Related Experiment Video

Updated: Aug 8, 2026

Assessing Differences in Sperm Competitive Ability in Drosophila
09:34

Assessing Differences in Sperm Competitive Ability in Drosophila

Published on: August 22, 2013

Gene flow and selection in a natural population of Drosophila melanogaster

J A McKenzie

    Genetics
    |June 1, 1975
    PubMed

    More Related Videos

    Maintenance of a Drosophila melanogaster Population Cage08:03

    Maintenance of a Drosophila melanogaster Population Cage

    Published on: March 15, 2016

    Rearing the Fruit Fly Drosophila melanogaster Under Axenic and Gnotobiotic Conditions09:34

    Rearing the Fruit Fly Drosophila melanogaster Under Axenic and Gnotobiotic Conditions

    Published on: July 30, 2016

    Related Concept Videos

    What is Natural Selection?01:32

    What is Natural Selection?

    Natural selection is an evolutionary process in which individuals with survival-promoting traits reproduce at higher rates. These favorable traits become more common within a population or species. Naturally selected traits initially arise via random genetic mutations. In order for selection to occur, there must be variation within a population, the trait controlling the variation must be heritable, and there must be an evolutionary advantage for variation in the trait.The Theory of Natural...
    Types of Selection01:46

    Types of Selection

    Natural selection influences the frequencies of particular alleles and phenotypes within populations in several different ways. Primarily, natural selection can be directional, stabilizing, or disruptive. Directional selection favors one extreme trait and shifts the population towards that phenotype while selecting against individuals displaying alternate traits. Stabilizing selection favors an intermediate trait with a narrow range of variation. Deviation from the optimal phenotype towards an...
    Frequency-dependent Selection01:21

    Frequency-dependent Selection

    When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.Positive Frequency-Dependent SelectionIn positive...
    Mutation, Gene Flow, and Genetic Drift01:09

    Mutation, Gene Flow, and Genetic Drift

    In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size).Mechanisms of Genetic VariationThe original sources of genetic variation are mutations,...
    Genetic Drift03:33

    Genetic Drift

    Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.Life is not fair. A deer grazing contentedly in a field can have her meal cut tragically short by a bolt of lightning. If the doomed doe is one of only three in the population, 1/3 of the population’s gene pool is lost. Random events like this can...
    Gene Flow02:39

    Gene Flow

    Gene flow is the transfer of genes among populations, resulting from either the dispersal of gametes or from the migration of individuals.