Genetic variance: Difference between revisions

Latest revision as of 11:26, 15 February 2025

Overview of genetic variance in populations

Introduction[edit]

Ronald Fisher, a key figure in the development of the concept of genetic variance.

Genetic variance is a measure of the genetic diversity within a population. It is a fundamental concept in the field of population genetics and plays a crucial role in the study of evolution, natural selection, and genetic drift. Genetic variance is essential for understanding how populations adapt to changing environments and how genetic diseases can be inherited.

Components of Genetic Variance[edit]

Genetic variance can be broken down into several components, each contributing to the overall genetic diversity of a population:

Additive Genetic Variance[edit]

Additive genetic variance refers to the sum of the average effects of individual alleles. It is the component of genetic variance that responds to natural selection and is responsible for the resemblance between parents and offspring.

Dominance Variance[edit]

Dominance variance arises from the interaction between alleles at a single locus. It occurs when the phenotype of the heterozygote is not exactly intermediate between the phenotypes of the homozygotes.

Epistatic Variance[edit]

Epistatic variance results from interactions between different loci. It occurs when the effect of one gene is modified by one or several other genes, which can complicate the prediction of phenotypic outcomes.

Importance in Evolution[edit]

Genetic variance is a key factor in the process of evolution. It provides the raw material upon which natural selection acts. Without genetic variance, a population cannot evolve in response to environmental changes, which can lead to extinction.

Measurement of Genetic Variance[edit]

Genetic variance is typically measured using statistical methods that partition the observed phenotypic variance into its genetic and environmental components. Techniques such as quantitative trait locus (QTL) mapping and genome-wide association studies (GWAS) are commonly used to identify the genetic basis of complex traits.

Applications[edit]

Understanding genetic variance has practical applications in fields such as agriculture, where it is used to improve crop yields and livestock breeding. In medicine, it helps in identifying genetic predispositions to diseases and developing personalized treatment plans.

Related pages[edit]

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-'''Genetic Testing''' is a type of medical test that identifies changes in [[chromosomes]], [[genes]], or [[proteins]]. The results of a genetic test can confirm or rule out a suspected genetic condition or help determine a person's chance of developing or passing on a [[genetic disorder]].
+{{short description|Overview of genetic variance in populations}}
+{{Use dmy dates|date=October 2023}}
-==Types of Genetic Testing==
+== Introduction ==
+[[File:Youngronaldfisher2.JPG|thumb|right|Ronald Fisher, a key figure in the development of the concept of genetic variance.]]
+'''Genetic variance''' is a measure of the genetic diversity within a population. It is a fundamental concept in the field of [[population genetics]] and plays a crucial role in the study of [[evolution]], [[natural selection]], and [[genetic drift]]. Genetic variance is essential for understanding how populations adapt to changing environments and how genetic diseases can be inherited.
-There are several types of genetic testing:
+== Components of Genetic Variance ==
+Genetic variance can be broken down into several components, each contributing to the overall genetic diversity of a population:
-* '''[[Diagnostic Testing]]''': Used to identify or rule out a specific genetic or chromosomal condition. In many cases, genetic testing is used to confirm a diagnosis when a particular condition is suspected based on physical signs and symptoms.
+=== Additive Genetic Variance ===
+Additive genetic variance refers to the sum of the average effects of individual alleles. It is the component of genetic variance that responds to [[natural selection]] and is responsible for the resemblance between parents and offspring.
-* '''[[Predictive and Pre-symptomatic Testing]]''': Used to detect gene mutations associated with disorders that appear after birth, often later in life. These tests can be helpful to people who have a family member with a genetic disorder, but who have no features of the disorder themselves at the time of testing.
+=== Dominance Variance ===
+Dominance variance arises from the interaction between alleles at a single locus. It occurs when the phenotype of the heterozygote is not exactly intermediate between the phenotypes of the homozygotes.
-* '''[[Carrier Testing]]''': Used to identify people who carry one copy of a gene mutation that, when present in two copies, causes a genetic disorder.
+=== Epistatic Variance ===
+Epistatic variance results from interactions between different loci. It occurs when the effect of one gene is modified by one or several other genes, which can complicate the prediction of phenotypic outcomes.
-* '''[[Prenatal Testing]]''': Used to detect changes in a fetus's genes or chromosomes before birth.
+== Importance in Evolution ==
+Genetic variance is a key factor in the process of [[evolution]]. It provides the raw material upon which [[natural selection]] acts. Without genetic variance, a population cannot evolve in response to environmental changes, which can lead to [[extinction]].
-* '''[[Newborn Screening]]''': Used just after birth to identify genetic disorders that can be treated early in life.
+== Measurement of Genetic Variance ==
+Genetic variance is typically measured using statistical methods that partition the observed phenotypic variance into its genetic and environmental components. Techniques such as [[quantitative trait locus]] (QTL) mapping and [[genome-wide association studies]] (GWAS) are commonly used to identify the genetic basis of complex traits.
-==Benefits and Risks of Genetic Testing==
+== Applications ==
+Understanding genetic variance has practical applications in fields such as [[agriculture]], where it is used to improve crop yields and livestock breeding. In [[medicine]], it helps in identifying genetic predispositions to diseases and developing personalized treatment plans.
-The potential benefits of genetic testing include a better understanding of one's genetic risk for a specific disease, the ability to make informed decisions about managing health care, and the chance to participate in medical research that could lead to new treatments or cures.
+== Related pages ==
+* [[Population genetics]]
-However, genetic testing also has potential risks and limitations. These include emotional, social, and financial impacts of test results, and potential uncertainty of results.
+* [[Natural selection]]
+* [[Genetic drift]]
-==Ethical, Legal, and Social Implications==
+* [[Quantitative genetics]]
+* [[Heritability]]
-Genetic testing raises many ethical, legal, and social issues. These include issues of privacy, confidentiality, decision-making, and responsibility for the consequences of genetic information.
-==See Also==
-* [[Genetic Counseling]]
-* [[Genetic Disorders]]
-* [[Genome Sequencing]]
-* [[Personalized Medicine]]
 [[Category:Genetics]]
-[[Category:Medical Testing]]
+[[Category:Population genetics]]
-{{Medicine-stub}}
-{{Genetics-stub}}