Selection

(noun)

Stage one of the perception process, and the process by which we attend to some stimuli in our environment and not others.

Related Terms

Examples of Selection in the following topics:

  • Stabilizing, Directional, and Diversifying Selection

    • If natural selection favors an average phenotype by selecting against extreme variation, the population will undergo stabilizing selection.
    • When the environment changes, populations will often undergo directional selection, which selects for phenotypes at one end of the spectrum of existing variation.
    • Sometimes natural selection can select for two or more distinct phenotypes that each have their advantages.
    • Diversifying selection occurs when extreme values for a trait are favored over the intermediate values.This type of selection often drives speciation.
    • Different types of natural selection can impact the distribution of phenotypes within a population.In (a) stabilizing selection, an average phenotype is favored.In (b) directional selection, a change in the environment shifts the spectrum of phenotypes observed.In (c) diversifying selection, two or more extreme phenotypes are selected for, while the average phenotype is selected against.

  • Natural Selection and Adaptive Evolution

    • Natural selection drives adaptive evolution by selecting for and increasing the occurrence of beneficial traits in a population.
    • Natural selection only acts on the population's heritable traits: selecting for beneficial alleles and, thus, increasing their frequency in the population, while selecting against deleterious alleles and, thereby, decreasing their frequency.
    • Natural selection does not act on individual alleles, however, but on entire organisms.
    • Natural selection acts at the level of the individual; it selects for individuals with greater contributions to the gene pool of the next generation, known as an organism's evolutionary fitness (or Darwinian fitness).
    • Through natural selection, a population of finches evolved into three separate species by adapting to several difference selection pressures.

  • Clonal Selection and Tolerance

    • Clonal selection and tolerance select for survival of lymphocytes that will protect the host from foreign antigens.
    • Clonal selection occurs after immature lymphocytes express antigen receptors.
    • The preservation of useful specificities is called positive selection.
    • Negative selection of developing lymphocytes is an important mechanism for maintaining central tolerance.
    • clonal selection of the B and T lymphocytes:1.

  • Selective and Differential Media

    • Selective media are used for the growth of only selected microorganisms.
    • Selective growth media for eukaryotic cells commonly contain neomycin to select cells that have been successfully transfected with a plasmid carrying the neomycin resistance gene as a marker.
    • Some examples of selective media include:
    • Mannitol salt agar (MSA) which is selective for Gram-positive bacteria and differential for mannitol.
    • Xylose lysine desoxyscholate (XLD), which is selective for Gram-negative bacteria buffered charcoal yeast extract agar, which is selective for certain gram-negative bacteria, especially Legionella pneumophila.

  • Employee Selection

    • However, it most commonly refers to the selection of workers.
    • A selection system should depend on job analysis.
    • This ensures that the selection criteria are job related and propose value additions for the organization.
    • The selection ratio (SR) is the number of job openings (n) divided by the number of job applicants (N).
    • Break down the human resource selection process as organizations pursue new employee talent

  • Frequency-Dependent Selection

    • In frequency-dependent selection, phenotypes that are either common or rare are favored through natural selection.
    • Another type of selection, called frequency-dependent selection, favors phenotypes that are either common (positive frequency-dependent selection) or rare (negative frequency-dependent selection).
    • An interesting example of this type of selection is seen in a unique group of lizards of the Pacific Northwest.
    • In this scenario, orange males will be favored by natural selection when the population is dominated by blue males, blue males will thrive when the population is mostly yellow males, and yellow males will be selected for when orange males are the most populous.
    • Negative frequency-dependent selection serves to increase the population's genetic variance by selecting for rare phenotypes, whereas positive frequency-dependent selection usually decreases genetic variance by selecting for common phenotypes.

  • The Perceptual Process

    • Personality - Personality traits influence how a person selects perceptions.
    • Size - A larger size makes it more likely an object will be selected.
    • Motion - A moving perception is more likely to be selected.
    • Novelty and familiarity - Both of these increase selection.
    • After certain perceptions are selected, they can be organized differently.

  • No Perfect Organism

    • Natural selection cannot create novel, perfect species because it only selects on existing variations in a population.
    • However, natural selection cannot produce the perfect organism.
    • Natural selection can only select on existing variation in the population; it cannot create anything from scratch.
    • Natural selection is also limited because it acts on the phenotypes of individuals, not alleles.
    • This a common example of disruptive selection.

  • Theories of Life History

    • The regulation of population growth by these factors can be used to introduce a classical concept in population biology: that of K-selected versus r-selected species.
    • For this analysis, population biologists have grouped species into the two large categories, K-selected and r-selected, although they are really two ends of a continuum.
    • K-selected species are those in stable, predictable environments.
    • Populations of K-selected species tend to exist close to their carrying capacity (hence the term K-selected) where intraspecific competition is high.
    • In contrast to K-selected species, r-selected species have a large number of small offspring (hence their r designation).

  • Expect Selective Exposure

    • People can determine the information exposed to them and select favorable evidence, while ignoring the unfavorable.
    • Selective exposure influences and family, friends, co-workers, even skilled professionals like doctors.
    • Media forms such as the internet, television, and paper sources are also inclined to selective bias.
    • Selective exposure can interfere or prevent the gathering of new information.
    • Selective exposure is prevalent in both groups of people and individually.