Sources of variation, its measurement and control
- Measurement error (reliability and validity)
- Random error (chance)
- Systematic error (bias)
- Misclassification (Information bias)
What is common cause of variation?
For a given population, there are three sources of variation: mutation, recombination, and immigration of genes. However, recombination by itself does not produce variation unless alleles are segregating already at different loci; otherwise there is nothing to recombine.
What are sources of variation in statistics?
Aug 20, 2014 · Variation in a population often results from natural selection, random genetic drift, emigration, or mutation.
What are the four sources of genetic variation?
Genetic variation is an important force in evolution as it allows natural selection to increase or decrease frequency of alleles already in the population. Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which …
What are the three types of variation?
Sampling Error. Because of the play of chance, different samples will produce different results and therefore this must be taken into account when using a sample to make inferences about a population. 2 This difference is referred to as the sampling error and its variability is measured by the standard error.
What are the 3 sources of variation in a population?
What are the 2 sources of variation in a population?
What are the main sources of this variation?
What is variation in a population?
What are types of variation?
| Continuous variation | Discontinuous variation |
|---|---|
| Height | Blood group |
| Weight | Hand used to write with |
| Arm span | Eye colour |
| Head circumference at birth | Ability to roll tongue |
What is the source of variation in a population quizlet?
What are three sources of genetic variation in a population quizlet?
What are the 4 types of variation?
What is variations in natural population?
How does geographic variation occur?
Geographic variation, or the distinctions in the genetic makeup of different populations, often occurs when populations are geographically separated by environmental barriers or when they are under selection pressures from a different environment.
What is genetic variation?
Genetic variation is a measure of the genetic differences that exist within a population. The genetic variation of an entire species is often called genetic diversity. Genetic variations are the differences in DNA segments or genes between individuals and each variation of a gene is called an allele.For example, a population with many different alleles at a single chromosome locus has a high amount of genetic variation. Genetic variation is essential for natural selection because natural selection can only increase or decrease frequency of alleles that already exist in the population.
Why is genetic variation important?
Genetic variation is an important force in evolution as it allows natural selection to increase or decrease frequency of alleles already in the population. Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes ...
What is the level of biodiversity?
genetic diversity: the level of biodiversity, refers to the total number of genetic characteristics in the genetic makeup of a species. crossing over: the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes. phenotypic variation: variation (due to underlying heritable genetic variation);
Why is genetic variation important for natural selection?
Genetic variation is essential for natural selection because natural selection can only increase or decrease frequency of alleles that already exist in the population. Genetic variation is caused by: mutation. random mating between organisms. random fertilization. crossing over (or recombination) between chromatids of homologous chromosomes ...
Why are cheetahs so low in genetic diversity?
Because wild cheetahs are threatened, their species has a very low genetic diversity. This low genetic diversity means they are often susceptible to disease and often pass on lethal recessive mutations; only about 5% of cheetahs survive to adulthood. Variation allows some individuals within a population to adapt to the changing environment.
How does gene duplication affect genetic variation?
Gene duplication, mutation, or other processes can produce new genes and alleles and increase genetic variation. New genetic variation can be created within generations in a population, so a population with rapid reproduction rates will probably have high genetic variation.
What are the different types of measurement errors?
There are several different types of measurement error, outlined below. 1. Measurement error (reliability and validity) All epidemiological investigations involve the measurement of exposures, outcomes and other characteristics of interest (e.g. potential confounding factors). Types of measures may include:
Why are confidence intervals more informative than p-values?
Confidence intervals are more informative than p-values because they provide a range of values that is likely to include the true population effect. They also indicate whether a non-significant result is, or is not, compatible with a true effect that was not detected because the sample size was too small.
What is the assumption of epidemiology?
A principal assumption in epidemiology is that we can draw an inference about the experience of the entire population based on the evaluation of a representative sample of the population. However, a problem with drawing such an inference is that the errors in measured data may affect the results of an epidemiological study. For example, the results may be influenced by the play of chance, because of the effects of random variation from sample to sample. 1 This is also important when carrying out surveys, which are addressed elsewhere in this section (see “ The design of documentation for recording survey data ”).
What is measurement error?
Measurement error (reliability and validity) All epidemiological investigations involve the measurement of exposures, outcomes and other characteristics of interest ( e.g. potential confounding factors). Types of measures may include:
What is the difference between reliability and repeatability?
Reliability, also known as reproducibility, refers to the consistency of the performance of an instrument over time and among different observers. Repeatability (also known as test-retest reliability) refers to the consistency of measurements given by a single subject, using the same instrument, under the same conditions.
What is misclassification in medical terminology?
Misclassification refers to the classification of an individual, a value or an attribute into a category other than that to which it should be assigned. 1 The misclassification of exposure or disease status can be considered as either differential or non-differential.
What is the probability of exposure being misclassified?
That is, the probability of exposure being misclassified is independent of disease status and the probability of disease status being misclassified is independent of exposure status.
What are the two sources of phenotypic variation?
Phenotypic variation arises from either of two sources: genetic variation and environmental variation. However, only differences that arise from genetic variation can be passed on to future generations. Furthermore, only a fraction of the genetic component of variation, the additive genetic variation, is actually heritable.
What is genetic variation?
Genetic variation in a population describes the existence in that population of different alleles, or alternative forms, for a given gene. The presence of genetic variation implies that individuals of the population vary in the alleles they possess, meaning that individuals differ in genotype.
Does Encyclopedia have page numbers?
Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
Why is phenotypic variation important?
Phenotypic variation is of interest to biologists because it is what natural selection acts upon: different pheno-types may have different fitnesses, and selection results in fitter phenotypes leaving more descendants. Phenotypic variation arises from either of two sources: genetic variation and environmental variation.
Is polymorphism rare?
The common view was that polymorphic loci are fairly rare. Then, the development of the technique of gel electrophoresis allowed biologists to examine patterns of protein variation across populations and to quantify genetic variation. Biologists detected surprisingly large amounts of genetic variation.
Is there genetic variation between races?
The studies in humans also revealed, famously, that so-called human races are not real biological groupings. It was found that there is considerably more genetic variation within races than between them. Since then it has been the absence of genetic variation that is considered anomalous. Absence of genetic variation in populations generally ...
How often do mutations occur?
However, mutations do not occur very frequently, only at a rate of approximately one mutation per 100,000 to 1,000,000 genetic loci per generation.
Abstract
To generalize conclusions to a population, we must sample its variation.
Main
Variability is inevitable in experiments owing to both biological and technical effects. Whereas technical variability should be tightly controlled to enhance the internal validity of the results, some types of biological variability need to be maintained to allow generalization of the results to the population of interest.
Author information
Naomi Altman is a Professor of Statistics at The Pennsylvania State University.
Integrated supplementary information
For a given layer (e.g. mouse), also shown is the variance of the mean of observations for all deeper layers (e.g. cell + technical). Xijk corresponds to the k measurement of cell j from mouse i. Dots in the subscript correspond to average over those subscripts (e.g. Xi.. is the average of cell and technical replicates for mouse i ).
About this article
Altman, N., Krzywinski, M. Sources of variation. Nat Methods 12, 5–6 (2015). https://doi.org/10.1038/nmeth.3224
What is genetic variation?
Genetic Variation. Genetic variation refers to differences among the genomes of members of the same species. A genome is all the hereditary information—all the genes—of an organism. For instance, the human genome contains somewhere between twenty and twenty-five thousand genes. Genes are units of hereditary information, ...
What is the basic unit of heredity?
Noun. change in heritable traits of a population over time. gene. Noun. part of DNA that is the basic unit of heredity. gene flow. Noun. movement and exchange of genes between interbreeding populations. genotype.
What is the genome?
A genome is all the hereditary information—all the genes—of an organism. For instance, the human genome contains somewhere between twenty and twenty-five thousand genes. Genes are units of hereditary information, and they carry instructions for building proteins. The genes that are encoded within these proteins are what enable cells to function.
Why do organisms reproduce sexually?
Most organisms that reproduce sexually have two copies of each gene, because each parent cell or organism donates a single copy of its genes to its offspring. Additionally, genes can exist in slightly different forms, called alleles, which further adds to genetic variation.
Do moths have different colors?
An example would be moths of the same species with different color wings. Moths with wings similar to the color of tree bark are better able to camouflage themselves than moths of a different color. As a result, the tree-colored moths are more likely to survive, reproduce, and pass on their genes.
What is the definition of environment?
Noun. (deoxyribonucleic acid) molecule in every living organism that contains specific genetic information on that organism. environment. Noun. conditions that surround and influence an organism or community. evolution. Noun. change in heritable traits of a population over time. gene.
What is the meaning of "genes"?
movement and exchange of genes between interbreeding populations. genotype. Noun. genetic makeup on an individual organism. heredity. Noun. the passing on of characteristics from ancestors to descendants. mutation. Noun.
