if you want to remove an article from website contact us from top.

    which of the following best defines a gene pool? the sum of all genetic traits in a population’s individuals at a given time any movement of genes from one population to another any movement of organisms from one environment to another the random change in the frequency of an allele in a population

    James

    Guys, does anyone know the answer?

    get which of the following best defines a gene pool? the sum of all genetic traits in a population’s individuals at a given time any movement of genes from one population to another any movement of organisms from one environment to another the random change in the frequency of an allele in a population from EN Bilgi.

    gene flow

    gene pool, sum of a population’s genetic material at a given time. The term typically is used in reference to a population made up of individuals of the same species and includes all genes and combinations of genes (sum of the alleles) in the population. The composition of a population’s gene pool can change over time through evolution. This can occur by a variety of mechanisms, including mutations, natural selection, and genetic drift. The result is a gene pool that is altered to be attuned to the needs of the population’s specific environment. For example, the migration of human populations

    gene pool

    genetics

    By Omar Sultan Haque • Edit History

    Related Topics: population genetics isolate

    See all related content →

    gene pool, sum of a population’s genetic material at a given time. The term typically is used in reference to a population made up of individuals of the same species and includes all genes and combinations of genes (sum of the alleles) in the population.

    The composition of a population’s gene pool can change over time through evolution. This can occur by a variety of mechanisms, including mutations, natural selection, and genetic drift. The result is a gene pool that is altered to be attuned to the needs of the population’s specific environment. For example, the migration of human populations from equatorial regions toward northern climates, where they were exposed to relatively low amounts of sunlight, resulted in changes over time in skin pigmentation, with skin becoming lighter in colour to augment vitamin D absorption (vitamin D is critical for proper bone development). The genetic modifications underlying the change in pigmentation ultimately became a part of many of those populations’ gene pools.

    READ MORE ON THIS TOPIC

    evolution: The gene pool

    The gene pool is the sum total of all the genes and combinations of genes that occur in a population of organisms of the...

    The ability of a population to adapt and evolve is thought to be influenced in part by the size of its gene pool. A large and diverse gene pool, for example, may improve a population’s chances for future adaptation to changing environmental conditions. Populations with smaller, narrower gene pools, on the other hand, may be less successful when confronted with swift environmental change.

    Omar Sultan Haque

    The Editors of Encyclopaedia Britannica

    natural selection

    natural selection

    biology

    By The Editors of Encyclopaedia Britannica • Edit History

    Charles Darwin: On the Origin of Species

    See all media

    Key People: Charles Darwin Alfred Russel Wallace Patrick Matthew Francisco J. Ayala H.W. Bates

    Related Topics: survival of the fittest adaptation sexual selection group selection Darwinian fitness

    See all related content →

    natural selection, process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution.

    A brief treatment of natural selection follows. For full treatment, see evolution: The concept of natural selection.

    READ MORE ON THIS TOPIC

    evolution: The concept of natural selection

    The central argument of Darwin’s theory of evolution starts with the existence of hereditary variation. Experience with animal and plant...

    In natural selection, those variations in the genotype (the entire complex of genes inherited from both parents) that increase an organism’s chances of survival and procreation are preserved and multiplied from generation to generation at the expense of less advantageous variations. Evolution often occurs as a consequence of this process. Natural selection may arise from differences in survival, in fertility, in rate of development, in mating success, or in any other aspect of the life cycle. All such differences result in natural selection to the extent that they affect the number of progeny an organism leaves.

    Gene frequencies tend to remain constant from generation to generation when disturbing factors are not present. Factors that disturb the natural equilibrium of gene frequencies include mutation, migration (or gene flow), random genetic drift, and natural selection. A mutation is a spontaneous change in the gene frequency that takes place in a population and occurs at a low rate. Migration is a local change in gene frequency when an individual moves from one population to another and then interbreeds. Random genetic drift is a change that takes place from one generation to another by a process of pure chance. Mutation, migration, and genetic drift alter gene frequencies without regard to whether such changes increase or decrease the likelihood of an organism surviving and reproducing in its environment. They are all random processes.

    New from Britannica

    NASA engineers asked Sally Ride if she needed 100 tampons for her first trip into space, which lasted six days.

    See All Good Facts

    Natural selection moderates the disorganizing effects of these processes because it multiplies the incidence of beneficial mutations over the generations and eliminates harmful ones, since their carriers leave few or no descendants. Natural selection enhances the preservation of a group of organisms that are best adjusted to the physical and biological conditions of their environment and may also result in their improvement in some cases. Some characteristics, such as the male peacock’s tail, actually decrease the individual organism’s chance of survival. To explain such anomalies, Darwin posed a theory of “sexual selection.” In contrast to features that result from natural selection, a structure produced by sexual selection results in an advantage in the competition for mates.

    The Editors of Encyclopaedia Britannica

    Source : www.britannica.com

    The Variety of Genes in the Gene Pool Can Be Quantified within a Population

    Genes exist in multiple forms called alleles, which vary in quantity between different groups of organisms.

    The Variety of Genes in the Gene Pool Can Be Quantified within a Population

    Most populations have some degree of variation in their gene pools. By measuring the amount of genetic variation in a population, scientists can begin to make predictions about how genetic variation changes over time. These predictions can then help them gain important insights into the processes that allow organisms to adapt to their environment or to develop into new species over generations, also known as the process of evolution.

    Genetic variation is usually expressed as a relative frequency, which means a proportion of the total population under study. In other words, a relative frequency value represents the percentage of a given phenotype, genotype, or allele within a population.

    Relative phenotype frequency is the number of individuals in a population that have a specific observable trait or phenotype. To compare different phenotype frequencies, the relative phenotype frequency for each phenotype can be calculated by counting the number of times a particular phenotype appears in a population and dividing it by the total number of individuals in the population.Relative genotype frequency and relative allele frequency are the most important measures of genetic variation. Relative genotype frequency is the percentage of individuals in a population that have a specific genotype. The relative genotype frequencies show the distribution of genetic variation in a population. Relative allele frequency is the percentage of all copies of a certain gene in a population that carry a specific allele. This is an accurate measurement of the amount of genetic variation in a population.

    Examining allele frequencies

    A gene that can occur in two forms is said to have two alleles. Body color in fruit flies is an example of a gene with two alleles: a dominant allele for brown body color, and a recessive allele for black body color. The brown body color allele can be represented as "B" and the black body color allele as "b." The allele frequencies for a gene with two alleles are usually represented by the letters p and q, where the relative frequency of the B allele is p and the relative frequency of the b allele is q.

    Symbolically, these relative allele frequencies can be represented as:

    relative frequency (B) = p and relative frequency (b) = q

    Remember the Punnett square?

    Figure 1: A Punnett square showing how p and q alleles combine.

    Figure Detail

    If B and b are the only two alleles of a gene, then possible genotypes can be predicted by arranging the alleles in a Punnett square, in their p and q representation (Figure 1). This exercise can help to visualize the computation of relative allele frequencies and their corresponding relative genotype frequencies in a population.

    The possible combinations can be represented mathematically as:

    [p × p] + [2 × p × q] + [q × q]

    or p2 + 2pq + q2

    How can relative frequencies be used to study populations?

    The mathematical expression p2 + 2pq + q2 can be used as a platform for understanding both allele frequencies and genotype frequencies in real populations. For instance, if a population does not change over time, then scientists can make certain predictions about its relative allele frequencies, and about its relative genotype frequencies. In other words, if they have information about its relative genotype frequencies, they may also make predictions about its relative allele frequencies.

    When a population is in equilibrium, the BB homozygotes (individuals that carry the same two dominant B alleles) will have a relative genotype frequency of p2: freq (BB) = p2. Similarly, bb homozygotes (individuals that carry the same two recessive b alleles) will have a relative genotype frequency of q2: freq (bb) = q2. Finally, the Bb heterozygotes (individuals that carry both the dominant B allele and the recessive b allele) will have a relative genotype frequency of 2pq: freq (Bb) = 2pq.

    In a stable population, the sum of all these relative genotype frequencies remains equal to 1 over successive generations. This is a mathematical way of expressing that the sum of all relative genotype frequencies always equals 1 because if one relative genotype frequency increases, another will decrease in tandem, and alleles become redistributed rather than increasing in proportion to the population. Therefore, this relationship can be expressed mathematically as follows:

    This equation is known as the Hardy-Weinberg equation, and it defines a population in which relative allele frequencies do not change over successive generations. Such a population is said to be in equilibrium. This state of equilibrium represented by the Hardy-Weinberg equation is an ideal model against which to compare observed changes in relative allele and genotype frequencies in natural populations.

    How is the Hardy-Weinberg equation used?

    The Hardy-Weinberg equation describes a population at equilibrium. This can only occur in the absence of disturbing factors and when mating between individuals is completely random. When mating is random in a large population, both the relative genotype and allele frequencies will remain constant.

    Source : www.nature.com

    Allele frequency & the gene pool (article)

    How to find allele frequency and how it's different from genotype frequency. What a gene pool is.

    Key points:

    Microevolution is a change in the frequency of gene variants, alleles, in a population, typically occurring over a relatively short time period.Population genetics is the field of biology that studies allele frequencies in populations and how they change over time.Allele frequency refers to how common an allele is in a population. It is determined by counting how many times the allele appears in the population then dividing by the total number of copies of the gene.

    \text{Frequency of allele }A

    Frequency of allele A

    start text, F, r, e, q, u, e, n, c, y, space, o, f, space, a, l, l, e, l, e, space, end text, A

    = = equals

    \dfrac{{\text{Number of copies of allele }A \:{\text {in population}}}}{\text{Total number of }{\text{copies of gene in population}}}

    Total number of copies of gene in population

    Number of copies of allele Ain population

    start fraction, start text, N, u, m, b, e, r, space, o, f, space, c, o, p, i, e, s, space, o, f, space, a, l, l, e, l, e, space, end text, A, start text, i, n, space, p, o, p, u, l, a, t, i, o, n, end text, divided by, start text, T, o, t, a, l, space, n, u, m, b, e, r, space, o, f, space, end text, start text, c, o, p, i, e, s, space, o, f, space, g, e, n, e, space, i, n, space, p, o, p, u, l, a, t, i, o, n, end text, end fraction

    The gene pool of a population consists of all the copies of all the genes in that population.

    Darwin meets Mendel—not literally

    When Darwin came up with his theories of evolution and natural selection, he knew that the processes he was describing depended on heritable variation in populations. That is, they relied on differences in the features of the organisms in a population and on the ability of these different features to be passed on to offspring.

    [Read a quick recap of evolution and natural selection.]

    Darwin did not, however, know how traits were inherited. Like other scientists of his time, he thought that traits were passed on via blending inheritance. In this model, parents' traits are supposed to permanently blend in their offspring. The blending model was disproven by Austrian monk Gregor Mendel, who found that traits are specified by non-blending heritable units called genes.

    Although Mendel published his work on genetics just a few years after Darwin published his ideas on evolution, Darwin probably never read Mendel’s work. Today, we can combine Darwin’s and Mendel’s ideas to arrive at a clearer understanding of what evolution is and how it takes place.

    Microevolution and population genetics

    Microevolution, or evolution on a small scale, is defined as a change in the frequency of gene variants, alleles, in a population over generations. The field of biology that studies allele frequencies in populations and how they change over time is called population genetics.

    Microevolution is sometimes contrasted with macroevolution, evolution that involves large changes, such as formation of new groups or species, and happens over long time periods. However, most biologists view microevolution and macroevolution as the same process happening on different timescales. Microevolution adds up gradually, over long periods of time to produce macroevolutionary changes.

    Let's look at three concepts that are core to the definition of microevolution: populations, alleles, and allele frequency.

    Populations

    A population is a group of organisms of the same species that are found in the same area and can interbreed. A population is the smallest unit that can evolve—in other words, an individual can’t evolve.

    Alleles

    An allele is a version of a gene, a heritable unit that controls a particular feature of an organism.

    For instance, Mendel studied a gene that controls flower color in pea plants. This gene comes in a white allele, w, and a purple allele, W. Each pea plant has two gene copies, which may be the same or different alleles. When the alleles are different, one—the dominant allele, W—may hide the other—the recessive allele, w. A plant's set of alleles, called its genotype, determines its phenotype, or observable features, in this case flower color.

    Phenotype—flower color Genotype—pair of alleles

    W—dominant purple allele w—recessive white allele

    WW—purple flower Ww—purple flower ww—white flower

    Allele frequency

    Allele frequency refers to how frequently a particular allele appears in a population. For instance, if all the alleles in a population of pea plants were purple alleles, W, the allele frequency of W would be 100%, or 1.0. However, if half the alleles were W and half were w, each allele would have an allele frequency of 50%, or 0.5.

    In general, we can define allele frequency as

    \text{Frequency of allele }A

    Frequency of allele A

    start text, F, r, e, q, u, e, n, c, y, space, o, f, space, a, l, l, e, l, e, space, end text, A

    = = equals

    \dfrac{{\text{Number of copies of allele }A \:{\text {in population}}}}{\text{Total number of}\:{A/a}{\text{ gene copies in population}}}

    Source : www.khanacademy.org

    Do you want to see answer or more ?
    James 7 month ago
    4

    Guys, does anyone know the answer?

    Click For Answer