and teaching notes may be downloaded in PDF format. The site also includes a section for instructor feedback where general comments may be read and contributed.

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

    E-print Network

    Crespi, Bernard J.

    Abstract Sexual isolation can evolve due to natural selection against hybrids (reinforcement). However, many different forms of hybrid dysfunction, and selective processes that do not involve hybrids, can contribute to the evolution of sexual isolation. Here we review how different selective processes

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

    Microsoft Academic Search

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

    2003-01-01

    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

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

    E-print Network

    van Lambalgen, Michiel

    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

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

    NASA Astrophysics Data System (ADS)

    Jagodzi?ski, Piotr; Wolski, Robert

    2015-02-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Jagodzi?ski, Piotr; Wolski, Robert

    2014-09-01

    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.

  2. Dynamics of extinction and the selection of nature reserves.

    PubMed Central

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

    2002-01-01

    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

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

    PubMed Central

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

    1976-01-01

    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

  4. Gene expression of ABC transporters in Cooperia oncophora after field and laboratory selection with macrocyclic lactones.

    PubMed

    Tydén, Eva; Skarin, Moa; Höglund, Johan

    2014-12-01

    The most widespread helminth parasites of grazing cattle in northern Europe are the gastrointestinal nematodes Ostertagia ostertagi and Cooperia oncophora. Heavy reliance on the use of macrocyclic lactone (ML) in cattle has led to world-wide emergence of resistance to this drug class in C. oncophora. There is evidence that members of the ATP-binding cassette (ABC) transporter family, such as P-glycoproteins (P-gp) and multidrug-resistant proteins (MRP), play a role in resistance to ML. In this study gene expression of Con-pgp9, Con-pgp11, Con-pgp12, Con-pgp16 and Con-mrp1 was examined in two isolates of C. oncophora sharing the same genetic background but exposed to ML differently. For isolate one (Laboratory-selected), adult worms were recovered before and after treatment with ML in vivo. For isolate two (Field-selected), adult worms were collected from tracer animals that had never received anthelmintics themselves. One group grazed together with untreated animals and one group grazed with animals that received suppressive prophylactic treatment with ML at monthly intervals for up to two consecutive grazing seasons. Real-time PCR data demonstrated differences in gene expression after ML selection, with the highest constitutive expression levels for Con-pgp16 and Con-mrp1. Remarkably, the same pattern of increasing expression levels of the ABC transport genes was observed in both Laboratory- and Field-selected isolates, despite the Field-selected isolate not being directly exposed to ML. The higher expression levels of ABC transporters observed in the Field-selected isolate was thus not a response to direct exposure to ML, but rather appeared to reflect a genetic characteristic inherited from worms in the previous generation which had survived exposure to ML in the co-grazing treated animals. PMID:25619799

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

    E-print Network

    Bowden, Richard

    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

  6. Selective whole genome amplification for resequencing target microbial species from complex natural samples.

    PubMed

    Leichty, Aaron R; Brisson, Dustin

    2014-10-01

    Population genomic analyses have demonstrated power to address major questions in evolutionary and molecular microbiology. Collecting populations of genomes is hindered in many microbial species by the absence of a cost effective and practical method to collect ample quantities of sufficiently pure genomic DNA for next-generation sequencing. Here we present a simple method to amplify genomes of a target microbial species present in a complex, natural sample. The selective whole genome amplification (SWGA) technique amplifies target genomes using nucleotide sequence motifs that are common in the target microbe genome, but rare in the background genomes, to prime the highly processive phi29 polymerase. SWGA thus selectively amplifies the target genome from samples in which it originally represented a minor fraction of the total DNA. The post-SWGA samples are enriched in target genomic DNA, which are ideal for population resequencing. We demonstrate the efficacy of SWGA using both laboratory-prepared mixtures of cultured microbes as well as a natural host-microbe association. Targeted amplification of Borrelia burgdorferi mixed with Escherichia coli at genome ratios of 1:2000 resulted in >10(5)-fold amplification of the target genomes with <6.7-fold amplification of the background. SWGA-treated genomic extracts from Wolbachia pipientis-infected Drosophila melanogaster resulted in up to 70% of high-throughput resequencing reads mapping to the W. pipientis genome. By contrast, 2-9% of sequencing reads were derived from W. pipientis without prior amplification. The SWGA technique results in high sequencing coverage at a fraction of the sequencing effort, thus allowing population genomic studies at affordable costs. PMID:25096321

  7. 1M. Panahi, S. Skogestad ' Controlled Variables Selection for a Natural Gas to Liquids (GTL) process' Controlled Variables Selection for a

    E-print Network

    Skogestad, Sigurd

    1M. Panahi, S. Skogestad ' Controlled Variables Selection for a Natural Gas to Liquids (GTL) process' Controlled Variables Selection for a Natural Gas to Liquids (GTL) process Mehdi Panahi Sigurd. Panahi, S. Skogestad ' Controlled Variables Selection for a Natural Gas to Liquids (GTL) process' Mode I

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

    Microsoft Academic Search

    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

    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

  9. Mini-conference on Angular Momentum Transport in Laboratory and Nature

    SciTech Connect

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

    2008-05-06

    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.

  10. Transgenic Insecticidal Crops and Natural Enemies: A Detailed Review of Laboratory Studies

    Microsoft Academic Search

    Gabor L. Lövei; David A. Andow; Salvatore Arpaia

    2009-01-01

    This review uses a data-driven, quantitative method to summarize the published, peer-reviewed literature about the impact of genetically modiÞed (GM) plants on arthropod natural enemies in laboratory experiments. The method is similar to meta-analysis, and, in contrast to a simple author-vote counting method used by several earlier reviews, gives an objective, data-driven summary of existing knowledge about these effects. SigniÞcantly

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

    Microsoft Academic Search

    Corinne Le Quéré; Laurent Bopp; Ina Tegen

    2002-01-01

    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

  12. Nature of the Organic Signature in Dust from the Interstellar Medium: Laboratory Analog Studies

    Microsoft Academic Search

    Minoru M. Freund; Friedemann T. Freund; Aaron Staple; John Scoville

    2002-01-01

    We measured the infrared (IR) VCH absorption bands around 3.4mum (2800 - 3000cm-1) in large laboratory- grown magnesium oxide (MgO) and natural olivine single crystals that crystallized from CO\\/C02\\/H20 saturated melts. These bands are very similar to those from many astronomical sources, such as from dust in the diffuse interstellar medium (ISM) , from the outflow of evolved stars, etc.,

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

    Microsoft Academic Search

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

    2010-01-01

    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,

  14. Design and validation of laboratory-scale simulations for selecting tribomaterials and surface treatments

    SciTech Connect

    Blau, P.J. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-05-01

    Engineering approaches to solving tribology problems commonly involve friction, lubrication, or wear testing, either in the field or in a laboratory setting. Since wear and friction are properties of the materials in the larger context of the tribosystem, the selection of appropriate laboratory tribotesting procedures becomes critically important. Laboratory simulations must exhibit certain key characteristics of the application in order for the test results to be relevant, but they may not have to mimic all operating conditions. The current paper illustrates a step-by-step method to develop laboratory-scale friction and wear simulations based on a tribosystem analysis. Quantitative or qualitative metrics are established and used to validate the effectiveness of the tribosimulation. Sometimes standardized test methods can be used, but frequently a new type of test method or procedure must be developed. There are four factors to be addressed in designing effective simulations: (1) contact macrogeometry and the characteristics of relative motion, (2) pressure--velocity relationships, (3) thermal and chemical environment (including type of lubrication), and (4) the role of third-bodies. In addition, there are two typical choices of testing philosophy: (1) the worst-case scenario and, (2) the nominal-operations scenario. Examples of the development and use of simulative friction and wear tests are used to illustrate major points.

  15. Laboratory coating evaluation and its relationship with the selection to protect pipeline against external corrosion

    SciTech Connect

    Rodriguez, V.; Perozo, E.; Castafieda, L.; Alvarez, E. [INTEVEP, S.A., Caracas (Venezuela). Material Technology Dept.

    1998-12-31

    There are several pipeline external coatings classified into different types, among them are extruded and tape polyethylene, fusion bonded epoxy (FBE), coal tar enamel, coal tar epoxy, polyurethane, wax, cementitious epoxy and multilayer systems. These coatings are assumed to protect the pipeline for a certain period of time. In order to select the most appropriate coating, several accelerated laboratory tests need to be carried out to obtain their properties and correlate them with the performance in the field. Cathodic disbonding tests at different temperatures and voltages, adhesion at different temperatures, impact resistance, loss of adhesion against time under water immersion conditions, differential scanning calorimetry analysis and water uptake are the most important tests to carry out in this study. The results indicate that coatings perform differently in each test. For this reason the selection must be done according to the soil characteristics, considering the results obtained in laboratory. This paper will provide a guideline to select a coating for a specific environment and the results that should be expected in the field. For example, the multilayer system presented the best performance like low cathodic disbonding, excellent adhesion, high impact resistance, excellent behavior under hot water immersion and high temperature resistance. This system can be used in all types of soil with high life time expectancy in protecting the pipeline. On the other hand, the polyurethane coating presented high impact resistance but very low adhesion and high cathodic disbonding that limits its use in corrosive soil.

  16. Gene flow and the limits to natural selection

    Microsoft Academic Search

    Thomas Lenormand

    2002-01-01

    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.

  17. Mortality among Plants and its Bearing on Natural Selection

    Microsoft Academic Search

    R. Weatherall

    1931-01-01

    I HAVE read with great interest the letters from Prof. Salisbury and Dr. J. Phillips which have appeared in NATURE dealing with mortality in plants at different stages of their life histories. The observations are of the greatest importance, but I doubt whether the interpretation advanced by Prof. Salisbury in his letter of May 31, 1930, is supported by the

  18. 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...

  19. Mouse Strain Type is Not Selective for a Laboratory-adapted Strain of Schistosoma mansoni

    PubMed Central

    Liu, Shi Fan; Prasad, Jayendra; Blanton, Ronald E.

    2013-01-01

    We genotyped pooled adult worms of Schistosoma mansoni from infected CF1, C57BL/6, BALB/c, and BALB/c interferon gamma knockout mice in order to investigate if mouse strain differences selected for parasite genotypes. We also compared differentiation in eggs collected from liver and intestines to determine if there was differential distribution of parasite strains in the vertebrate host that might account for any genotype selection. We found that mouse strains with differing immune responses did not differ in resistance to infection and did not select for parasite genotypes. S. mansoni genotypes were also equally distributed in tissues and there was no difference between adult and egg allele frequencies. Differing immune responses in these mouse strains does not significantly affect the degree or the nature of host resistance to schistosomes. PMID:21506771

  20. Genome Sequencing Reveals Loci under Artificial Selection that Underlie Disease Phenotypes in the Laboratory Rat

    PubMed Central

    Atanur, Santosh S.; Diaz, Ana Garcia; Maratou, Klio; Sarkis, Allison; Rotival, Maxime; Game, Laurence; Tschannen, Michael R.; Kaisaki, Pamela J.; Otto, Georg W.; Ma, Man Chun John; Keane, Thomas M.; Hummel, Oliver; Saar, Kathrin; Chen, Wei; Guryev, Victor; Gopalakrishnan, Kathirvel; Garrett, Michael R.; Joe, Bina; Citterio, Lorena; Bianchi, Giuseppe; McBride, Martin; Dominiczak, Anna; Adams, David J.; Serikawa, Tadao; Flicek, Paul; Cuppen, Edwin; Hubner, Norbert; Petretto, Enrico; Gauguier, Dominique; Kwitek, Anne; Jacob, Howard; Aitman, Timothy J.

    2013-01-01

    Summary Large numbers of inbred laboratory rat strains have been developed for a range of complex disease phenotypes. To gain insights into the evolutionary pressures underlying selection for these phenotypes, we sequenced the genomes of 27 rat strains, including 11 models of hypertension, diabetes, and insulin resistance, along with their respective control strains. Altogether, we identified more than 13 million single-nucleotide variants, indels, and structural variants across these rat strains. Analysis of strain-specific selective sweeps and gene clusters implicated genes and pathways involved in cation transport, angiotensin production, and regulators of oxidative stress in the development of cardiovascular disease phenotypes in rats. Many of the rat loci that we identified overlap with previously mapped loci for related traits in humans, indicating the presence of shared pathways underlying these phenotypes in rats and humans. These data represent a step change in resources available for evolutionary analysis of complex traits in disease models. PaperClip PMID:23890820

  1. Ecology of Neoschongastia americana (Hirst): laboratory life cycle, developmental period in the field and influence of selected external factors.

    E-print Network

    Cunningham, Jerry Real

    1974-01-01

    ECOLOGY OF NEOSCHONGASTIA AMERICANA (HIRST): LABORATORY LIFE CYCLE, DEVELOPMENTAL PERIOD IN THE FIELD AND INFLUENCE OF SELECTED EXTERNAL FACTORS A Thesis by JERRY REAL CUNNINGHAM Submitted to the Graduate College of Texas A&? University... in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 19/4 Major Subject: Entomology ECOLOGY OF NEOSCHONGASTIA AMERICANA (HIRST): LABORATORY LIFE CYCLE, DEVELOPMENTAL PERIOD IN THE FIELD AND INFLUENCE OF SELECTED EXTERNAL...

  2. The Evolution of Recombination: Removing the Limits to Natural Selection

    PubMed Central

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

    1997-01-01

    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

  3. Natural selection of mitochondria during somatic lifetime promotes healthy aging

    PubMed Central

    Rodell, Anders; Rasmussen, Lene J.; Bergersen, Linda H.; Singh, Keshav K.; Gjedde, Albert

    2013-01-01

    Stimulation of mitochondrial biogenesis during life-time challenges both eliminates disadvantageous properties and drives adaptive selection of advantageous phenotypic variations. Intermittent fission and fusion of mitochondria provide specific targets for health promotion by brief temporal stressors, interspersed with periods of recovery and biogenesis. For mitochondria, the mechanisms of selection, variability, and heritability, are complicated by interaction of two independent genomes, including the multiple copies of DNA in each mitochondrion, as well as the shared nuclear genome of each cell. The mechanisms of stress-induced fission, followed by recovery-induced fusion and biogenesis, drive the improvement of mitochondrial functions, not only as directed by genotypic variations, but also as enabled by phenotypic diversity. Selective adaptation may explain unresolved aspects of aging, including the health effects of exercise, hypoxic and poisonous preconditioning, and tissue-specific mitochondrial differences. We propose that intermittent purposeful enhancement of mitochondrial biogenesis by stressful episodes with subsequent recovery paradoxically promotes adaptive mitochondrial health and continued healthy aging. PMID:23964235

  4. The Impacts of Selected Natural Plant Chemicals on Terrestrial Invertebrates

    Microsoft Academic Search

    Neal Sorokin; Jeanette Whitaker

    Plants produce thousands of chemicals that are not necessarily involved in their primary metabolism, but are likely to be\\u000a involved in plant defence, communication and competition. These chemicals may be stored within plant tissues, e.g. to act\\u000a as a defence from herbivorous predators, or may be actively released into the surrounding environment. Natural chemicals can\\u000a enter the environment via a

  5. STATE OF CALIFORNIA THE NATURAL RESOURCES AGENCY EDMUND BROWN JR, Governor NOTICE OF SELECTION

    E-print Network

    STATE OF CALIFORNIA ­ THE NATURAL RESOURCES AGENCY EDMUND BROWN JR, Governor NOTICE OF SELECTION. 788 20 808 Digital Energy, Inc. 800 0 800 Enovity, Inc. 701 20 721 Resource Solutions Group 537 10 547

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

    Microsoft Academic Search

    W. E. Crusio

    \\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

  7. Natural Selection Constrains Neutral Diversity across A Wide Range of Species

    PubMed Central

    Corbett-Detig, Russell B.; Hartl, Daniel L.; Sackton, Timothy B.

    2015-01-01

    The neutral theory of molecular evolution predicts that the amount of neutral polymorphisms within a species will increase proportionally with the census population size (Nc). However, this prediction has not been borne out in practice: while the range of Nc spans many orders of magnitude, levels of genetic diversity within species fall in a comparatively narrow range. Although theoretical arguments have invoked the increased efficacy of natural selection in larger populations to explain this discrepancy, few direct empirical tests of this hypothesis have been conducted. In this work, we provide a direct test of this hypothesis using population genomic data from a wide range of taxonomically diverse species. To do this, we relied on the fact that the impact of natural selection on linked neutral diversity depends on the local recombinational environment. In regions of relatively low recombination, selected variants affect more neutral sites through linkage, and the resulting correlation between recombination and polymorphism allows a quantitative assessment of the magnitude of the impact of selection on linked neutral diversity. By comparing whole genome polymorphism data and genetic maps using a coalescent modeling framework, we estimate the degree to which natural selection reduces linked neutral diversity for 40 species of obligately sexual eukaryotes. We then show that the magnitude of the impact of natural selection is positively correlated with Nc, based on body size and species range as proxies for census population size. These results demonstrate that natural selection removes more variation at linked neutral sites in species with large Nc than those with small Nc and provides direct empirical evidence that natural selection constrains levels of neutral genetic diversity across many species. This implies that natural selection may provide an explanation for this longstanding paradox of population genetics. PMID:25859758

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

    PubMed Central

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

    2014-01-01

    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

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

    PubMed

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

    2015-04-01

    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

  10. New selective acetylcholinesterase inhibitors designed from natural piperidine alkaloids.

    PubMed

    Viegas, Cláudio; Bolzani, Vanderlan S; Pimentel, Luísa S B; Castro, Newton G; Cabral, Rafael F; Costa, Rodrigo S; Floyd, Corinne; Rocha, Mônica S; Young, Maria C M; Barreiro, Eliezer J; Fraga, Carlos A M

    2005-07-01

    Five new piperidine alkaloids were designed from natural (-)-3-O-acetyl-spectaline and (-)-spectaline that were obtained from the flowers of Senna spectabilis (sin. Cassia spectabilis, Leguminosae). Two semi-synthetic analogues (7 and 9) inhibited rat brain acetylcholinesterase, showing IC50 of 7.32 and 15.1 microM, and were 21 and 9.5 times less potent against rat brain butyrylcholinesterase, respectively. Compound 9 (1mg/kg, i.p.) was fully efficacious in reverting scopolamine-induced amnesia in mice. The two active compounds (7 and 9) did not show overt toxic effects at the doses tested in vivo. PMID:15878668

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

    PubMed

    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

    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

  12. Patterns of Population Differentiation and Natural Selection on the Celiac Disease Background Risk

    E-print Network

    Cochran-Stafira, D. Liane

    Patterns of Population Differentiation and Natural Selection on the Celiac Disease Background Risk Biology, Cornell University, Ithaca, New York, United States of America Abstract Celiac disease Selection on the Celiac Disease Background Risk Network. PLoS ONE 8(7): e70564. doi:10.1371/journal

  13. Heterogeneous selection at specific loci in natural environments in Arabidopsis thaliana.

    PubMed Central

    Weinig, Cynthia; Dorn, Lisa A; Kane, Nolan C; German, Zachary M; Halldorsdottir, Solveig S; Ungerer, Mark C; Toyonaga, Yuko; Mackay, Trudy F C; Purugganan, Michael D; Schmitt, Johanna

    2003-01-01

    Genetic variation for quantitative traits is often greater than that expected to be maintained by mutation 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) for fitness traits in the model plant species Arabidopsis thaliana differs among natural ecological settings and genetic backgrounds. At one QTL, the allele that enhanced the viability of fall-germinating seedlings in North Carolina reduced the fecundity of spring-germinating seedlings in Rhode Island. Several other QTL experienced strong directional selection, but only in one site and seasonal cohort. Thus, different loci were exposed to selection in different natural environments. Selection on allelic variation also depended upon the genetic background. The allelic fitness effects of two QTL reversed direction depending on the genotype at the other locus. Moreover, alternative alleles at each of these loci caused reversals in the allelic fitness effects of a QTL closely linked to TFL1, a candidate developmental gene displaying nucleotide sequence polymorphism consistent with balancing selection. Thus, both environmental heterogeneity and epistatic selection may maintain genetic variation for fitness in wild plant species. PMID:14504239

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

    PubMed

    Arnqvist, Göran

    2013-05-01

    Byers and Dunn (Reports, 9 November 2012, p. 802) reported that sexual selection and natural selection are closely related in a wild population of pronghorns. Here, I argue that this conclusion is incorrect. Their main finding is due to the fact that, unsurprisingly, juvenile mortality and juvenile survival are negatively related across years. PMID:23641095

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

    Microsoft Academic Search

    Hiroshi Akashi

    1994-01-01

    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

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

    E-print Network

    Bernatchez, Louis

    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

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

    E-print Network

    Meeden, Lisa A.

    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

  18. 2005 Nature Publishing Group Natural selection on protein-coding genes in the

    E-print Network

    Nielsen, Rasmus

    of different species varies greatly5­16 , with some species, such as Drosophila melanogaster, showing strong, indicating weak negative selection and/or balancing selection operating on mutations at these loci. We find for association mapping studies, because weakly deleterious mutations can reach appreciable frequencies in local

  19. Selected natural phenolic compounds - potential treatment for peripheral neuropathy?

    PubMed

    Smejkal, Karel

    2014-01-01

    Neuropathic pain is a syndrome comprising pain caused by a lesion or dysfunction of the nervous system, or resulting from lesions or diseases of the somatosensory system. Neuropathic pain is often connected with adverse effects of chemotherapy administered because of cancer, infiltration of the nervous tissue with cancer cells, neurodegeneration and diabetes mellitus. Disbalance in the production of various cytokines plays an important role in the pathogenesis of many of the diseases connected with neuropathies. These cytokines comprise in particular interleukins IL-1?, IL-15, and IL-6, tumour necrosis factors, and prostaglandins. The biochemistry of the production of cytokines is directed by nuclear factors, which affect the expression of the mRNA for the respective cytokines or enzymes metabolizing the cytokines. The main nuclear factor which regulates the expression of cytokines is NF-?B. Because of insufficient effectiveness or adverse effects of the pharmacological treatment of peripheral neuropathy, many patients seek supportive or adjuvant therapy. Natural compounds which modulate the production of inflammatory cytokines may reduce the symptoms of neuropathies. Many natural phenolic compounds belong to substances affecting the activity of NF-?B and consequently the activity of cytokines which are regulated by this substance. The aim of this mini-review is to present information about three natural phenols which are potentially usable for the treatment of neuropathies: curcumin, resveratrol and mangiferin, and bring attention to the practical usability thereof. Curcumin and mangiferin are active constituents of plants; they have been used for centuries in traditional medicine. Biological effects of resveratrol have been known for a relatively short time; since the discovery of the so-called French paradox, attention has been focused on resveratrol. This summary includes particularly the information related to the influence on the activity of NF-?B, expression of anti-inflammatory cytokines, and antiradical activity, because imbalance between the creation and degradation of free radicals plays an important role in the activation of NF-?B and in inflammatory processes. It also briefly summarizes basic information concerning bioavailability, metabolism and practical application of the aforementioned substances. Keywords: phenols curcumin mangiferin NF-?B peripheral neuropathy resveratrol. PMID:24870550

  20. Geographical structure and differential natural selection among North European populations

    PubMed Central

    McEvoy, Brian P.; Montgomery, Grant W.; McRae, Allan F.; Ripatti, Samuli; Perola, Markus; Spector, Tim D.; Cherkas, Lynn; Ahmadi, Kourosh R.; Boomsma, Dorret; Willemsen, Gonneke; Hottenga, Jouke J.; Pedersen, Nancy L.; Magnusson, Patrik K.E.; Kyvik, Kirsten Ohm; Christensen, Kaare; Kaprio, Jaakko; Heikkilä, Kauko; Palotie, Aarno; Widen, Elisabeth; Muilu, Juha; Syvänen, Ann-Christine; Liljedahl, Ulrika; Hardiman, Orla; Cronin, Simon; Peltonen, Leena; Martin, Nicholas G.; Visscher, Peter M.

    2009-01-01

    Population structure can provide novel insight into the human past, and recognizing and correcting for such stratification is a practical concern in gene mapping by many association methodologies. We investigate these patterns, primarily through principal component (PC) analysis of whole genome SNP polymorphism, in 2099 individuals from populations of Northern European origin (Ireland, United Kingdom, Netherlands, Denmark, Sweden, Finland, Australia, and HapMap European-American). The major trends (PC1 and PC2) demonstrate an ability to detect geographic substructure, even over a small area like the British Isles, and this information can then be applied to finely dissect the ancestry of the European-Australian and European-American samples. They simultaneously point to the importance of considering population stratification in what might be considered a small homogeneous region. There is evidence from FST-based analysis of genic and nongenic SNPs that differential positive selection has operated across these populations despite their short divergence time and relatively similar geographic and environmental range. The pressure appears to have been focused on genes involved in immunity, perhaps reflecting response to infectious disease epidemic. Such an event may explain a striking selective sweep centered on the rs2508049-G allele, close to the HLA-G gene on chromosome 6. Evidence of the sweep extends over a 8-Mb/3.5-cM region. Overall, the results illustrate the power of dense genotype and sample data to explore regional population variation, the events that have crafted it, and their implications in both explaining disease prevalence and mapping these genes by association. PMID:19265028

  1. Animal genetic resources in Brazil: result of five centuries of natural selection

    Microsoft Academic Search

    A. da S. Mariante; A. A. Egito

    2002-01-01

    Brazil has various species of domestic animals, which developed from breeds brought by the Portuguese settlers soon after their discovery. For five centuries, these breeds have been subjected to natural selection in specific environments. Today, they present characteristics adapted to the specific Brazilian environmental conditions. These breeds developed in Brazil are known as “Crioulo,” “local,” or naturalized. From the beginning

  2. Natural selection on body size is mediated by multiple interacting factors: a comparison of beetle populations

    E-print Network

    Fox, Charles W.

    mediate evolution of body size, are not well understood. For many animals, resource qualityNatural selection on body size is mediated by multiple interacting factors: a comparison of beetle populations varying naturally and experimentally in body size Angela R. Amarillo-Su´arez1 , R. Craig Stillwell

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

    ERIC Educational Resources Information Center

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

    2014-01-01

    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…

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

    Microsoft Academic Search

    Elena Cremenescu; Maria Giurginca; Andrei Giurginca; Aurelia Meghea

    2008-01-01

    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

  5. Parasite mediated selection, sex and diapause in a natural population of Daphnia 

    E-print Network

    Duncan, Alison B

    are common, but explicit examples of parasite-mediated selection in nature are lacking. In this thesis I examine parasite-mediated dynamics in a natural population of Daphnia magna that experiences an annual epidemic of the bacterial pathogen Pasteuria ramosa...

  6. Ant Queen Egg-Marking Signals: Matching Deceptive Laboratory Simplicity with Natural Complexity

    PubMed Central

    van Zweden, Jelle S.; Heinze, Jürgen; Boomsma, Jacobus J.; d'Ettorre, Patrizia

    2009-01-01

    Background Experiments under controlled laboratory conditions can produce decisive evidence for testing biological hypotheses, provided they are representative of the more complex natural conditions. However, whether this requirement is fulfilled is seldom tested explicitly. Here we provide a lab/field comparison to investigate the identity of an egg-marking signal of ant queens. Our study was based on ant workers resolving conflict over male production by destroying each other's eggs, but leaving queen eggs unharmed. For this, the workers need a proximate cue to discriminate between the two egg types. Earlier correlative evidence indicated that, in the ant Pachycondyla inversa, the hydrocarbon 3,11-dimethylheptacosane (3,11-diMeC27) is more abundant on the surface of queen-laid eggs. Methodology We first tested the hypothesis that 3,11-diMeC27 functions as a queen egg-marking pheromone using laboratory-maintained colonies. We treated worker-laid eggs with synthetic 3,11-diMeC27 and found that they were significantly more accepted than sham-treated worker-laid eggs. However, we repeated the experiment with freshly collected field colonies and observed no effect of treating worker-laid eggs with 3,11-diMeC27, showing that this compound by itself is not the natural queen egg-marking pheromone. We subsequently investigated the overall differences of entire chemical profiles of eggs, and found that queen-laid eggs in field colonies are more distinct from worker-laid eggs than in lab colonies, have more variation in profiles, and have an excess of longer-chain hydrocarbons. Conclusions Our results suggest that queen egg-marking signals are significantly affected by transfer to the laboratory, and that this change is possibly connected to reduced queen fertility as predicted by honest signaling theory. This change is reflected in the worker egg policing response under field and laboratory conditions. PMID:19262683

  7. Natural selectivity of Nickel and Vanadium in crude oil

    NASA Astrophysics Data System (ADS)

    Fernandez, Olienka Patricia De La O.

    Nickel and Vanadium have always been found in crude oil all around the world. The metal content is found mainly in porphyrin structures in the asphaltene fraction of the petroleum. In order to determine the reason for this natural preference, a set of experiments testing thermodynamics, kinetics, and other factors were performed. Candidate metalloporphyrins containing Vanadyl, Chromium, Iron, Nickel, Copper and Zinc were analyzed through chemical reactions characterized using Silica Column Chromatography, HPLC, MS and UV-Visible. Theoretical analysis of the stability of metalloporphyrins was conducted using DFT/NRLMOL for computational calculation. The analysis of all factors leads us to conclude that the presence of Nickel and Vanadium in petroleum depend on different factors, not only on the stability of the structures, but mainly on abundance in the medium rising from biological processes.

  8. Affective Neuronal Selection: The Nature of the Primordial Emotion Systems

    PubMed Central

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

    2013-01-01

    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

  9. 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

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

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

    PubMed

    Artacho, Paulina; Nespolo, Roberto F

    2009-04-01

    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

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

    E-print Network

    Lässig, Michael

    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

  13. What can abnormal environments tell us about normal people? Polar stations as natural psychology laboratories.

    PubMed

    Suedfeld, P

    1998-03-01

    The psychological effects of unusual environments reveal different aspects of behaviour from those seen in more customary situations. Such environments provide natural laboratories in which many questions of psychological interest, varying with the specific environment, may be studied. This paper uses isolated polar stations to illustrate this point. In such settings, the usual parameters that control a variety of psychological processes are drastically changed, and confounding variables are stripped away. Consequently, the environment offers unique perspectives on environmental perception and cognition; adaptation to and use of the environment; environmental bonding; social interaction; and coping with environmental challenge. PMID:11541914

  14. SELECTIVE NOx RECIRCULATION FOR STATIONARY LEAN-BURN NATURAL GAS ENGINES

    SciTech Connect

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

    2005-01-01

    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.

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

    E-print Network

    Maria J. Rodriguez

    2010-03-11

    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.

  16. Natural selection in the water: freshwater invasion and adaptation by water colour in the Amazonian pufferfish.

    PubMed

    Cooke, G M; Chao, N L; Beheregaray, L B

    2012-07-01

    Natural selection and ecological adaptation are ultimately responsible for much of the origin of biodiversity. Yet, the identification of divergent natural selection has been hindered by the spatial complexity of natural systems, the difficulty in identifying genes under selection and their relationship to environment, and the confounding genomic effects of time. Here, we employed genome scans, population genetics and sequence-based phylogeographic methods to identify divergent natural selection on population boundaries in a freshwater invader, the Amazonian pufferfish, Colomesus asellus. We sampled extensively across markedly different hydrochemical settings in the Amazon Basin and use 'water colour' to test for ecological isolation. We distinguish the relative contribution of natural selection across hydrochemical gradients from biogeographic history in the origin and maintenance of population boundaries within a single species and across a complex ecosystem. We show that spatially distinct population structure generated by multiple forces (i.e. water colour and vicariant biogeographic history) can be identified if the confounding effects of genetic drift have not accumulated between selective populations. Our findings have repercussions for studies aimed at identifying engines of biodiversity and assessing their temporal progression in understudied and ecologically complex tropical ecosystems. PMID:22551113

  17. 1000 Genomes Selection Browser 1.0: a genome browser dedicated to signatures of natural selection in modern humans

    PubMed Central

    Pybus, Marc; Dall’Olio, Giovanni M.; Luisi, Pierre; Uzkudun, Manu; Carreño-Torres, Angel; Pavlidis, Pavlos; Laayouni, Hafid; Bertranpetit, Jaume; Engelken, Johannes

    2014-01-01

    Searching for Darwinian selection in natural populations has been the focus of a multitude of studies over the last decades. Here we present the 1000 Genomes Selection Browser 1.0 (http://hsb.upf.edu) as a resource for signatures of recent natural selection in modern humans. We have implemented and applied a large number of neutrality tests as well as summary statistics informative for the action of selection such as Tajima’s D, CLR, Fay and Wu’s H, Fu and Li’s F* and D*, XPEHH, ?iHH, iHS, FST, ?DAF and XPCLR among others to low coverage sequencing data from the 1000 genomes project (Phase 1; release April 2012). We have implemented a publicly available genome-wide browser to communicate the results from three different populations of West African, Northern European and East Asian ancestry (YRI, CEU, CHB). Information is provided in UCSC-style format to facilitate the integration with the rich UCSC browser tracks and an access page is provided with instructions and for convenient visualization. We believe that this expandable resource will facilitate the interpretation of signals of selection on different temporal, geographical and genomic scales. PMID:24275494

  18. 113 Lab Learning Objectives Week 13: Information and Natural Selection lab #8

    E-print Network

    Campbell, A. Malcolm

    of evolution based on lab experiences. · Explain how antibiotic resistant bacteria can appear quickly in the population. · Design directed evolution process to select antibiotic resistant bacteria. · Formulate an hypothesis how antibiotic resistant bacteria evolve outside the laboratory. · Propose a mechanism that allows

  19. Chemical composition of selected core samples, Idaho National Engineering Laboratory, Idaho

    SciTech Connect

    Knobel, L.L.; Cecil, L.D.; Wood, T.R.

    1995-11-01

    This report presents chemical compositions determined from 84 subsamples and 5 quality-assurance split subsamples of basalt core from the eastern Snake River Plain. The 84 subsamples were collected at selected depths from 5 coreholes located on the Idaho National Engineering Laboratory, Idaho. This report was jointly prepared by Lockheed Idaho Technologies Company and the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, Idaho Operations Office. Ten major elements and as many as 32 trace elements were determined for each subsample either by wavelength dispersive X-ray fluorescence spectrometry, inductively coupled plasma mass spectrometry, or by both methods. Descriptive statistics for each element were calculated and tabulated by analytical method for each corehole.

  20. Natural selection on quantitative immune defence traits: a comparison between theory and data.

    PubMed

    Seppälä, O

    2015-01-01

    Parasites present a threat for free-living species and affect several ecological and evolutionary processes. Immune defence is the main physiological barrier against infections, and understanding its evolution is central for predicting disease dynamics. I review theoretical predictions and empirical data on natural selection on quantitative immune defence traits in the wild. Evolutionary theory predicts immune traits to be under stabilizing selection owing to trade-offs between immune function and life-history traits. Empirical data, however, support mainly positive directional selection, but also show variation in the form of selection among study systems, immune traits and fitness components. I argue that the differences between theory and empirical data may at least partly arise from methodological difficulties in testing stabilizing selection as well as measuring fitness. I also argue that the commonness of positive directional selection and the variation in selection may be caused by several biological factors. First, selection on immune function may show spatial and temporal variation as epidemics are often local/seasonal. Second, factors affecting the range of phenotypic variation in immune traits could alter potential for selection. Third, different parasites may impose different selective pressures depending on their characteristics. Fourth, condition dependence of immune defence can obscure trade-offs related to it, thus possibly modifying observed selection gradients. Fifth, nonimmunological defences could affect the form of selection by reducing the benefits of strong immune function. To comprehensively understand the evolution of immune defence, the role of above factors should be considered in future studies. PMID:25400248

  1. Chemo- and Site-Selective Derivatizations of Natural Products Enabling Biological Studies

    PubMed Central

    Robles, Omar

    2014-01-01

    Bioactive natural products and derivatives remain an enduring starting point for the discovery of new cellular targets for disease intervention and lead compounds for the development of new therapeutic agents. The former goal is accomplished through the synthesis of bioactive cellular probes from natural products enabling insights into the mechanism of action of these natural products by classical affinity chromatography or more recent proteome profiling methods. However, the direct and selective modification of native natural products for these purposes remains a challenge due to the structural complexity and the wide functional group diversity found in these natural substances. The lack of selective synthetic methods available to directly manipulate unprotected complex small molecules, in particular to perform structure-activity relationship studies and prepare appropriate cellular probes, has recently begun to be addressed benefitting from the broader emerging area of chemoselective synthetic methodology. Thus, new reagents, catalysts and reaction processes are enabling both chemo- and site-selective modifications of complex, native natural products. In this review, we describe selected recent examples of these functionalization strategies in this emerging area. PMID:24468713

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

    SciTech Connect

    Pawloski, G A

    2011-02-28

    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.

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

    PubMed Central

    Okazawa, Gouki; Tajima, Satohiro; Komatsu, Hidehiko

    2015-01-01

    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

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

    PubMed

    Mercado, Jesús M; Gordillo, F J L

    2011-09-01

    Most of the experimental work on the effects of ocean acidification on the photosynthesis of algae has been performed in the laboratory using monospecific cultures. It is frequently assumed that the information obtained from these cultures can be used to predict the acclimation response in the natural environment. CO(2) concentration is known to regulate the expression and functioning of the CCMs in the natural communities; however, ambient CO(2) can become quite variable in the marine ecosystems even in the short- to mid-term. We propose that the degree of saturation of the photosynthesis for a given algal community should be defined in relation to the particular characteristics of its habitat, and not only in relation to its taxonomic composition. The convenience of high CO(2) experiments to infer the degree of photosynthesis saturation by CO(2) in the natural algal communities under the present ocean conditions, as well as its trend in a coming future is discussed taking into account other factors such as the availability of light and nutrients, and seasonality. PMID:21445608

  5. The build up of mutation-selection- drift balance in laboratory Drosophila populations.

    PubMed

    García-Dorado, Aurora; Avila, Victoria; Sánchez-Molano, Enrique; Manrique, Antonio; López-Fanjul, Carlos

    2007-03-01

    The build up of an equilibrium between mutation, selection, and drift in populations of moderate size is an important evolutionary issue, and can be critical in the conservation of endangered populations. We studied this process in two Drosophila melanogaster populations initially lacking genetic variability (C1 and C2) that were subsequently maintained during 431 or 165 generations with effective population size N(e) approximately 500 (estimated by lethal complementation analysis). Each population originated synchronously to a companion set of full-sib mutation accumulation (MA) lines, C1 and MA1 were derived from an isogenic origin and C2 and MA2 from a single MA1 line at generation 265. The results suggest that both C1 and C2 populations were close to the mutation-selection-drift balance for viability and bristle traits, and are consistent with a 2.5-fold increase of the mutation rate in C2 and MA2. Despite this increase, the average panmictic viability in C2 was only slightly below that of C1, indicating that the expressed loads due to segregating deleterious mutation were small, in agreement with the low deleterious mutation rate (0.015-0.045) previously reported for the MA1 lines. In C1, the nonlethal inbreeding depression rate for viability was 30% of that usually estimated in segregating populations. The genetic variance for bristles regenerated in C1 and C2 was moderately smaller than the average value reported for natural populations, implying that they have accumulated a substantial adaptive potential. In light of neutral and selective predictions, these results suggest that bristle additive variance was predominantly due to segregation of mutations with deleterious effects of the order of 10(-3), and is consistent with relatively weak causal stabilizing selection (V(s) approximately 30). PMID:17348928

  6. How relevant are house dust mite-fungal interactions in laboratory culture to the natural dust system?

    PubMed

    Hay, D B; Hart, B J; Pearce, R B; Kozakiewicz, Z; Douglas, A E

    1992-11-01

    Both house dust and house dust mites Dermatophagoides pteronyssinus contained a wider range of fungi than laboratory mite cultures. In total, nine species of fungi were isolated from D. pteronyssinus in house dust, and these included three xerophilic species (Eurotium amstelodami, Aspergillus penicillioides and Wallemia sebi) commonly found in laboratory cultures of D. pteronyssinus. It is concluded that mites do interact with a similar range of fungi in natural dust and in laboratory culture, but that the diversity of fungal species in the laboratory is reduced and the density of individual fungal species in culture exceeds that of house dust. In a second experiment, dust samples were incubated at room temperature with 75% relative humidity. The diversity of fungi invariably declined from up to 13 genera to the few species recorded in laboratory culture. This suggests that the dominance of xerophilic fungi in laboratory mite rearings is mediated primarily by low relative humidity, and the exclusion of air-borne spores. PMID:1493747

  7. Synergism of natural selection and introgression in the origin of a new species.

    PubMed

    Grant, Peter R; Grant, B Rosemary

    2014-05-01

    This article explores how introgressive hybridization enhances the evolutionary effects of natural selection and how, reciprocally, natural selection can enhance the evolutionary effects of introgression. Both types of interaction were observed during a 40-year study of Darwin's finches (Geospiza) on the small Galápagos island of Daphne Major. Hybrids, produced rarely by Geospiza fortis (medium ground finch) breeding with Geospiza scandens (cactus finch) and Geospiza fuliginosa (small ground finch), survived and bred as well as the parental species in the past 3 decades. By backcrossing, they increased the standing genetic variation and thereby the evolutionary responsiveness of the populations to natural selection. Natural selection occurred in droughts and oscillated in direction as a result of climatically induced fluctuations in food composition. Introgressive hybridization has led to the formation of a new lineage. It was initiated by a large, introgressed, hybrid male with a unique song and genetic marker that immigrated from the nearby island of Santa Cruz and bred with local hybrids and with G. fortis. All members of the lineage died in the 2003-2005 drought except a brother and a sister, who then bred with each other. Subsequent increase in the lineage was facilitated by selective mortality of the largest G. fortis. Breeding endogamously, the lineage is behaving as a biological species. PMID:24739199

  8. Upgrading low-quality natural gas with H 2S- and CO 2-selective polymer membranes

    Microsoft Academic Search

    J. Hao; P. A. Rice; S. A. Stern

    2008-01-01

    The cost of membrane separation processes for removing CO2 and H2S from low-quality natural gas can be reduced for some concentration ranges of CO2 and H2S by utilizing concurrently two different types of polymer membranes, one with a high CO2\\/CH4 selectivity and the other with a high H2S\\/CH4 selectivity. The polymers considered in this exploratory study were 6FDA-HAB polyimide for

  9. Interactions between sexual and natural selection on the evolution of a plumage badge

    Microsoft Academic Search

    Brian J. Olsen; Russell Greenberg; Irene A. Liu; Joshua M. Felch; Jeffrey R. Walters

    2010-01-01

    The evolutionary stability of signals varies due to interactions between sexual and natural selection. A tidal-marsh sparrow,\\u000a Melospiza georgiana nigrescens, possesses darker pigmentation than an inland-marsh sparrow, M. g. georgiana. Studies of feather-degrading bacteria and convergent evolution among salt-marsh vertebrates suggest this dark coloration\\u000a is due to environmental selection. Sexually dichromatic swamp sparrow crowns, however, may be additionally under sexual

  10. NATURAL SELECTION AND FITNESS ENTROPY IN A DENSITY-REGULATED POPULATION

    Microsoft Academic Search

    R. A. DESHARNAISI; R. F. COSTANTINOZ

    1982-01-01

    The entropy H(p,,p*) of a population with the initial allele frequency po given the equilibrium polymorphic frequency p* has been proposed as a measure of natural selection. In the present paper, we have extended this concept to include a particular aspect of density-dependent selection. We compared size trajectory of a population initially at genetic equilibrium, h(t), with the size trajectories

  11. Upgrading low-quality natural gas with H 2S- and CO 2-selective polymer membranes

    Microsoft Academic Search

    J. Hao; P. A. Rice; S. A. Stern

    2002-01-01

    The upgrading of low-quality natural gas by membrane separation processes utilizing two different types of polymer membranes was investigated by process design, optimization, and economic assessment studies. The membranes considered for these processes exhibit high CO2\\/CH4 and H2S\\/CH4 selectivities, respectively. Low-quality natural gas was simulated by ternary CH4\\/CO2\\/H2S mixtures containing up to 40mol% CO2 and 10mol% H2S. The membrane processes

  12. Pollen limitation and natural selection on floral characters in the yellow monkeyflower, Mimulus guttatus.

    PubMed

    Fishman, Lila; Willis, John H

    2008-01-01

    In flowering plants, pollen limitation has been proposed to intensify selection on floral characters important in pollinator attraction, but may also select for traits that increase seed set through autonomous selfing. Here, a factorial design (+/- pollen addition, +/- pollinator removal) was used to investigate how the pollination environment affects selection on floral morphology via female fitness in a mixed-mating population of the yellow monkeyflower, Mimulus guttatus (Phrymaceae). Female fitness was strongly pollen-limited, with supplementally pollinated plants setting 37% more seeds than open-pollinated individuals. Strong positive selection was found on flower length, weak positive selection on flower width : length ratio and no selection on stigma-anther distance in both open-pollinated and supplementally pollinated treatments. By contrast, flowers with relatively narrow corollas and low stigma-anther distances were favored in the pollinator exclusion treatment. These results provide mixed support for the idea that pollen limitation intensifies selection on floral characters. Despite strong phenotypic selection, natural pollen limitation did not mediate selection on characters associated with either pollinator attraction or self-fertilization. However, the novel pattern of selection on severely pollen-limited plants suggests that reproductive assurance against pollinator loss may have been directly involved in the floral evolution of closely related selfing taxa. PMID:18005321

  13. Imprints of Natural Selection Along Environmental Gradients in Phenology-Related Genes of Quercus petraea

    PubMed Central

    Alberto, Florian J.; Derory, Jérémy; Boury, Christophe; Frigerio, Jean-Marc; Zimmermann, Niklaus E.; Kremer, Antoine

    2013-01-01

    We explored single nucleotide polymorphism (SNP) variation in candidate genes for bud burst from Quercus petraea populations sampled along gradients of latitude and altitude in Western Europe. SNP diversity was monitored for 106 candidate genes, in 758 individuals from 32 natural populations. We investigated whether SNP variation reflected the clinal pattern of bud burst observed in common garden experiments. We used different methods to detect imprints of natural selection (FST outlier, clinal variation at allelic frequencies, association tests) and compared the results obtained for the two gradients. FST outlier SNPs were found in 15 genes, 5 of which were common to both gradients. The type of selection differed between the two gradients (directional or balancing) for 3 of these 5. Clinal variations were observed for six SNPs, and one cline was conserved across both gradients. Association tests between the phenotypic or breeding values of trees and SNP genotypes identified 14 significant associations, involving 12 genes. The results of outlier detection on the basis of population differentiation or clinal variation were not very consistent with the results of association tests. The discrepancies between these approaches may reflect the different hierarchical levels of selection considered (inter- and intrapopulation selection). Finally, we obtained evidence for convergent selection (similar for gradients) and clinal variation for a few genes, suggesting that comparisons between parallel gradients could be used to screen for major candidate genes responding to natural selection in trees. PMID:23934884

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

    PubMed

    Kulpa, Sarah M; Leger, Elizabeth A

    2013-04-01

    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

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

    PubMed Central

    Kulpa, Sarah M; Leger, Elizabeth A

    2013-01-01

    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

  16. Natural Selection

    ERIC Educational Resources Information Center

    Hall, Julie

    2006-01-01

    For education administrators, summer break is the time to regroup and prepare facilities for the next influx of students. Ensuring that facilities are equipped with proper furnishings is part of this preparation. Through careful research and planning, education administrators can choose furniture that will become a lasting investment. This article…

  17. Natural Selection

    NSDL National Science Digital Library

    The Concord Consortium

    2011-12-11

    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.

  18. Elimination of laboratory-acquired cadmium by the oyster Crassostrea virginica in the natural environment

    SciTech Connect

    Mowdy, D.E.

    1981-03-01

    Many productive shellfish-growing areas along the coast of the United States are closed because of pollution from domestic and industrial wastes. Many estuarine areas that are closed to shellfish harvesting because of bacterial pollution contain productive shellfish beds. These shellfish can be used as commercial food products after they have been relayed to approved growing waters and allowed to eliminate the polluting organisms. Relaying is not presently applied to shellfish contaminated with toxic metals for several reasons: There are no standards to control metal pollution (other than mercury) in seafood; few public health problems in this country involve toxic levels of trace metals in oysters; and not enough information is available to indicate the feasibility of such a project. This study demonstrates the feasibility of relaying cadmium-contaminated oysters to observe cadmium elimination. Because oysters containing naturally acquired cadmium were not readily available, oysters containing laboratory-incurred cadmium were studied.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

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

    USGS Publications Warehouse

    Gomberg, J.; Schulz, W.; Bodin, P.; Kean, J.

    2011-01-01

    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.

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

    USGS Publications Warehouse

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

    2014-01-01

    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.

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

    PubMed

    Farag, Aïda M; Harper, David D; Skaar, Don

    2014-09-01

    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 NaHCO(3) rise to more than 1500?mg/L (also expressed as >1245?mg HCO(3) (-) /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. PMID:24909548

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

    PubMed Central

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

    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.

  5. Using a semi-natural stream to produce young sturgeons for conservation stocking: Maintaining natural selection during spawning and rearing

    USGS Publications Warehouse

    Kynard, B.; Pugh, D.; Parker, T.; Kieffer, M.

    2011-01-01

    Young sturgeons used for conservation stocking are presently produced using the same methods used for commercial culture. To determine if young sturgeons could be produced without relaxing natural selection factors, we developed a semi-natural stream where we annually studied mating of wild shortnose sturgeon (Acipenser brevirostrum) observed movement of gametes released freely during spawning, and estimated the number of larvae produced by various densities of spawned eggs. The stream had a bottom area of 18.8m2, a rubble-gravel bottom, and a mean bottom current at 0.6 depth during spawning of 48cms-1 (range, 17-126cms-1). Wild adults successfully spawned in the stream each year for 7years (2002-2008). Some females and males were more successful during spawning than others, suggesting an unequal fitness during spawning among wild individuals, which is different than the controlled spawning fitness of individuals in hatcheries. Male and female gametes spawned naturally must connect quickly in the fast current or fail, a selection factor absent in hatcheries. The number of larvae produced was inversely related to spawned egg densitym-2 (R2=0.65) and the maximum number of larvae produced was 8000-16000 (425-851larvaem-2 of bottom). Artificial spawning streams have the potential to contribute to sturgeon restoration. ?? 2011 Blackwell Verlag, Berlin.

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

    PubMed

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

    2014-11-01

    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

  7. 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...

  8. The size of beaks of Darwin's finches on the Galpagos Islands is influenced by natural selection.

    E-print Network

    Emlen, Douglas J.

    The size of beaks of Darwin's finches on the Galápagos Islands is influenced by natural selection rates of fish populations. Charles Darwin managedto visit only a handful of the Galápa- gos Islands the process that Darwin and Wallace first proposed over 150 years ago. In this chapter we'll consider a wide

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

    Microsoft Academic Search

    L. B ERNATCHEZ; C. L ANDRY

    2003-01-01

    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,

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

    Microsoft Academic Search

    John Sweller

    2004-01-01

    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.

  11. 2002 Nature Publishing Group Selective cell suicide is crucial for sculpting the embryo,

    E-print Network

    Gauthier, Eric

    © 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

  12. Natural Selection Affects Multiple Aspects of Genetic Variation at Putatively Neutral Sites across the Human Genome

    Microsoft Academic Search

    Kirk E. Lohmueller; Anders Albrechtsen; Yingrui Li; Su Yeon Kim; Thorfinn Korneliussen; Nicolas Vinckenbosch; Geng Tian; Emilia Huerta-Sanchez; Alison F. Feder; Niels Grarup; Torben Jørgensen; Tao Jiang; Daniel R. Witte; Annelli Sandbæk; Ines Hellmann; Torsten Lauritzen; Torben Hansen; Oluf Pedersen; Jun Wang; Rasmus Nielsen

    2011-01-01

    A major question in evolutionary biology is how natural selection has shaped patterns of genetic variation across the human genome. Previous work has documented a reduction in genetic diversity in regions of the genome with low recombination rates. However, it is unclear whether other summaries of genetic variation, like allele frequencies, are also correlated with recombination rate and whether these

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

    ERIC Educational Resources Information Center

    Sweller, John

    2004-01-01

    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…

  14. Variation in resource limitation of plant reproduction influences natural selection on floral traits of Asclepias syriaca

    Microsoft Academic Search

    Christina M. Caruso; Davin L. D. Remington; Kate E. Ostergren

    2005-01-01

    The availability of both pollen and resources can influence natural selection on floral traits, but their relative importance in shaping floral evolution is unclear. We experimentally manipulated pollinator and resource (fertilizer and water) availability in the perennial wildflower Asclepias syriaca L. Nine floral traits, one male fitness component (number of pollinia removed), and two female fitness components (number of pollinia

  15. Studying the Genetics of Behavior and Evolution by Adaptation and Natural Selection.

    ERIC Educational Resources Information Center

    Silverman, Jules

    1998-01-01

    Provides an exercise designed to give students an appreciation for the genetic basis of behavior. Employs the phenomenon of glucose aversion as an example of evolution by mutation and accelerated natural selection, thereby revealing one of the ways in which organisms adapt to human interference. (DDR)

  16. Developing Conceptual Understanding of Natural Selection: The Role of Interest, Efficacy, and Basic Prior Knowledge

    ERIC Educational Resources Information Center

    Linnenbrink-Garcia, Lisa; Pugh, Kevin J.; Koskey, Kristin L. K.; Stewart, Victoria C.

    2012-01-01

    Changes in high school students' (n = 94) conceptions of natural selection were examined as a function of motivational beliefs (individual interest, academic self-efficacy), basic prior knowledge, and gender across three assessments (pre, post, follow-up). Results from variable-centered analyses suggested that these variables had relatively little…

  17. Unweaving Misconceptions: Guided Learning, Simulations, and Misconceptions in Learning Principles of Natural Selection

    ERIC Educational Resources Information Center

    Weeks, Brian E.

    2013-01-01

    College students often come to the study of evolutionary biology with many misconceptions of how the processes of natural selection and speciation occur. How to relinquish these misconceptions with learners is a question that many educators face in introductory biology courses. Constructivism as a theoretical framework has become an accepted and…

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

    E-print Network

    A. Barrau

    2007-02-09

    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.

  19. Influences of Teleological and Lamarckian Thinking on Student Understanding of Natural Selection

    ERIC Educational Resources Information Center

    Stover, Shawn K.; Mabry, Michelle L.

    2007-01-01

    Previous research has demonstrated creationist, Lamarckian, and teleological reasoning in high school and college students. These lines of thinking conflict with the Darwinian notion of natural selection, which serves as the primary catalyst for biological evolution. The current study assessed evolutionary conceptions in non-science majors,…

  20. Reasoning about Natural Selection: Diagnosing Contextual Competency Using the ACORNS Instrument

    ERIC Educational Resources Information Center

    Nehm, Ross H.; Beggrow, Elizabeth P.; Opfer, John E.; Ha, Minsu

    2012-01-01

    Studies of students' thinking about natural selection have revealed that the scenarios in which students reason evoke different types, magnitudes, and arrangements of knowledge elements and misconceptions. Diagnostic tests are needed that probe students' thinking across a representative array of evolutionary contexts. The ACORNS is a diagnostic…

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

    ERIC Educational Resources Information Center

    Nehm, Ross H.; Haertig, Hendrik

    2012-01-01

    Our study examines the efficacy of Computer Assisted Scoring (CAS) of open-response text relative to expert human scoring within the complex domain of evolutionary biology. Specifically, we explored whether CAS can diagnose the explanatory elements (or Key Concepts) that comprise undergraduate students' explanatory models of natural selection with…

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

    Microsoft Academic Search

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

    2002-01-01

    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

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

    ERIC Educational Resources Information Center

    Beachly, William

    2010-01-01

    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…

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

    Microsoft Academic Search

    Peter S. White; Joan L. Walker

    1997-01-01

    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

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

    ERIC Educational Resources Information Center

    Nehm, Ross H.; Schonfeld, Irvin Sam

    2010-01-01

    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…

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

    ERIC Educational Resources Information Center

    Nola, Robert

    2013-01-01

    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…

  7. Genetic Programming as a Means for Programming Computers by Natural Selection

    E-print Network

    Fernandez, Thomas

    Genetic Programming as a Means for Programming Computers by Natural Selection JOHN R. KOZA Computer can be viewed as requiring the discovery of a computer program that produces some desired output to searching a space of possible computer programs for a highly fit individual computer program. The recently

  8. Student Conceptions of Natural Selection and Its Role in Evolution, Research Series No. l65.

    ERIC Educational Resources Information Center

    Bishop, Beth A.; Anderson, Charles W.

    Pretests and posttests on the topic of evolution through natural selection were administered to students in a college nonmajors' biology course. Analysis of test responses revealed that most students understood evolution as a process in which species respond to environmental conditions by changing gradually over time. Student thinking differed…

  9. Sex, death and genetic variation: natural and sexual selection on cricket song

    E-print Network

    Gray, David A.

    Sex, death and genetic variation: natural and sexual selection on cricket song David A. Gray1 Male ¢eld crickets, Gryllus integer, in Texas, USA, produce a trilled calling song that attracts female crickets, resulting in enhanced mating success. Gravid female parasitoid £ies, Ormia ochracea

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

    ERIC Educational Resources Information Center

    Royer, Anne M.; Schultheis, Elizabeth H.

    2014-01-01

    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…

  11. PREDICTING THE FIELD RESISTANCE TO POWDERY MILDEW OF GRAPEVINE SELECTIONS BASED ON THE LABORATORY TESTING OF YOUNG VINES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of this work is to improve the speed and accuracy of the identification of powdery mildew (caused by Uncinula necator ) resistance in grapevine for breeding purposes. Fifty-seven selections were evaluated. Tests were done to determine the accuracy of laboratory leaf disk inoculati...

  12. 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

    Elliott, Shannon Snyder

    2007-01-01

    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…

  13. An Experimental Comparison of Direct-Detailed Versus Directed Discovery Laboratory Exercises in Teaching Selected Elements of Basic Electricity.

    ERIC Educational Resources Information Center

    Brenner, Charles J.

    The purpose of this study was to ascertain the ef"ects of direct-detailed and directed discovery laboratory methods on selected behavior characteristics of college students during a 3-week period. The 120 students wer" enrolled in three sections of an electricity course under three teachers. During the first 3 weeks of the experiment, 20 students…

  14. Selective molecular sequestration with concurrent natural product functionalization and derivatization: from crude natural product extracts to a single natural product derivative in one step.

    PubMed

    Krch?ák, Viktor; Zají?ek, Jaroslav; Miller, Patricia A; Miller, Marvin J

    2011-12-16

    A resin-bound nitroso compound sequestered a single unexpected component from crude plant seed extracts. Several plants, including Piper nigrum, Eugenia caryophyllata, and Pimenta dioica, were extracted with organic solvent in the presence of a nitroso-containing resin. The nitroso resin selectively sequestered a single compound, ?-caryophyllene, via a chemo- and regioselective ene reaction. The ene product was released from the resin, and proper selection of the solid-phase linker and cleavage cocktail allowed concomitant further transformation of the primary ene product to a novel functionalized polycycle. Preliminary studies indicate that the new hydroxylamine-containing natural product derivatives have antibiotic activity. PMID:22059469

  15. Selective Molecular Sequestration with Concurrent Natural Product Functionalization and Derivatization: From Crude Natural Product Extracts to a Single Natural Product Derivative in One Step

    PubMed Central

    Krch?ák, Viktor; Zají?ek, Jaroslav; Miller, Patricia A.; Miller, Marvin J.

    2011-01-01

    A resin-bound nitroso compound sequestered a single unexpected component from crude plant seed extracts. Several plants, including Piper nigrum, Eugenia caryophyllata, and Pimenta dioica, were extracted with organic solvent in the presence of a nitroso-containing resin. The nitroso resin selectively sequestered a single compound, ?-caryophyllene, via a chemo and regioselective ene reaction. The ene product was released from the resin and proper selection of the solid-phase linker and cleavage cocktail allowed concomitant further transformation of the primary ene product to a novel functionalized polycycle. Preliminary studies indicate that the new hydroxylamine-containing natural product derivatives have antibiotic activity. PMID:22059469

  16. Examining beginning biology teachers' knowledge, beliefs, and practice for teaching natural selection

    NASA Astrophysics Data System (ADS)

    Sickel, Aaron J.

    The teacher is the most important school-based factor in student learning. Thus, in order to improve student learning, we must examine how teachers learn to teach. My overarching research agenda centers upon K-16 science teacher learning and development. Within this agenda, I conduct studies focused on two strands of research: 1) How teachers learn to teach science using constructivist and inquiry-oriented teaching strategies; and 2) How teachers learn to teach biological evolution. This dissertation merges the two strands together, and consists of four related manuscripts that address how beginning biology teachers learn to teach natural selection using constructivist and inquiry-oriented teaching strategies. In the first manuscript, I reviewed the evolution education literature focused on K-12 teachers’ knowledge, beliefs, and practice for teaching evolution. Based upon findings across the studies, I articulated five goals for preparing teachers to teach evolution. The second and third manuscripts are longitudinal empirical studies focused on three beginning biology teachers learning to teach natural selection using the 5E instructional model and interactive classroom simulations. The fourth manuscript is a practitioner article that explains how to teach natural selection simulations using a constructivist, analogy-based teaching strategy. Findings that cut across the four manuscripts are organized into the following themes: (A) The participants developed some common types of knowledge for teaching natural selection, yet also developed in unique ways. All participants developed knowledge of the horizontal curriculum. Yet, participants also developed different types of knowledge. For example, participants who had taken an evolution course developed more integrated pedagogical content knowledge for teaching the core concepts of natural selection. The participant who integrated discipline-level knowledge for teaching science through inquiry with topic-level knowledge for teaching natural selection had taken an undergraduate evolution course and possessed a student-centered orientation, demonstrating the importance of both subject matter preparation and orientations for teaching science in reform-based ways. Differences I observed among the participants highlight the need for more in-depth case studies in addition to large-scale studies to understand beginning science teacher development. (B) Beliefs about science teaching and learning shaped the participants’ knowledge and practice for teaching natural selection. Participants who possessed student-centered science teaching orientations developed more integrated pedagogical content knowledge for teaching natural selection. However, one participant with a student-centered orientation possessed beliefs in which it was the students’ role to discover natural selection with little intervention from the teacher. This finding supports the need to help teachers develop constructivist orientations to facilitate students’ conceptual understandings of science in addition to engaging in inquiry processes. (C) Learning to teach evolution requires a complex amalgam of knowledge, beliefs, and practice. The literature highlights the types of knowledge and beliefs that teachers must develop to be willing to teach evolution, including content knowledge, understandings of the nature of science, and knowledge of teaching controversial topics. In addition, teachers need to develop pedagogical content knowledge for teaching evolution in ways that support students’ conceptual understanding of evolution. Based upon my review of the literature, secondary science majors should be required to take a course designed for teaching evolution, with the following goals: 1) Develop content knowledge of evolution; 2) Accept evolution as scientifically valid; 3) Develop understandings of the nature of science related to evolution; 4) Develop strategies for handling the public controversy; and 5) Develop pedagogical content knowledge for teaching evolution. This collection of work has implications f

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

    PubMed

    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

    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

  18. Effect of reproduction on the consistency of the between-line type divergence in laboratory mice selected on Basal metabolic rate.

    PubMed

    Sadowska, Julita; G?bczy?ski, Andrzej K; Konarzewski, Marek

    2015-01-01

    Artificial selection experiments are an effective tool for testing evolutionary hypotheses, because they allow one to separate genetic and environmental variances of the phenotype. However, it is unclear whether trait divergence typically selected early in life persists over an animal's life and altered physiological states, such as reproduction. Here we analyzed the long-term consistency of the between-line type divergence in basal metabolic rate (BMR) selected at 12 wk of age in laboratory mice. We measured BMR in nonreproducing and reproducing females at the age of 22 wk and then at 27 wk of age. Our results show that within both the reproducing group and the control group, the between-line type separation in BMR is consistently retained over time and reproductive status. Metabolically active internal organs (heart, liver, kidneys, and small intestine) also consistently differed in size between the two line types with no significant long-term effect of reproduction. The observed consistency of the between-line type divergence in BMR suggests the existence of the persistent effect of the selection on metabolic traits applied early in life. Moreover, BMR variation achieved by means of artificial selection is considerably higher than that found in natural/unmanipulated populations. The latter may therefore be characterized by insufficient variance to statistically resolve correlations involving BMR. PMID:25860830

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

    PubMed

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

    2003-10-01

    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

  20. An example of a natural laboratory for studying the microstructural and petrophysical properties in mylonitic leucogneiss

    NASA Astrophysics Data System (ADS)

    Punturo, Rosalda; Cirrincione, Rosolino; Fazio, Eugenio; Heilbronner, Renée.; Kern, Hartmut; Mengel, Kurt; Ortolano, Gaetano; Pezzino, Antonino

    2010-05-01

    In the southern border of the Calabrian Peloritani Orogen (southern Italy) near to the mount Montalto, a thick alpine shear zone crops out interposed between two units: the Aspromonte Unit at the top and the Madonna di Polsi Unit at the bottom, respectively. The crustal-scale shear zone involves different rock types of these two units and can be considered as a natural laboratory for studying the changes in microstructural features and elastic properties of progressively deformed mylonitic rocks. In order to evaluate the relationship between rock fabric and seismic anisotropy, we collected a suite of myonitic leucogneiss belonging to the Aspromonte Unit. They are mostly made up of Qtz+Ab+Wm+Kfs together with subordinate amounts of Bt+Ep+Chl+Tur. The texture of these leucocratic gneisses ranges from weakly deformed mylonite to ultramylonite; the progressive mylonitization is demonstrated by decreasing in grain-size of the pre-kinematic porphyroclasts associated with increase in SPO and syn-mylonitic growth of high phengite white mica and plagioclase albitization. We present here the results of an integrated microstructural study which combines both modern and classical techniques (e.g. C.I.P. method and U-stage approach) and petrophysical investigation consisting of laboratory seismic measurements at various pressure conditions (up to 600MPa) as well as calculations of elastic properties of the mylonitc rock considered as a poly-mineral and poly-crystalline aggregate. Our data suggest that a close relationship exists between bulk seismic anisotropy and petrofabric features. The most important consideration that we can set out is that the mineralogical changes, together with the strain partitioning, are the main factors responsible for the changes in elastic properties observed in the studied mylonitic leucogneiss during the progressive deformation.

  1. Selection of natural Gas Fired Advanced Turbine Systems (GFATS) program - Task 3. Topical report

    SciTech Connect

    NONE

    1994-06-01

    Research continued on natural gas-fired turbines.The objective of Task 3 was to perform initial trade studies and select one engine system (Gas-Fired Advanced Turbine System [GFATS]) that the contractor could demonstrate, at full scale, in the 1998 to 2000 time frame. This report describes the results of the selection process. This task, including Allison internal management reviews of the selected system, has been completed. Allison`s approach to ATS is to offer an engine family that is based on the newest T406 high technology engine. This selection was based on a number of parameters including return on investment (ROI), internal rate of return (IRR) market size and potential sales into that market. This base engine family continues a history at Allison of converting flight engine products to industrial use.

  2. West Florida Shelf: A natural laboratory for the study of ocean acidificiation

    USGS Publications Warehouse

    Hallock, Pamela; Robbins, Lisa L.; Larson, Rebekka A.; Beck, Tanya; Schwing, Patrick; Martinez-Colon, Michael; Gooch, Brad

    2010-01-01

    Declining oceanic pH and carbonate-ion concentrations are well-known consequences of increased atmospheric and surface-ocean partial pressure of carbon dioxide (pCO2). The possible subject of shifts in seawater carbonate chemistry on biocalcification and survival rates of marine organisms provides questions amenable to both experimental and field study (Kleypas and Langdon, 2006). To date, limited quantitative data exist with which to formalize and test hypotheses regarding such impacts, particularly in continental-shelf settings. The continental shelves of Florida provide an ideal natural laboratory in which to test latitudinal (and temperature and depth) shifts in habitat ranges of calcifying organisms. Both the east and west Florida shelves extend from warm temperate to subtropical latitudes; additionally, the west Florida shelf has very little siliciclastic influx to mask the carbonate production. This study utilizes the natural laboratory of the west and southwest Florida shelf (fig 1.1) to examine the transition from foramol (predominately foraminifera and molluscan) carbonate sediments, characteristic of the west-central Florida shelf, to chlorozoan (algal and coral) sediments characteristic of the southwest Florida shelf. The west Florida shelf is a mixed siliciclastic carbonate ramp that to the south transitions to the carbonate-dominated southwest Florida shelf (Enos, 1977; Brooks and others, 2003). The west Florida shelf is a distally steepened carbonate ramp that is ~250 kilometers (km) wide (Read, 1985). It is covered by a veneer of unconsolidated sediment consisting of mainly biogenic carbonate and quartz in the near shore, with subordinate amounts of phosphate. The sediment-distribution pattern is largely a function of proximity to source, with physical processes playing a minor role in distribution. The carbonate sand-and-gravel fraction is produced by organisms within the depositional basin of the west Florida shelf (Brooks and others, 2003). The southwest Florida shelf is a rimmed carbonate margin where organisms produce virtually all of the substrate; it also exhibits a greater sediment thickness as compared to the west Florida shelf (Enos, 1977). Temperature, which is usually associated with latitude, plays a major role in locations of foramol versus chlorozoan assemblages, but other factors beyond latitude influence temperature on the west and southwest Florida shelves. The potential of cooler, deep-water upwelling and transport over the bottom waters of the shelf may have a significant role in the species assemblage at the sediment/water interface and ultimately on location of foramol versus chlorozoan production. Deep water transported onto and over the shelf may also have environmental ramifications beyond temperature by bringing in water of different chemistry.

  3. RTK/ERK Pathway under Natural Selection Associated with Prostate Cancer

    PubMed Central

    Xu, Jianfeng; Yu, Xiaoxiang; Li, Tianyu; Mo, Zengnan; Hu, Yanling

    2013-01-01

    Prostate cancer (PCa) is a global disease causing large numbers of deaths every year. Recent studies have indicated the RTK/ERK pathway might be a key pathway in the development of PCa. However, the exact association and evolution-based mechanism remain unclear. This study was conducted by combining genotypic and phenotypic data from the Chinese Consortium for Prostate Cancer Genetics (ChinaPCa) with related databases such as the HapMap Project and Genevar. In this analysis, expression of quantitative trait loci (eQTLs) analysis, natural selection and gene-based pathway analysis were involved. The pathway analysis confirmed the positive relationship between PCa risk and several key genes. In addition, combined with the natural selection, it seems that 4 genes (EGFR, ERBB2, PTK2, and RAF1) with five SNPs (rs11238349, rs17172438, rs984654, rs11773818, and rs17172432) especially rs17172432, might be pivotal factors in the development of PCa. The results indicate that the RTK/ERK pathway under natural selection is a key link in PCa risk. The joint effect of the genes and loci with positive selection might be one reason for the development of PCa. Dealing with all the factors simultaneously might give insight into prevention and aid in predicting the success of potential therapies for PCa. PMID:24223781

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

    PubMed Central

    2013-01-01

    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

  5. LABORATORY PROCESS CONTROLLER USING NATURAL LANGUAGE COMMANDS FROM A PERSONAL COMPUTER

    NASA Technical Reports Server (NTRS)

    Will, H.

    1994-01-01

    The complex environment of the typical research laboratory requires flexible process control. This program provides natural language process control from an IBM PC or compatible machine. Sometimes process control schedules require changes frequently, even several times per day. These changes may include adding, deleting, and rearranging steps in a process. This program sets up a process control system that can either run without an operator, or be run by workers with limited programming skills. The software system includes three programs. Two of the programs, written in FORTRAN77, record data and control research processes. The third program, written in Pascal, generates the FORTRAN subroutines used by the other two programs to identify the user commands with the user-written device drivers. The software system also includes an input data set which allows the user to define the user commands which are to be executed by the computer. To set the system up the operator writes device driver routines for all of the controlled devices. Once set up, this system requires only an input file containing natural language command lines which tell the system what to do and when to do it. The operator can make up custom commands for operating and taking data from external research equipment at any time of the day or night without the operator in attendance. This process control system requires a personal computer operating under MS-DOS with suitable hardware interfaces to all controlled devices. The program requires a FORTRAN77 compiler and user-written device drivers. This program was developed in 1989 and has a memory requirement of about 62 Kbytes.

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

    PubMed Central

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

    2008-01-01

    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

  7. Evidence for evolution in response to natural selection in a contemporary human population

    PubMed Central

    Milot, Emmanuel; Mayer, Francine M.; Nussey, Daniel H.; Boisvert, Mireille; Pelletier, Fanie; Réale, Denis

    2011-01-01

    It is often claimed that modern humans have stopped evolving because cultural and technological advancements have annihilated natural selection. In contrast, recent studies show that selection can be strong in contemporary populations. However, detecting a response to selection is particularly challenging; previous evidence from wild animals has been criticized for both applying anticonservative statistical tests and failing to consider random genetic drift. Here we study life-history variation in an insular preindustrial French-Canadian population and apply a recently proposed conservative approach to testing microevolutionary responses to selection. As reported for other such societies, natural selection favored an earlier age at first reproduction (AFR) among women. AFR was also highly heritable and genetically correlated to fitness, predicting a microevolutionary change toward earlier reproduction. In agreement with this prediction, AFR declined from about 26–22 y over a 140-y period. Crucially, we uncovered a substantial change in the breeding values for this trait, indicating that the change in AFR largely occurred at the genetic level. Moreover, the genetic trend was higher than expected under the effect of random genetic drift alone. Our results show that microevolution can be detectable over relatively few generations in humans and underscore the need for studies of human demography and reproductive ecology to consider the role of evolutionary processes. PMID:21969551

  8. The importance of selection at the level of the pair over 25 years in a natural population of birds

    PubMed Central

    Björklund, Mats; Gustafsson, Lars

    2013-01-01

    Knowledge of the pattern of selection in natural populations is fundamental for our understanding of the evolutionary process. Selection at higher levels has gained considerable theoretical support in recent years, and one possible level of selection is the breeding pair where fitness is a function of the pair and cannot be reduced to single individuals. We analyzed the importance of pair-level selection over 25 years in a natural population of the collared flycatcher. Pair-level selection was significant in five and probably in another 9 years. The relative importance of pair-level selection varied over years and can have stronger or the same strength as directional selection. This means that selection can act on the combination of the breeding pair in addition to selection on each individual separately. Overall, the conservative estimates obtained here show that this is a potentially important form of selection. PMID:24340199

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

    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.

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

    SciTech Connect

    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

    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.

  11. Materials from the Cell Factory Nature is a laboratory for particularly intelligent materials.This is what motivates Joachim Spatz,

    E-print Network

    . Such materials may be capable of regenera- tion. Today, research into these kinds of self-healing materialsMaterials from the Cell Factory Nature is a laboratory for particularly intelligent materials materials. Along the way, he anticipates new discoveries about the behavior of cells in tissues. TEXT ROLAND

  12. Inhibition of thrombin activity by selected natural products in comparison to neutrophil elastase.

    PubMed

    Melzig, Matthias F; Henke, Kristin

    2005-08-01

    Enzymatic thrombin activity is significantly inhibited only by a few selected natural phenolic compounds (myricetin, rosmarinic acid, caffeic acid phenethyl ester) but more strongly by unsaturated fatty acids like erucic acid and oleic acids. Compared to the inhibitory potential against neutrophil elastase, thrombin activity is rather weakly inhibited by phenolic compounds and fatty acids. Because of the importance of thrombin as a ligand for protease-activated receptor 1 (PAR-1), which is involved in inflammation, the inhibition of thrombin activity by natural compounds might enhance the anti-inflammatory effects of neutrophil elastase inhibition. PMID:16142650

  13. Laboratory studies of groundwater degassing in replicas of natural fractured rock for linear flow geometry

    SciTech Connect

    Geller, J.T.

    1998-02-01

    Laboratory experiments to simulate two-phase (gas and water) flow in fractured rock evolving from groundwater degassing were conducted in transparent replicas of natural rock fractures. These experiments extend the work by Geller et al. (1995) and Jarsjo and Geller (1996) that tests the hypothesis that groundwater degassing caused observed flow reductions in the Stripa Simulated Drift Experiment (SDE). Understanding degassing effects over a range of gas contents is needed due to the uncertainty in the gas contents of the water at the SDE. The main objectives of this study were to: (1) measure the effect of groundwater degassing on liquid flow rates for lower gas contents than the values used in Geller for linear flow geometry in the same fracture replicas of Geller; (2) provide a data set to develop a predictive model of two-phase flow in fractures for conditions of groundwater degassing; and (3) improve the certainty of experimental gas contents (this effort included modifications to the experimental system used by Geller et al. and separate gas-water equilibration tests). The Stripa site is being considered for a high-level radioactive waste repository.

  14. The Role of Selection in Shaping Diversity of Natural M. tuberculosis Populations

    PubMed Central

    Pepperell, Caitlin S.; Casto, Amanda M.; Kitchen, Andrew; Granka, Julie M.; Cornejo, Omar E.; Holmes, Eddie C.; Birren, Bruce; Galagan, James; Feldman, Marcus W.

    2013-01-01

    Mycobacterium tuberculosis (M.tb), the cause of tuberculosis (TB), is estimated to infect a new host every second. While analyses of genetic data from natural populations of M.tb have emphasized the role of genetic drift in shaping patterns of diversity, the influence of natural selection on this successful pathogen is less well understood. We investigated the effects of natural selection on patterns of diversity in 63 globally extant genomes of M.tb and related pathogenic mycobacteria. We found evidence of strong purifying selection, with an estimated genome-wide selection coefficient equal to ?9.5×10?4 (95% CI ?1.1×10?3 to ?6.8×10?4); this is several orders of magnitude higher than recent estimates for eukaryotic and prokaryotic organisms. We also identified different patterns of variation across categories of gene function. Genes involved in transport and metabolism of inorganic ions exhibited very low levels of non-synonymous polymorphism, equivalent to categories under strong purifying selection (essential and translation-associated genes). The highest levels of non-synonymous variation were seen in a group of transporter genes, likely due to either diversifying selection or local selective sweeps. In addition to selection, we identified other important influences on M.tb genetic diversity, such as a 25-fold expansion of global M.tb populations coincident with explosive growth in human populations (estimated timing 1684 C.E., 95% CI 1620–1713 C.E.). These results emphasize the parallel demographic histories of this obligate pathogen and its human host, and suggest that the dominant effect of selection on M.tb is removal of novel variants, with exceptions in an interesting group of genes involved in transportation and defense. We speculate that the hostile environment within a host imposes strict demands on M.tb physiology, and thus a substantial fitness cost for most new mutations. In this respect, obligate bacterial pathogens may differ from other host-associated microbes such as symbionts. PMID:23966858

  15. Variation in mycorrhizal performance in the epiphytic orchid Tolumnia variegata in vitro : the potential for natural selection

    Microsoft Academic Search

    J. Tupac Otero; Paul Bayman; James D. Ackerman

    2005-01-01

    Symbiotic seed germination is a critical stage in orchid life histories. Natural selection may act to favor plants that efficiently use mycorrhizal fungi. However, the necessary conditions for natural selection – variation, heritability, and differences in fitness – have not been demonstrated for either orchid or fungus. With the epiphytic orchid Tolumnia variegata as a model system, we ask the

  16. Measuring Knowledge of Natural Selection: A Comparison of the CINS, an Open-Response Instrument, and an Oral Interview

    ERIC Educational Resources Information Center

    Nehm, Ross H.; Schonfeld, Irvin Sam

    2008-01-01

    Growing recognition of the central importance of fostering an in-depth understanding of natural selection has, surprisingly, failed to stimulate work on the development and rigorous evaluation of instruments that measure knowledge of it. We used three different methodological tools, the Conceptual Inventory of Natural Selection (CINS), a modified…

  17. I'm Looking Over a White-Striped Clover A Natural Selection Case

    NSDL National Science Digital Library

    Susan Evarts

    2006-01-01

    This case is an exploration of the process of natural selection using white clover (Trifolium repens) as an example. In general, two forms of white clover can be found around the world in various habitats. One type is able to produce cyanide in its leaves, while the other is not. This variation within the clover species, along with the fact that cyanide production is paired with the production of a white stripe on the leaf, is used to teach the process of evolution through natural selection. Students use the scientific method to explore these concepts. As an introduction to evolutionary concepts in biology, the case would be appropriate for both high school and college biology courses.

  18. A signal integration model of thymic selection and natural regulatory T cell commitment.

    PubMed

    Khailaie, Sahamoddin; Robert, Philippe A; Toker, Aras; Huehn, Jochen; Meyer-Hermann, Michael

    2014-12-15

    The extent of TCR self-reactivity is the basis for selection of a functional and self-tolerant T cell repertoire and is quantified by repeated engagement of TCRs with a diverse pool of self-peptides complexed with self-MHC molecules. The strength of a TCR signal depends on the binding properties of a TCR to the peptide and the MHC, but it is not clear how the specificity to both components drives fate decisions. In this study, we propose a TCR signal-integration model of thymic selection that describes how thymocytes decide among distinct fates, not only based on a single TCR-ligand interaction, but taking into account the TCR stimulation history. These fates are separated based on sustained accumulated signals for positive selection and transient peak signals for negative selection. This spans up the cells into a two-dimensional space where they are either neglected, positively selected, negatively selected, or selected as natural regulatory T cells (nTregs). We show that the dynamics of the integrated signal can serve as a successful basis for extracting specificity of thymocytes to MHC and detecting the existence of cognate self-peptide-MHC. It allows to select a self-MHC-biased and self-peptide-tolerant T cell repertoire. Furthermore, nTregs in the model are enriched with MHC-specific TCRs. This allows nTregs to be more sensitive to activation and more cross-reactive than conventional T cells. This study provides a mechanistic model showing that time integration of TCR-mediated signals, as opposed to single-cell interaction events, is needed to gain a full view on the properties emerging from thymic selection. PMID:25392533

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

    Microsoft Academic Search

    Ross H. Nehm; Hendrik Haertig

    2011-01-01

    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.

  20. Phenology of Agromyzid (Diptera) leafminers and their natural enemies on selected Texas native plants

    E-print Network

    Praetorius, Richard Leonhardt

    1990-01-01

    as to style and content by: Robert Wharton (Chair of Committee) ugh Wilson (Member) p)/i' Joseph Sch' ffner (Membe ) , it Fowden axwell (Head of Department) December 1990 ABSTRACT Phenology of Agromyzid (Diptera) Leafminers and Their Natural... Enemies on Selected Texas Native Plants. (December 1990) Richard Leonhardt Praetorius, B. S. , Central Missouri State University; Chair of Advisory Committee: Dr. Robert Wharton The two annual bluebonnet species, Lupinus texensis and L. subcarnosus...

  1. On the moulding of senescence by natural selection in sexual and partly sexual populations

    Microsoft Academic Search

    Ilan Eshel; Beverly Sackler

    1990-01-01

    Under a wide variety of dynamic environmental conditions, natural selection appears to favor reproductive investment in a\\u000a sexually produced offspring, carrying only half of the mother’s genes, over the investment in an asexually produced offspring,\\u000a genetically identical to her. It is maintained that the same environmental conditions must affect the evolutionary cost and\\u000a benefit of an investment in the prolongation

  2. Natural Image Coding in V1: How Much Use is Orientation Selectivity?

    Microsoft Academic Search

    Jan Eichhorn; Fabian Sinz; Matthias Bethge

    2008-01-01

    Orientation selectivity is the most striking feature of simple cell coding in V1 which 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

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

    Microsoft Academic Search

    Ross Cressman; József Garay; Zoltán Varga

    2003-01-01

    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

  4. Darwin's passionate environmentalism or the dangerous fallacy of the 'All-sufficiency of natural selection' theory.

    PubMed

    Marsh, David

    2012-01-01

    Following his last edition of the Origin of Species in 1872, Darwin spent much of the rest of his life searching for possible mechanisms, such as the pangenes in the blood, which would communicate information from the environment to the genome. In each of his six editions of the 'Origin', he stated that there were two forces in evolution - natural selection and conditions of existence. Of the two, he claims that the latter is the more powerful. In so doing, he recognized that natural selection could only operate within the bounds of possibility, that is the environment. August Weismann claimed that conditions of existence had no place in evolution. His publication, the 'All-sufficiency of natural selection', was based on mutilation (cutting tails of rodents and watching the next generation grow tails), which has nothing to do with Darwin's concept of conditions of existence. Nonetheless, evolutionary biologists in general followed the line of the 'all sufficiency' theory and ignored Darwin's conditions of existence, which in other words means the environment. Natural selection has a weak predictive power as it is based on random events. However, the conditions of existence have, by contrast, strong predictive powers that can be tested. The environmental views of two of the greatest evolutionists, Lamarck and Darwin, have been consistently ignored by most evolution theorists who came after them, continuing for over 200 years. Looking at the fossil record through the eyes of Darwin's conditions of existence, not to mention the recent changes in height and shape over the last century, it is possible to draw important conclusions about the past and predictions of the future. With new knowledge of epigenetics, it is perhaps time that Darwin's conditions of existence were given a second hearing. PMID:22544777

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

    PubMed Central

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

    2011-01-01

    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

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

    PubMed

    Lau, Jennifer A

    2008-04-01

    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

  7. Form and nature of precopulatory sexual selection in both sexes of a moth

    NASA Astrophysics Data System (ADS)

    Xu, Jin; Wang, Qiao

    2010-07-01

    Sexual selection is a process that operates through intrasexual competition and intersexual choice for reproduction in both sexes. Here, we report our work on a polygamous moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), aiming to infer the form and nature of precopulatory sexual selection in males and females. We show that, although a number of traits measured in each sex are correlated with mating success, the primary selection trait in females appears to be abdominal thickness and that in males is aedeagus length. As the female’s abdominal thickness is a reliable signal about the number and developmental stage of eggs, males who select females with thicker abdomens for mating will gain reproductive benefit, i.e., fertilizing more mature eggs. For females, earlier maturation of their eggs makes the females more likely to achieve mating earlier in an uncertain world where there is no guarantee that they will find more males in the future. Sexual selection appears to be the important force behind the evolution of fast egg maturation in females. We show that, under a male-biased sex ratio, more than 20% of mating fails within a few minutes after the aedeagus has penetrated into the female’s genitalia, suggesting that females can assess the features of the male aedeagus before allowing insemination to occur. Dissection and examination of both sexes suggest that a longer aedeagus enhances mating and fertilization efficiency in this species, supporting the notion that sexual selection is a primary force in the evolution of genital variance.

  8. Implications of quantum metabolism and natural selection for the origin of cancer cells and tumor progression

    NASA Astrophysics Data System (ADS)

    Davies, Paul; Demetrius, Lloyd A.; Tuszynski, Jack A.

    2012-03-01

    Empirical studies give increased support for the hypothesis that the sporadic form of cancer is an age-related metabolic disease characterized by: (a) metabolic dysregulation with random abnormalities in mitochondrial DNA, and (b) metabolic alteration - the compensatory upregulation of glycolysis to offset mitochondrial impairments. This paper appeals to the theory of Quantum Metabolism and the principles of natural selection to formulate a conceptual framework for a quantitative analysis of the origin and proliferation of the disease. Quantum Metabolism, an analytical theory of energy transduction in cells inspired by the methodology of the quantum theory of solids, elucidates the molecular basis for differences in metabolic rate between normal cells, utilizing predominantly oxidative phosphorylation, and cancer cells utilizing predominantly glycolysis. The principles of natural selection account for the outcome of competition between the two classes of cells. Quantum Metabolism and the principles of natural selection give an ontogenic and evolutionary rationale for cancer proliferation and furnish a framework for effective therapeutic strategies to impede the spread of the disease.

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

    PubMed Central

    2013-01-01

    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

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

    PubMed Central

    Leigh, Egbert Giles; Vermeij, Geerat Jacobus

    2002-01-01

    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

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

    PubMed

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

    2014-12-01

    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

  12. Selective MyD88-dependent pathway inhibition by the cyanobacterial natural product malyngamide F acetate

    PubMed Central

    Villa, Francisco A.; Lieske, Kelly; Gerwick, Lena

    2010-01-01

    In response to evolutionary selective pressure, prokaryotes have developed a rich array of secondary metabolites, some of which may be inhibitory to the innate immune system and the inflammatory response in vertebrates. We utilized the RAW264.7 macrophage cell line stimulated with LPS in a nitric oxide (NO) assay to screen for compounds with immunomodulatory activities from a library of marine natural products, and found that the malyngamide structure class, found commonly in the marine cyanobacterium Lyngbya majuscula, has potent activity. Several of the malyngamides were found to possess IC50 values of 5.4 – 18 ?M. Malyngamide F acetate exhibited strong concentration-dependent anti-inflammatory activity in the NO assay with an IC50 of 7.1 ?M and with no cytotoxicity at the concentrations tested. Subsequent real-time PCR of selected genes revealed a unique cytokine profile after LPS stimulation (TLR4) with decreased expression of iNOS, IL-1?, IL-6, and IL-10, but increased TNF-? expression. Additional experiments utilizing CpG and Poly I:C stimulation to selectively activate the MyD88-dependent and -independent pathways via TLR9 and TLR3 substantiated the finding that malyngamide F acetate selectively inhibits the MyD88-dependent pathway. To our knowledge, this is the first report of a natural product inhibiting the MyD88-dependent pathway. PMID:20006962

  13. Targeted activation of silent natural product biosynthesis pathways by reporter-guided mutant selection.

    PubMed

    Guo, Fang; Xiang, Sihai; Li, Liyuan; Wang, Bin; Rajasärkkä, Johanna; Gröndahl-Yli-Hannuksela, Kirsi; Ai, Guomin; Metsä-Ketelä, Mikko; Yang, Keqian

    2015-03-01

    The continuously increasing genome sequencing data has revealed numerous cryptic pathways, which might encode novel secondary metabolites with interesting biological activities. However, utilization of this hidden potential has been hindered by the observation that many of these gene clusters remain silent (or poorly expressed) under laboratory conditions. Here we present reporter-guided mutant selection (RGMS) as an effective and widely applicable method for targeted activation of silent gene clusters in the native producers. The strategy takes advantage of genome-scale random mutagenesis for generation of genetic diversity and a reporter-guided selection system for the identification of the desired target-activated mutants. It was first validated in the re-activation of jadomycin biosynthesis in Streptomyces venezuelae ISP5230, where high efficiency of activation was achieved. The same strategy was then applied to a hitherto unactivable pga gene cluster in Streptomyces sp. PGA64 leading to the identification of two new anthraquinone aminoglycosides, gaudimycin D and E. PMID:25554073

  14. Selecting the Best Mobile Information Service with Natural Language User Input

    NASA Astrophysics Data System (ADS)

    Feng, Qiangze; Qi, Hongwei; Fukushima, Toshikazu

    Information services accessed via mobile phones provide information directly relevant to subscribers’ daily lives and are an area of dynamic market growth worldwide. Although many information services are currently offered by mobile operators, many of the existing solutions require a unique gateway for each service, and it is inconvenient for users to have to remember a large number of such gateways. Furthermore, the Short Message Service (SMS) is very popular in China and Chinese users would prefer to access these services in natural language via SMS. This chapter describes a Natural Language Based Service Selection System (NL3S) for use with a large number of mobile information services. The system can accept user queries in natural language and navigate it to the required service. Since it is difficult for existing methods to achieve high accuracy and high coverage and anticipate which other services a user might want to query, the NL3S is developed based on a Multi-service Ontology (MO) and Multi-service Query Language (MQL). The MO and MQL provide semantic and linguistic knowledge, respectively, to facilitate service selection for a user query and to provide adaptive service recommendations. Experiments show that the NL3S can achieve 75-95% accuracies and 85-95% satisfactions for processing various styles of natural language queries. A trial involving navigation of 30 different mobile services shows that the NL3S can provide a viable commercial solution for mobile operators.

  15. Identifying signatures of natural selection in Tibetan and Andean populations using dense genome scan data.

    PubMed

    Bigham, Abigail; Bauchet, Marc; Pinto, Dalila; Mao, Xianyun; Akey, Joshua M; Mei, Rui; Scherer, Stephen W; Julian, Colleen G; Wilson, Megan J; López Herráez, David; Brutsaert, Tom; Parra, Esteban J; Moore, Lorna G; Shriver, Mark D

    2010-09-01

    High-altitude hypoxia (reduced inspired oxygen tension due to decreased barometric pressure) exerts severe physiological stress on the human body. Two high-altitude regions where humans have lived for millennia are the Andean Altiplano and the Tibetan Plateau. Populations living in these regions exhibit unique circulatory, respiratory, and hematological adaptations to life at high altitude. Although these responses have been well characterized physiologically, their underlying genetic basis remains unknown. We performed a genome scan to identify genes showing evidence of adaptation to hypoxia. We looked across each chromosome to identify genomic regions with previously unknown function with respect to altitude phenotypes. In addition, groups of genes functioning in oxygen metabolism and sensing were examined to test the hypothesis that particular pathways have been involved in genetic adaptation to altitude. Applying four population genetic statistics commonly used for detecting signatures of natural selection, we identified selection-nominated candidate genes and gene regions in these two populations (Andeans and Tibetans) separately. The Tibetan and Andean patterns of genetic adaptation are largely distinct from one another, with both populations showing evidence of positive natural selection in different genes or gene regions. Interestingly, one gene previously known to be important in cellular oxygen sensing, EGLN1 (also known as PHD2), shows evidence of positive selection in both Tibetans and Andeans. However, the pattern of variation for this gene differs between the two populations. Our results indicate that several key HIF-regulatory and targeted genes are responsible for adaptation to high altitude in Andeans and Tibetans, and several different chromosomal regions are implicated in the putative response to selection. These data suggest a genetic role in high-altitude adaption and provide a basis for future genotype/phenotype association studies necessary to confirm the role of selection-nominated candidate genes and gene regions in adaptation to altitude. PMID:20838600

  16. Laboratory evaluation of selected shale oil asphalts in paving mixtures. Report RF-3403-1

    SciTech Connect

    Button, J.W.; Epps, J.A.; Gallaway, B.M.

    1978-01-01

    Shale oil asphalt cements originating from the Green River formation in Colorado were characterized by laboratory tests commonly used in specifying paving asphalts. The asphalt cements were mixed with two common aggregates to fabricate laboratory specimens which were tested to identify paving mixture characteristics such as compactibility, stability, stiffness, tensile strength, and water susceptibility. Test results were compared to similar characteristics of a petroleum asphalt cement and petroleum asphalt-aggregate mixtures. Laboratory test results indicate no fundamental differences between shale oil asphalt and petroleum asphalt and furthermore properties of the mixtures are shown to be satisfactory when compared to standard specifications. 27 figures, 12 tables.

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

    E-print Network

    Theodorakis, Emmanuel

    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

  18. 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...

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

    PubMed

    Byers, John; Dunn, Stacey

    2012-11-01

    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

  20. Natural Selection in a Bangladeshi Population from the Cholera-Endemic Ganges River Delta

    PubMed Central

    Karlsson, Elinor K.; Harris, Jason B.; Tabrizi, Shervin; Rahman, Atiqur; Shlyakhter, Ilya; Patterson, Nick; O'Dushlaine, Colm; Schaffner, Stephen F.; Gupta, Sameer; Chowdhury, Fahima; Sheikh, Alaullah; Shin, Ok Sarah; Ellis, Crystal; Becker, Christine E.; Stuart, Lynda M.; Calderwood, Stephen B.; Ryan, Edward T.; Qadri, Firdausi; Sabeti, Pardis C.; LaRocque, Regina C.

    2015-01-01

    As an ancient disease with high fatality, cholera has likely exerted strong selective pressure on affected human populations. We performed a genome-wide study of natural selection in a population from the Ganges River Delta, the historic geographic epicenter of cholera. We identified 305 candidate selected regions using the Composite of Multiple Signals (CMS) method. The regions were enriched for potassium channel genes involved in cyclic AMP-mediated chloride secretion and for components of the innate immune system involved in NF-?B signaling. We demonstrate that a number of these strongly selected genes are associated with cholera susceptibility in two separate cohorts. We further identify repeated examples of selection and association in an NF-kB / inflammasome-dependent pathway that is activated in vitro by Vibrio cholerae. Our findings shed light on the genetic basis of cholera resistance in a population from the Ganges River Delta and present a promising approach for identifying genetic factors influencing susceptibility to infectious diseases. PMID:23825302

  1. 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

    Touaibia, Mohamed; Guay, Michel

    2011-01-01

    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…

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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.

  3. Hands-On Laboratory Simulation of Evolution: An Investigation of Mutation, Natural Selection, & Speciation

    ERIC Educational Resources Information Center

    Hildebrand, Terri J.; Govedich, Fredric R.; Bain, Bonnie A.

    2010-01-01

    Evolutionary theory is the foundation of the biological sciences, yet conveying it to General Biology students often presents a challenge, especially at larger institutions where student numbers in foundation courses can exceed several hundred per lecture section. We present a pedagogically sound exercise that utilizes a series of simple and…

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

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

    ERIC Educational Resources Information Center

    Ericsson, K. Anders; Williams, A. Mark

    2007-01-01

    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…

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

    PubMed Central

    Wei, Xinzhu; Zhang, Jianzhi

    2015-01-01

    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

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

    PubMed

    Wei, Xinzhu; Zhang, Jianzhi

    2015-01-01

    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

  8. An experimental demonstration of Fisher's principle: evolution of sexual proportion by natural selection.

    PubMed Central

    Carvalho, A B; Sampaio, M C; Varandas, F R; Klaczko, L B

    1998-01-01

    Most sexually reproducing species have sexual proportions around 1:1. This major biological phenomenon remained unexplained until 1930, when FISHER proposed that it results from a mechanism of natural selection. Here we report the first experimental test of his model that obeys all its assumptions. We used a naturally occurring X-Y meiotic drive system--the sex-ratio trait of Drosophila mediopunctat--to generate female-biased experimental populations. As predicted by FISHER, these populations evolved toward equal sex proportions due to natural selection, by accumulation of autosomal alleles that direct the parental reproductive effort toward the rare sex. Classical Fisherian evolution is a rather slow mechanism: despite a very large amount of genetic variability, the experimental populations evolved from 16% of males to 32% of males in 49 generations and would take 330 generations (29 years) to reach 49%. This slowness has important implications for species potentially endangered by skewed sexual proportions, such as reptiles with temperature sex determination. PMID:9504919

  9. Evidence of natural selection acting on a polymorphic hybrid incompatibility locus in mimulus.

    PubMed

    Sweigart, Andrea L; Flagel, Lex E

    2015-02-01

    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 M. 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

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

    PubMed

    St Juliana, J R; Janzen, F J

    2007-07-01

    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

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

    ERIC Educational Resources Information Center

    Creager, Stephen E.; And Others

    1995-01-01

    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…

  12. INSECTICIDE RESISTANCE MECHANISMS AFTER LABORATORY SELECTION WITH CYPERMETHRIN IN THE GERMAN COCKROACH, BLATTELLA GERMANICA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A cross resistant strain of German cockroach (Marietta) expressing multiple resistance mechanisms was subjected to intense cypermethrin selection pressure. Resistance to cypermethrin increased incrementally from 3.6-fold in the parental strain to 35-fold after 4 rounds of selection. Piperonyl butox...

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

    PubMed Central

    2013-01-01

    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

  14. Laboratory methods for evaluating migrated high molecular weight hydrocarbons in marine sediments at naturally occurring oil seeps

    Microsoft Academic Search

    Graham A. Logan; Michael A. Abrams; Nicola F. Dahdah; Emmanuelle Grosjean

    2009-01-01

    A laboratory study has been conducted to determine the best methods for the detection of C10–C40 hydrocarbons at naturally occurring oil seeps in marine sediments. The results indicate that a commercially available method using n-C6 to extract sediments and gas chromatography–flame ionization detection (GC–FID) to screen the resulting extract is effective at recognizing the presence of migrated hydrocarbons at concentrations

  15. Culture and maintenance of selected invertebrates in the laboratory and classroom.

    PubMed

    Smith, Stephen A; Scimeca, Joseph M; Mainous, Mary E

    2011-01-01

    Invertebrate species have been used for many years in the laboratory and teaching environment. We discuss some of the most commonly maintained invertebrates--the nematode (Caenorhabditis elegans), the California sea hare (Aplysia californica), the fruit fly (Drosophila melanogaster), terrestrial hermit crabs, the horseshoe crab (Limulus polyphemus), and cephalopods--and briefly describe general techniques for culturing them in captivity. The aim of this article is to give potential users an idea of the materials, methods, and effort required to maintain each type of organism in a laboratory or classroom setting. PMID:21709308

  16. Implications of participant self-selection for generalizability: who participates in smoking laboratory research?

    PubMed

    Kamholz, Barbara W; Gulliver, Suzy Bird; Helstrom, Amy; Morissette, Sandra B

    2009-01-01

    The generalizability of data from laboratory smoking studies using volunteer samples is debatable. We tracked potential participants from first contact with research staff through screening to study completion. We found that a minority of individuals were ultimately enrolled in the study. Failure to enroll was as often a function of participant lack of attendance at the laboratory as a function of ineligibility. With some exceptions, groups of potential participants were similar regarding demographic characteristics and substance use history. These findings support the generalizability of the sample and highlight the importance of documenting details of study eligibility and participation. The study's limitations are noted. PMID:19212926

  17. Natural Selection on Individual Variation in Tolerance of Gastrointestinal Nematode Infection

    PubMed Central

    Hayward, Adam D.; Nussey, Daniel H.; Wilson, Alastair J.; Berenos, Camillo; Pilkington, Jill G.; Watt, Kathryn A.; Pemberton, Josephine M.; Graham, Andrea L.

    2014-01-01

    Hosts may mitigate the impact of parasites by two broad strategies: resistance, which limits parasite burden, and tolerance, which limits the fitness or health cost of increasing parasite burden. The degree and causes of variation in both resistance and tolerance are expected to influence host–parasite evolutionary and epidemiological dynamics and inform disease management, yet very little empirical work has addressed tolerance in wild vertebrates. Here, we applied random regression models to longitudinal data from an unmanaged population of Soay sheep to estimate individual tolerance, defined as the rate of decline in body weight with increasing burden of highly prevalent gastrointestinal nematode parasites. On average, individuals lost weight as parasite burden increased, but whereas some lost weight slowly as burden increased (exhibiting high tolerance), other individuals lost weight significantly more rapidly (exhibiting low tolerance). We then investigated associations between tolerance and fitness using selection gradients that accounted for selection on correlated traits, including body weight. We found evidence for positive phenotypic selection on tolerance: on average, individuals who lost weight more slowly with increasing parasite burden had higher lifetime breeding success. This variation did not have an additive genetic basis. These results reveal that selection on tolerance operates under natural conditions. They also support theoretical predictions for the erosion of additive genetic variance of traits under strong directional selection and fixation of genes conferring tolerance. Our findings provide the first evidence of selection on individual tolerance of infection in animals and suggest practical applications in animal and human disease management in the face of highly prevalent parasites. PMID:25072883

  18. Natural selection on individual variation in tolerance of gastrointestinal nematode infection.

    PubMed

    Hayward, Adam D; Nussey, Daniel H; Wilson, Alastair J; Berenos, Camillo; Pilkington, Jill G; Watt, Kathryn A; Pemberton, Josephine M; Graham, Andrea L

    2014-07-01

    Hosts may mitigate the impact of parasites by two broad strategies: resistance, which limits parasite burden, and tolerance, which limits the fitness or health cost of increasing parasite burden. The degree and causes of variation in both resistance and tolerance are expected to influence host-parasite evolutionary and epidemiological dynamics and inform disease management, yet very little empirical work has addressed tolerance in wild vertebrates. Here, we applied random regression models to longitudinal data from an unmanaged population of Soay sheep to estimate individual tolerance, defined as the rate of decline in body weight with increasing burden of highly prevalent gastrointestinal nematode parasites. On average, individuals lost weight as parasite burden increased, but whereas some lost weight slowly as burden increased (exhibiting high tolerance), other individuals lost weight significantly more rapidly (exhibiting low tolerance). We then investigated associations between tolerance and fitness using selection gradients that accounted for selection on correlated traits, including body weight. We found evidence for positive phenotypic selection on tolerance: on average, individuals who lost weight more slowly with increasing parasite burden had higher lifetime breeding success. This variation did not have an additive genetic basis. These results reveal that selection on tolerance operates under natural conditions. They also support theoretical predictions for the erosion of additive genetic variance of traits under strong directional selection and fixation of genes conferring tolerance. Our findings provide the first evidence of selection on individual tolerance of infection in animals and suggest practical applications in animal and human disease management in the face of highly prevalent parasites. PMID:25072883

  19. Genomic signatures of geographic isolation and natural selection in coral reef fishes.

    PubMed

    Gaither, Michelle R; Bernal, Moisés A; Coleman, Richard R; Bowen, Brian W; Jones, Shelley A; Simison, W Brian; Rocha, Luiz A

    2015-04-01

    The drivers of speciation remain among the most controversial topics in evolutionary biology. Initially, Darwin emphasized natural selection as a primary mechanism of speciation, but the architects of the modern synthesis largely abandoned that view in favour of divergence by geographic isolation. The balance between selection and isolation is still at the forefront of the evolutionary debate, especially for the world's tropical oceans where biodiversity is high, but isolating barriers are few. Here, we identify the drivers of speciation in Pacific reef fishes of the genus Acanthurus by comparative genome scans of two peripheral populations that split from a large Central-West Pacific lineage at roughly the same time. Mitochondrial sequences indicate that populations in the Hawaiian Archipelago and the Marquesas Islands became isolated approximately 0.5 Ma. The Hawaiian lineage is morphologically indistinguishable from the widespread Pacific form, but the Marquesan form is recognized as a distinct species that occupies an unusual tropical ecosystem characterized by upwelling, turbidity, temperature fluctuations, algal blooms and little coral cover. An analysis of 3737 SNPs reveals a strong signal of selection at the Marquesas, with 59 loci under disruptive selection including an opsin Rh2 locus. While both the Hawaiian and Marquesan populations indicate signals of drift, the former shows a weak signal of selection that is comparable with populations in the Central-West Pacific. This contrast between closely related lineages reveals one population diverging due primarily to geographic isolation and genetic drift, and the other achieving taxonomic species status under the influence of selection. PMID:25753379

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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.

  1. Epigenetics as an answer to Darwin's "special difficulty," Part 2: natural selection of metastable epialleles in honeybee castes.

    PubMed

    Ruden, Douglas M; Cingolani, Pablo E; Sen, Arko; Qu, Wen; Wang, Luan; Senut, Marie-Claude; Garfinkel, Mark D; Sollars, Vincent E; Lu, Xiangyi

    2015-01-01

    In a recent perspective in this journal, Herb (2014) discussed how epigenetics is a possible mechanism to circumvent Charles Darwin's "special difficulty" in using natural selection to explain the existence of the sterile-fertile dimorphism in eusocial insects. Darwin's classic book "On the Origin of Species by Means of Natural Selection" explains how natural selection of the fittest individuals in a population can allow a species to adapt to a novel or changing environment. However, in bees and other eusocial insects, such as ants and termites, there exist two or more castes of genetically similar females, from fertile queens to multiple sub-castes of sterile workers, with vastly different phenotypes, lifespans, and behaviors. This necessitates the selection of groups (or kin) rather than individuals in the evolution of honeybee hives, but group and kin selection theories of evolution are controversial and mechanistically uncertain. Also, group selection would seem to be prohibitively inefficient because the effective population size of a colony is reduced from thousands to a single breeding queen. In this follow-up perspective, we elaborate on possible mechanisms for how a combination of both epigenetics, specifically, the selection of metastable epialleles, and genetics, the selection of mutations generated by the selected metastable epialleles, allows for a combined means for selection amongst the fertile members of a species to increase colony fitness. This "intra-caste evolution" hypothesis is a variation of the epigenetic directed genetic error hypothesis, which proposes that selected metastable epialleles increase genetic variability by directing mutations specifically to the epialleles. Natural selection of random metastable epialleles followed by a second round of natural selection of random mutations generated by the metastable epialleles would allow a way around the small effective population size of eusocial insects. PMID:25759717

  2. Epigenetics as an answer to Darwin’s “special difficulty,” Part 2: natural selection of metastable epialleles in honeybee castes

    PubMed Central

    Ruden, Douglas M.; Cingolani, Pablo E.; Sen, Arko; Qu, Wen; Wang, Luan; Senut, Marie-Claude; Garfinkel, Mark D.; Sollars, Vincent E.; Lu, Xiangyi

    2015-01-01

    In a recent perspective in this journal, Herb (2014) discussed how epigenetics is a possible mechanism to circumvent Charles Darwin’s “special difficulty” in using natural selection to explain the existence of the sterile-fertile dimorphism in eusocial insects. Darwin’s classic book “On the Origin of Species by Means of Natural Selection” explains how natural selection of the fittest individuals in a population can allow a species to adapt to a novel or changing environment. However, in bees and other eusocial insects, such as ants and termites, there exist two or more castes of genetically similar females, from fertile queens to multiple sub-castes of sterile workers, with vastly different phenotypes, lifespans, and behaviors. This necessitates the selection of groups (or kin) rather than individuals in the evolution of honeybee hives, but group and kin selection theories of evolution are controversial and mechanistically uncertain. Also, group selection would seem to be prohibitively inefficient because the effective population size of a colony is reduced from thousands to a single breeding queen. In this follow-up perspective, we elaborate on possible mechanisms for how a combination of both epigenetics, specifically, the selection of metastable epialleles, and genetics, the selection of mutations generated by the selected metastable epialleles, allows for a combined means for selection amongst the fertile members of a species to increase colony fitness. This “intra-caste evolution” hypothesis is a variation of the epigenetic directed genetic error hypothesis, which proposes that selected metastable epialleles increase genetic variability by directing mutations specifically to the epialleles. Natural selection of random metastable epialleles followed by a second round of natural selection of random mutations generated by the metastable epialleles would allow a way around the small effective population size of eusocial insects. PMID:25759717

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

    PubMed Central

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

    2004-01-01

    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

  4. Incipient Balancing Selection through Adaptive Loss of Aquaporins in Natural Saccharomyces cerevisiae Populations

    PubMed Central

    Will, Jessica L.; Kim, Hyun Seok; Clarke, Jessica; Painter, John C.; Fay, Justin C.; Gasch, Audrey P.

    2010-01-01

    A major goal in evolutionary biology is to understand how adaptive evolution has influenced natural variation, but identifying loci subject to positive selection has been a challenge. Here we present the adaptive loss of a pair of paralogous genes in specific Saccharomyces cerevisiae subpopulations. We mapped natural variation in freeze-thaw tolerance to two water transporters, AQY1 and AQY2, previously implicated in freeze-thaw survival. However, whereas freeze-thaw–tolerant strains harbor functional aquaporin genes, the set of sensitive strains lost aquaporin function at least 6 independent times. Several genomic signatures at AQY1 and/or AQY2 reveal low variation surrounding these loci within strains of the same haplotype, but high variation between strain groups. This is consistent with recent adaptive loss of aquaporins in subgroups of strains, leading to incipient balancing selection. We show that, although aquaporins are critical for surviving freeze-thaw stress, loss of both genes provides a major fitness advantage on high-sugar substrates common to many strains' natural niche. Strikingly, strains with non-functional alleles have also lost the ancestral requirement for aquaporins during spore formation. Thus, the antagonistic effect of aquaporin function—providing an advantage in freeze-thaw tolerance but a fitness defect for growth in high-sugar environments—contributes to the maintenance of both functional and nonfunctional alleles in S. cerevisiae. This work also shows that gene loss through multiple missense and nonsense mutations, hallmarks of pseudogenization presumed to emerge after loss of constraint, can arise through positive selection. PMID:20369021

  5. Goal-Side Selection in Soccer Penalty Kicking When Viewing Natural Scenes

    PubMed Central

    Weigelt, Matthias; Memmert, Daniel

    2012-01-01

    The present study investigates the influence of goalkeeper displacement on goal-side selection in soccer penalty kicking. Facing a penalty situation, participants viewed photo-realistic images of a goalkeeper and a soccer goal. In the action selection task, they were asked to kick to the greater goal-side, and in the perception task, they indicated the position of the goalkeeper on the goal line. To this end, the goalkeeper was depicted in a regular goalkeeping posture, standing either in the exact middle of the goal or being displaced at different distances to the left or right of the goal’s center. Results showed that the goalkeeper’s position on the goal line systematically affected goal-side selection, even when participants were not aware of the displacement. These findings provide further support for the notion that the implicit processing of the stimulus layout in natural scenes can effect action selection in complex environments, such in soccer penalty shooting. PMID:22973246

  6. Seasonal and diel habitat selection by bluegills in a shallow natural lake

    USGS Publications Warehouse

    Paukert, C.P.; Willis, D.W.

    2002-01-01

    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 (200 mm total length [TL]) bluegills in a shallow (mean depth = 1.2 m), 332-ha, natural lake (Pelican Lake, Nebraska) with both emergent and submergent vegetation distributed throughout. A total of 78 bluegills (200-273 mm TL) were implanted with radio transmitters and relocated daily for 6 d per month (April-September); up to 20 of the tagged fish were relocated every 2 h for a 24-h period once each month. Regardless of diel period, bluegills used open-water, emergent vegetation, submergent vegetation, and mixed emergent - submergent vegetation habitat types in similar proportions. During April, June, and July, male bluegills positively selected emergent vegetation, whereas female bluegills showed no vegetation selection preference during any month. Throughout the study period, bluegills never avoided open-water habitats, suggesting that larger individuals may continue to use open-water habitats in proportion to their availability. In addition, emergent vegetation appeared to be important, particularly for male bluegills. Although the mechanism for the positive selection of emergent vegetation by males was unclear, the protection or enhancement of such habitats may facilitate the preservation of quality bluegill populations in shallow lakes.

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

    PubMed

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

    2014-01-01

    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

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

    PubMed

    Smith, Charles H

    2014-11-26

    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

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

    USGS Publications Warehouse

    Erdmann, D.E.

    1975-01-01

    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.

  10. Taming of a superbase for selective phenol desilylation and natural product isolation.

    PubMed

    Trader, Darci J; Carlson, Erin E

    2013-07-19

    Hydroxyl moieties are highly prevalent in natural products. We previously reported a chemoselective strategy for enrichment of hydroxyl-functionalized molecules by formation of a silyl ether bond to a resin. To generate smaller pools of molecules for analysis, we developed cleavage conditions to promote stepwise release of phenolic silyl ethers followed by aliphatic silyl ethers with a "tamed" version of the superbase 1,1,3,3-tetramethylguanadine. We demonstrate this as a general strategy for selective deprotection of phenolic silyl ethers under neutral conditions at room temperature. PMID:23815363

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

    PubMed

    Sullivan-Clarke, Andrea

    2013-12-01

    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

  12. [Selection of a mixed culture of cellulosolytic thermophilic anaerobes from various natural sources].

    PubMed

    Ziabreva, N V; Isakova, E P; Biriukov, V V

    2001-01-01

    Microbial associations capable of converting cellulose-containing substrates to ethanol and organic acids were isolated from natural sources. The resulting mixed cultures utilized cellulose, cellobiose, glucose, maize residue, cotton, and flax boon producing ethanol (up to 0.9 g/l) and acetic acid (up to 0.8 g/l). The most complete conversion of cellulose-containing substrates occurred at 60 degrees C, pH 7.0. The selected association of thermophilic anaerobic bacteria produced 0.64 g ethanol per g substrate utilized at the ethanol/acetate ratio 4.7:1. PMID:11530665

  13. 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

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

    2005-01-01

    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.

  14. Assessment Laboratory Model. Fire Fighter Selection Examination Developed for City of Palo Alto, California.

    ERIC Educational Resources Information Center

    Harris, J. David; Macrae, Donald S.

    The assessment laboratory function is supplementary and subsequent to the usual mass testing procedures. It is designed to elicit information not furnished by older more traditional methods, e.g., assessment of personal attributes, communication skills, etc. The exam involved participation by the candidates in both individual and group exercises.…

  15. 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 ...

  16. 75 FR 53277 - Notice of Intent To Terminate Selected National Voluntary Laboratory Accreditation Program (NVLAP...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-31

    ...includes the following areas of testing: paints and related coatings, paper and related...includes the following areas of testing: paints and related coatings, paper and related...laboratories are also accredited for plastic and paint testing in support of plumbing...

  17. Site selection by Microphallus pygmaeus Levinsen, 1881 (Trematoda: Microphallidae) in the laboratory mouse

    Microsoft Academic Search

    R. A. Ahmad; B. L. James

    1987-01-01

    WhenMicrophallus pygmaeus Levinsen, 1881 was inoculated orally to laboratory mice, most specimens, failed to attach to the intestinal wall and passed out rapidly with the faeces. Those which did settle were distributed more or less evenly throughout the small intestine by 4 h after inoculation. By day 1 after inoculation the worms had developed to oviposition and most were found

  18. 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...

  19. Inspection of the handling of selected chemicals at Lawrence Livermore National Laboratory

    SciTech Connect

    Not Available

    1988-02-19

    The subject report is provided to inform of our findings and recommendations as a result of our inspection, and to give an opportunity to comment. The purpose of this inspection was to examine the potential for manufacture and/or diversion of 49 selected chemicals which were either controlled drugs or precursors that could be illegally used for the manufacture of such drugs, and to determine whether controls in place were adequate to detect misuse of these selected chemicals.

  20. Selective effects of temperature on some enzyme polymorphisms in laboratory populations of Drosophila melanogaster

    Microsoft Academic Search

    J G Oakeshott; S R Wilson; P Parnell

    1985-01-01

    In the first experiment reported here 44 isofemale lines from four recently collected base populations were each divided into three selection lines, one for each of three temperature environments—constant 23°C, constant 29°C and diurnally varying 17°C\\/29°C. Allele frequency responses after 30 generations of selection were similar across the three environments for the Adh, Gpdh and Pgm polymorphisms but differed among

  1. Vegetation-derived cues for the selection of oviposition substrates by Anopheles albimanus under laboratory conditions.

    PubMed

    Torres-Estrada, José Luis; Meza-Alvarez, R Amanda; Cibrián-Tovar, Juan; Rodríguez-López, Mario H; Arredondo-Jiménez, Juan I; Cruz-López, Leopoldo; Rojas-Leon, Julio C

    2005-12-01

    Oviposition response of gravid Anopheles albimanus Wiedemman (Diptera: Culicidae) females to water containing Brachiaria mutica, Cynodon dactylon, Jouvea straminea, Fimbristylis spadicea, and Ceratophyllum demersum was investigated. Gravid An. albimanus females deposited similar egg numbers in cups containing natural plants in water from natural breeding sites and in cups containing natural plants in distilled water. Gravid mosquitoes deposited significantly more eggs in cups containing natural plants in water from natural breeding sites than in cups containing artificial plants in water from the corresponding natural breeding sites. These results were confirmed in experiments conducted in a wind tunnel, indicating that female response is mediated by chemical cues from plants. Bioassays with organic extracts of all 5 plant species indicated that these extracts at 100%, 10%, and 1% concentrations had an oviposition repellent effect, while attractiveness was observed at 0.1%, 0.01%, and 0.001%. Gas chromatography and mass spectrometry analysis of the organic extracts found in all 5 plants showed a mixture of terpenoid and alcohol compounds, among them: guaiacol, phenol, isoeugenol, longifolene, caryophyllene, phenyl ethyl alcohol, and p-cresol. These results suggest that middle-range volatiles from plants may function as chemical cues for the female's oviposition response in this mosquito species. PMID:16506557

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

    PubMed Central

    Pelliccia, Daniele; Paganin, David M.

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2002-08-01

    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.

  4. Natural selection in utero induced by mass layoffs: the hCG evidence

    PubMed Central

    Catalano, Ralph; Margerison-Zilko, Claire; Goldman-Mellor, Sidra; Pearl, Michelle; Anderson, Elizabeth; Saxton, Katherine; Bruckner, Tim; Subbaraman, Meenakshi; Goodman, Julia; Epstein, Mollie; Currier, Robert; Kharrazi, Martin

    2012-01-01

    Evolutionary theory, when coupled with research from epidemiology, demography, and population endocrinology, suggests that contracting economies affect the fitness and health of human populations via natural selection in utero. We know, for example, that fetal death increases more among males than females when the economy unexpectedly contracts; that unexpected economic contraction predicts low secondary sex ratios; and that males from low sex ratio birth cohorts live, on average, longer than those from high sex ratio cohorts. We also know that low levels of human chorionic gonadotropin (i.e., hCG) measured in the serum of pregnant women predict fetal death. We do not, however, know whether male survivors of conception cohorts subjected to contracting economies exhibit, as theory predicts, higher hCG than those from other cohorts. We show, in 71 monthly conception cohorts including nearly two million California births, that they do. We thereby add to the literature suggesting that the economy, a phenomenon over which we collectively exercise at least some control, affects population health. Our findings imply that the effect arises via natural selection – a mechanism we largely ignore when attempting to explain, or alter, how collective choice affects our biology. PMID:23346225

  5. Complementary effect of natural and sexual selection against immigrants maintains differentiation between locally adapted fish

    NASA Astrophysics Data System (ADS)

    Plath, Martin; Riesch, Rüdiger; Oranth, Alexandra; Dzienko, Justina; Karau, Nora; Schießl, Angela; Stadler, Stefan; Wigh, Adriana; Zimmer, Claudia; Arias-Rodriguez, Lenin; Schlupp, Ingo; Tobler, Michael

    2010-08-01

    Adaptation to ecologically heterogeneous environments can drive speciation. But what mechanisms maintain reproductive isolation among locally adapted populations? Using poeciliid fishes in a system with naturally occurring toxic hydrogen sulfide, we show that (a) fish from non-sulfidic sites ( Poecilia mexicana) show high mortality (95 %) after 24 h when exposed to the toxicant, while locally adapted fish from sulfidic sites ( Poecilia sulphuraria) experience low mortality (13 %) when transferred to non-sulfidic water. (b) Mate choice tests revealed that P. mexicana females exhibit a preference for conspecific males in non-sulfidic water, but not in sulfidic water, whereas P. sulphuraria females never showed a preference. Increased costs of mate choice in sulfidic, hypoxic water, and the lack of selection for reinforcement due to the low survival of P. mexicana may explain the absence of a preference in P. sulphuraria females. Taken together, our study may be the first to demonstrate independent—but complementary—effects of natural and sexual selection against immigrants maintaining differentiation between locally adapted fish populations.

  6. Does natural selection favour taller stature among the tallest people on earth?

    PubMed

    Stulp, Gert; Barrett, Louise; Tropf, Felix C; Mills, Melinda

    2015-05-01

    The Dutch are the tallest people on earth. Over the last 200 years, they have grown 20 cm in height: a rapid rate of increase that points to environmental causes. This secular trend in height is echoed across all Western populations, but came to an end, or at least levelled off, much earlier than in The Netherlands. One possibility, then, is that natural selection acted congruently with these environmentally induced changes to further promote tall stature among the people of the lowlands. Using data from the LifeLines study, which follows a large sample of the population of the north of The Netherlands (n = 94 516), we examined how height was related to measures of reproductive success (as a proxy for fitness). Across three decades (1935-1967), height was consistently related to reproductive output (number of children born and number of surviving children), favouring taller men and average height women. This was despite a later age at first birth for taller individuals. Furthermore, even in this low-mortality population, taller women experienced higher child survival, which contributed positively to their increased reproductive success. Thus, natural selection in addition to good environmental conditions may help explain why the Dutch are so tall. PMID:25854890

  7. Complementary effect of natural and sexual selection against immigrants maintains differentiation between locally adapted fish.

    PubMed

    Plath, Martin; Riesch, Rüdiger; Oranth, Alexandra; Dzienko, Justina; Karau, Nora; Schiessl, Angela; Stadler, Stefan; Wigh, Adriana; Zimmer, Claudia; Arias-Rodriguez, Lenin; Schlupp, Ingo; Tobler, Michael

    2010-08-01

    Adaptation to ecologically heterogeneous environments can drive speciation. But what mechanisms maintain reproductive isolation among locally adapted populations? Using poeciliid fishes in a system with naturally occurring toxic hydrogen sulfide, we show that (a) fish from non-sulfidic sites (Poecilia mexicana) show high mortality (95 %) after 24 h when exposed to the toxicant, while locally adapted fish from sulfidic sites (Poecilia sulphuraria) experience low mortality (13 %) when transferred to non-sulfidic water. (b) Mate choice tests revealed that P. mexicana females exhibit a preference for conspecific males in non-sulfidic water, but not in sulfidic water, whereas P. sulphuraria females never showed a preference. Increased costs of mate choice in sulfidic, hypoxic water, and the lack of selection for reinforcement due to the low survival of P. mexicana may explain the absence of a preference in P. sulphuraria females. Taken together, our study may be the first to demonstrate independent-but complementary-effects of natural and sexual selection against immigrants maintaining differentiation between locally adapted fish populations. PMID:20574847

  8. Toxicity of Selected Chemicals to the Fairy Shrimp, Streptocephalus seali, under Laboratory and Field Conditions

    Microsoft Academic Search

    Jerry L. Moss

    1978-01-01

    Laboratory toxicity tests were conducted with six chemicals to determine their effect on fairy shrimp (Streptocephalus seali). Formalin (15 and 25 mg\\/1) and Diquat (0.25 to 2.0 mg\\/1) were not toxic to fairy shrimp. Paraquat (0.25 to 2.0 mg\\/1) and benzene hexachloride (0.10 and 0.25 mg\\/1) were moderately toxic. Dylox (0.10 and 0.25 mg\\/1) was highly toxic; mortality exceeded 82%

  9. The toxicity of selected acaricides against five stored product mites under laboratory assay

    Microsoft Academic Search

    Jitka Stará; Marta Nesvorna ´; Jan Hubert

    In laboratory tests, the toxicity of acaricides targeted against house dust mites was tested on five species of stored product\\u000a mites (Acarus siro, Aleuroglyphus ovatus, Carpoglyphus lactis, Lepidoglyphus destructor, and Tyroborus lini). The formulations of benzyl-benzoate, benzyl-benzoate\\/permethrin\\/pyriproxyfen, and neem were diluted in water and applied\\u000a to filter paper in an unventilated chamber. The mortality of mites was observed after 24 h

  10. Laboratory mating trials indicate incipient speciation by sexual selection among populations of the cichlid fish Pseudotropheus zebra from Lake Malawi.

    PubMed Central

    Knight, Mairi E.; Turner, George F.

    2004-01-01

    It has been suggested that sexual selection may have played a major role in the rapid evolution of hundreds of species of cichlid fishes in Lake Malawi. We report the results of a laboratory test of assortative mating among Lake Malawi cichlid fishes from five closely related geographical populations differing in male courtship colour. Paternity of clutches was tested using microsatellite DNA typing of offspring. Out of 1955 offspring typed, 1296 (66.3%) were sired by the male from the same population as the female, which is more than three times the rate expected if females do not differentiate among males of the different populations (20%). This result indicates that mate preferences of geographical races are strongly differentiated, consistent with the races representing incipient geographical species diverging under sexual selection exerted by female preferences for different male courtship colours. PMID:15209099

  11. Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines

    SciTech Connect

    Nigel Clark; Gregory Thompson; Richard Atkinson; Richard Turton; Chamila Tissera; Emre Tatli; Andy Zimmerman

    2005-12-28

    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

  12. Capturing naturally occurring superior performance in the laboratory: translational research on expert performance.

    PubMed

    Ericsson, K Anders; Williams, A Mark

    2007-09-01

    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 how everyday phenomena, such as successful clinical treatments and expert achievement, can be reproduced in the laboratory and how laboratory studies of these phenomena can lead to successful interventions in everyday life. The expert-performance approach was developed as a framework for capturing, analyzing, and accounting for complex acquired skills and adaptations. Performance is initially captured and elicited in the laboratory using tasks representative of core activities in the domain. Process-tracing measures are employed to identify the mechanisms that mediate the reproducibly superior performance. Finally, the factors responsible for the development of the mediating mechanisms are studied by a retrospective analysis of training activities, such as deliberate practice, as well as genetic prerequisites. The principles and mechanisms discovered need then be validated using more traditional longitudinal and experimental designs. PMID:17924797

  13. The Stochastic Evolutionary Game for a Population of Biological Networks Under Natural Selection

    PubMed Central

    Chen, Bor-Sen; Ho, Shih-Ju

    2014-01-01

    In this study, a population of evolutionary biological networks is described by a stochastic dynamic system with intrinsic random parameter fluctuations due to genetic variations and external disturbances caused by environmental changes in the evolutionary process. Since information on environmental changes is unavailable and their occurrence is unpredictable, they can be considered as a game player with the potential to destroy phenotypic stability. The biological network needs to develop an evolutionary strategy to improve phenotypic stability as much as possible, so it can be considered as another game player in the evolutionary process, ie, a stochastic Nash game of minimizing the maximum network evolution level caused by the worst environmental disturbances. Based on the nonlinear stochastic evolutionary game strategy, we find that some genetic variations can be used in natural selection to construct negative feedback loops, efficiently improving network robustness. This provides larger genetic robustness as a buffer against neutral genetic variations, as well as larger environmental robustness to resist environmental disturbances and maintain a network phenotypic traits in the evolutionary process. In this situation, the robust phenotypic traits of stochastic biological networks can be more frequently selected by natural selection in evolution. However, if the harbored neutral genetic variations are accumulated to a sufficiently large degree, and environmental disturbances are strong enough that the network robustness can no longer confer enough genetic robustness and environmental robustness, then the phenotype robustness might break down. In this case, a network phenotypic trait may be pushed from one equilibrium point to another, changing the phenotypic trait and starting a new phase of network evolution through the hidden neutral genetic variations harbored in network robustness by adaptive evolution. Further, the proposed evolutionary game is extended to an n-tuple evolutionary game of stochastic biological networks with m players (competitive populations) and k environmental dynamics. PMID:24558296

  14. Winter habitat selection of mule deer before and during development of a natural gas field

    USGS Publications Warehouse

    Sawyer, H.; Nielson, R.M.; Lindzey, F.; McDonald, L.L.

    2006-01-01

    Increased levels of natural gas exploration, development, and production across the Intermountain West have created a variety of concerns for mule deer (Odocoileus hemionus) populations, including direct habitat loss to road and well-pad construction and indirect habitat losses that may occur if deer use declines near roads or well pads. We examined winter habitat selection patterns of adult female mule deer before and during the first 3 years of development in a natural gas field in western Wyoming. We used global positioning system (GPS) locations collected from a sample of adult female mule deer to model relative frequency or probability of use as a function of habitat variables. Model coefficients and predictive maps suggested mule deer were less likely to occupy areas in close proximity to well pads than those farther away. Changes in habitat selection appeared to be immediate (i.e., year 1 of development), and no evidence of well-pad acclimation occurred through the course of the study; rather, mule deer selected areas farther from well pads as development progressed. Lower predicted probabilities of use within 2.7 to 3.7 km of well pads suggested indirect habitat losses may be substantially larger than direct habitat losses. Additionally, some areas classified as high probability of use by mule deer before gas field development changed to areas of low use following development, and others originally classified as low probability of use were used more frequently as the field developed. If areas with high probability of use before development were those preferred by the deer, observed shifts in their distribution as development progressed were toward less-preferred and presumably less-suitable habitats.

  15. The stochastic evolutionary game for a population of biological networks under natural selection.

    PubMed

    Chen, Bor-Sen; Ho, Shih-Ju

    2014-01-01

    In this study, a population of evolutionary biological networks is described by a stochastic dynamic system with intrinsic random parameter fluctuations due to genetic variations and external disturbances caused by environmental changes in the evolutionary process. Since information on environmental changes is unavailable and their occurrence is unpredictable, they can be considered as a game player with the potential to destroy phenotypic stability. The biological network needs to develop an evolutionary strategy to improve phenotypic stability as much as possible, so it can be considered as another game player in the evolutionary process, ie, a stochastic Nash game of minimizing the maximum network evolution level caused by the worst environmental disturbances. Based on the nonlinear stochastic evolutionary game strategy, we find that some genetic variations can be used in natural selection to construct negative feedback loops, efficiently improving network robustness. This provides larger genetic robustness as a buffer against neutral genetic variations, as well as larger environmental robustness to resist environmental disturbances and maintain a network phenotypic traits in the evolutionary process. In this situation, the robust phenotypic traits of stochastic biological networks can be more frequently selected by natural selection in evolution. However, if the harbored neutral genetic variations are accumulated to a sufficiently large degree, and environmental disturbances are strong enough that the network robustness can no longer confer enough genetic robustness and environmental robustness, then the phenotype robustness might break down. In this case, a network phenotypic trait may be pushed from one equilibrium point to another, changing the phenotypic trait and starting a new phase of network evolution through the hidden neutral genetic variations harbored in network robustness by adaptive evolution. Further, the proposed evolutionary game is extended to an n-tuple evolutionary game of stochastic biological networks with m players (competitive populations) and k environmental dynamics. PMID:24558296

  16. Learning Natural Selection in 4th Grade with Multi-Agent-Based Computational Models

    NASA Astrophysics Data System (ADS)

    Dickes, Amanda Catherine; Sengupta, Pratim

    2013-06-01

    In this paper, we investigate how elementary school students develop multi-level explanations of population dynamics in a simple predator-prey ecosystem, through scaffolded interactions with a multi-agent-based computational model (MABM). The term "agent" in an MABM indicates individual computational objects or actors (e.g., cars), and these agents obey simple rules assigned or manipulated by the user (e.g., speeding up, slowing down, etc.). It is the interactions between these agents, based on the rules assigned by the user, that give rise to emergent, aggregate-level behavior (e.g., formation and movement of the traffic jam). Natural selection is such an emergent phenomenon, which has been shown to be challenging for novices (K16 students) to understand. Whereas prior research on learning evolutionary phenomena with MABMs has typically focused on high school students and beyond, we investigate how elementary students (4th graders) develop multi-level explanations of some introductory aspects of natural selection—species differentiation and population change—through scaffolded interactions with an MABM that simulates predator-prey dynamics in a simple birds-butterflies ecosystem. We conducted a semi-clinical interview based study with ten participants, in which we focused on the following: a) identifying the nature of learners' initial interpretations of salient events or elements of the represented phenomena, b) identifying the roles these interpretations play in the development of their multi-level explanations, and c) how attending to different levels of the relevant phenomena can make explicit different mechanisms to the learners. In addition, our analysis also shows that although there were differences between high- and low-performing students (in terms of being able to explain population-level behaviors) in the pre-test, these differences disappeared in the post-test.

  17. David Hull's generalized natural selection as an explanation for scientific change

    NASA Astrophysics Data System (ADS)

    Little, Michelle Yvette

    2001-10-01

    Philosophers of science such as Karl Popper and Thomas Kuhn have employed evolutionary idiom in describing scientific change. In Science as a Process (1988) Hull makes evolutionary theory explanatorily applicable. He modifies key evolutionary terms in order that both biological evolution and scientific change are instances of a general selection process. According to Hull, because of naturally-existing competition for credit among researchers and the professional lineages they constitute, scientists are constrained to cooperate and collaborate. This process entails two important philosophical consequences. First, it allows for a natural justification of why the sciences can provide objective empirical knowledge. Second, appreciating its strength means that a philosophical analysis of scientific change is solidly difficult features to combine. I work on strengthening two weaknesses in Hull's arguments. First, operating in his analysis is an unexplicated notion of ``information'' running parallel to the equally opaque notion of genetic information. My third chapter provides a clear account of ``genetic information'' whose usefulness extends beyond the assistance it can render Hull as a clear concept is needed in biological contexts as well. The fourth and fifth chapters submit evidence of scientific change from radio astronomy. Hull insists on empirical backing for philosophical theses but his own book stands to suffer from selection effects as it offers cases drawn from a single subspecialty in the biological sciences. I found that in the main scientists and the change they propel accords well with Hull's explanation. However, instances of major change reveal credit- and resource-sharing to a degree contrary with what Hull would expect. My conclusion is that the naturalness of competition, instantiated during the course of standardized and relatively ``normal'' scientific research, is not the norm during periods of new research and its uncertain standards of protocol. As such my position is an inversion of the relationship Hull views between cooperation and competition in scientific change. Cooperation is a precondition for competition, rather than the other way around.

  18. On the Nature of the First Galaxies Selected at 350 Micrometers

    NASA Technical Reports Server (NTRS)

    Khan, Sophia A.; Chanial, Pierre F.; Willner, S. P.; Pearson, Chris P.; Ashby, M. L. N.; Benford, Dominic J.; Clements, David L.; Dye, Simon; Farrah, Duncan; Fazio, G. G.; Huang, J. S.; Lebouteiller, V.; Le Floc'H, Emeric; Mainetti, Gabriele; Harvey Moseley, S.; Negrello, Mattia; Serjeant, Stephen; Shafer, Richard A.; Staguhn, Johannes; Sumner, Timothy J.; Vaccari, Mattia

    2009-01-01

    We present constraints on the nature of the first galaxies selected at 350 micrometers. The sample includes galaxies discovered in the deepest blank-field survey at 350 micrometers (in the Bo6tes Deep Field) and also later serendipitous detections in the Lockman Hole. In determining multiwavelength identifications, the 350 lam position and map resolution of the second generation Submillimeter High Angular Resolution Camera are critical, especially in the cases where multiple radio sources exist and the 24 micrometer counterparts are unresolved. Spectral energy distribution templates are fitted to identified counterparts, and the sample is found to comprise IR-luminous galaxies at 1 < z < 3 predominantly powered by star formation. The first spectrum of a 350 micrometer selected galaxy provides an additional confirmation, showing prominent dust grain features typically associated with star-forming galaxies. Compared to submillimeter galaxies selected at 850 and 1100 micrometers, galaxies selected at 350 micrometers have a similar range of far-infrared color temperatures. However, no 350 micrometer selected sources are reliably detected at 850 or 1100 micrometers. Galaxies in our sample with redshifts 1 < z < 2 show a tight correlation between the far- and mid-infrared flux densities, but galaxies at higher redshifts show a large dispersion in their mid- to far-infrared colors. This implies a limit to which the mid-IR emission traces the far-IR emission in star-forming galaxies. The 350 micrometer flux densities (15 < S(sub 350) < 40 mJy) place these objects near the Herschel/SPIRE 350 micrometer confusion threshold, with the lower limit on the star formation rate density suggesting the bulk of the 350 micrometers contribution will come from less luminous infrared sources and normal galaxies. Therefore, the nature of the dominant source of the 350 micrometers background-star-forming galaxies in the epoch of peak star formation in the universe-could be more effectively probed using ground-based instruments with their angular resolution and sensitivity offering significant advantages over space-based imaging. Key words: galaxies: high-redshift galaxies: starburst infrared: galaxies submillimeter

  19. Recognition of Time-Compressed and Natural Speech with Selective Temporal Enhancements by Young and Elderly Listeners

    ERIC Educational Resources Information Center

    Gordon-Salant, Sandra; Fitzgibbons, Peter J.; Friedman, Sarah A.

    2007-01-01

    Purpose: The goal of this experiment was to determine whether selective slowing of speech segments improves recognition performance by young and elderly listeners. The hypotheses were (a) the benefits of time expansion occur for rapid speech but not for natural-rate speech, (b) selective time expansion of consonants produces greater score…

  20. Natural selection on a measure of parasite resistance varies across ages and environmental conditions in a wild mammal

    E-print Network

    Lummaa, Virpi

    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