Molecular drive
Encyclopedia
Adoptation redirects here and should not be confused with adaptation
Molecular drive is a term coined by Gabriel Dover
in 1982 to describe evolution
ary processes that change the genetic composition of a population
through DNA turnover mechanisms. Molecular drive operates independently of natural selection
and genetic drift
.
The best-known such process is the concerted evolution
of gene
s present in many tandem copies, such as those for ribosomal RNA
s or silk moth
egg shell chorion
proteins, in sexually reproducing
species. The concept has been proposed to extend to the diversification of multigene families
. The mechanisms involved include gene conversion
, unequal crossing-over, transposition
, slippage replication
and RNA-mediated exchanges. Because mutation
s changing the sequence of one copy are less common than deletions, duplications
and replacement of one copy by another, the copies gradually come to resemble each other much more than they would if they had been evolving independently.
Concerted evolution can be unbiased, in which case every version has an equal probability of being the one that replaces the others. However, if the molecular events have any bias favouring one version of the sequence over others, that version will dominate the process and eventually replace the others. The name 'molecular drive' reflects the similarity of the process with what was originally the better-known process of meiotic drive.
Molecular drive can also act in bacteria
, where parasexual processes such as natural transformation
cause DNA turnover.
, TRAM is a genetic system that has features of Non-mendelian inheritance
Turnover, copy number and functional Redundancy And Modulatory. To date all regulatory regions (promoters) and gen
es, that have been examined in detail at the molecular level, have TRAM characteristics. As such, part of their evolutionary history will have been influenced by the molecular drive
process.
, Adoptation is an evolved feature of an organism that contributes to its viability and reproduction (established by molecular drive
) and that adopts some previously inaccessible component of the environment.
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
Molecular drive is a term coined by Gabriel Dover
Gabriel Dover
Gabriel A. Dover is a British geneticist. He is best known for coining the term molecular drive in 1982 to describe a putative third evolutionary force operating distinctly from natural selection and genetic drift...
in 1982 to describe evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
ary processes that change the genetic composition of a population
Population
A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...
through DNA turnover mechanisms. Molecular drive operates independently of natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
and genetic drift
Genetic drift
Genetic drift or allelic drift is the change in the frequency of a gene variant in a population due to random sampling.The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces...
.
The best-known such process is the concerted evolution
Concerted evolution
Concerted evolution is a process that may explain the observation that paralogous genes within one species are more closely related to each other than to members of the same gene family in another species, even though the gene duplication event preceded the speciation event...
of gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s present in many tandem copies, such as those for ribosomal RNA
Ribosomal RNA
Ribosomal ribonucleic acid is the RNA component of the ribosome, the enzyme that is the site of protein synthesis in all living cells. Ribosomal RNA provides a mechanism for decoding mRNA into amino acids and interacts with tRNAs during translation by providing peptidyl transferase activity...
s or silk moth
Bombyx mori
The silkworm is the larva or caterpillar of the domesticated silkmoth, Bombyx mori . It is an economically important insect, being a primary producer of silk...
egg shell chorion
Chorion
The chorion is one of the membranes that exist during pregnancy between the developing fetus and mother. It is formed by extraembryonic mesoderm and the two layers of trophoblast and surrounds the embryo and other membranes...
proteins, in sexually reproducing
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
species. The concept has been proposed to extend to the diversification of multigene families
Protein family
A protein family is a group of evolutionarily-related proteins, and is often nearly synonymous with gene family. The term protein family should not be confused with family as it is used in taxonomy....
. The mechanisms involved include gene conversion
Gene conversion
Gene conversion is an event in DNA genetic recombination, which occurs at high frequencies during meiotic division but which also occurs in somatic cells. It is a process by which DNA sequence information is transferred from one DNA helix to another DNA helix, whose sequence is altered.It is one...
, unequal crossing-over, transposition
Transposon
Transposable elements are sequences of DNA that can move or transpose themselves to new positions within the genome of a single cell. The mechanism of transposition can be either "copy and paste" or "cut and paste". Transposition can create phenotypically significant mutations and alter the cell's...
, slippage replication
Slipped strand mispairing
Slipped strand mispairing is a mutation process which occurs during DNA replication. It involves denaturation and displacement of the DNA strands, resulting in mispairing of the complementary bases. Slipped strand mispairing is one explanation for the origin and evolution of repetitive DNA sequences...
and RNA-mediated exchanges. Because mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
s changing the sequence of one copy are less common than deletions, duplications
Gene duplication
Gene duplication is any duplication of a region of DNA that contains a gene; it may occur as an error in homologous recombination, a retrotransposition event, or duplication of an entire chromosome.The second copy of the gene is often free from selective pressure — that is, mutations of it have no...
and replacement of one copy by another, the copies gradually come to resemble each other much more than they would if they had been evolving independently.
Concerted evolution can be unbiased, in which case every version has an equal probability of being the one that replaces the others. However, if the molecular events have any bias favouring one version of the sequence over others, that version will dominate the process and eventually replace the others. The name 'molecular drive' reflects the similarity of the process with what was originally the better-known process of meiotic drive.
Molecular drive can also act in bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, where parasexual processes such as natural transformation
Transformation (genetics)
In molecular biology transformation is the genetic alteration of a cell resulting from the direct uptake, incorporation and expression of exogenous genetic material from its surroundings and taken up through the cell membrane. Transformation occurs naturally in some species of bacteria, but it can...
cause DNA turnover.
TRAM
According to Gabriel A. DoverGabriel Dover
Gabriel A. Dover is a British geneticist. He is best known for coining the term molecular drive in 1982 to describe a putative third evolutionary force operating distinctly from natural selection and genetic drift...
, TRAM is a genetic system that has features of Non-mendelian inheritance
Non-mendelian inheritance
Non-Mendelian inheritance is a general term that refers to any pattern of inheritance in which traits do not segregate in accordance with Mendel’s laws. These laws describe the inheritance of traits linked to single genes on chromosomes in the nucleus. In Mendelian inheritance, each parent...
Turnover, copy number and functional Redundancy And Modulatory. To date all regulatory regions (promoters) and gen
Gen
Gen may refer to:* Gen , 2006 Turkish horror film directed by Togan Gökbakar* Gen language, the language of Togo* Gen , a video game character from the Street Fighter series...
es, that have been examined in detail at the molecular level, have TRAM characteristics. As such, part of their evolutionary history will have been influenced by the molecular drive
Molecular drive
Adoptation redirects here and should not be confused with adaptationMolecular drive is a term coined by Gabriel Dover in 1982 to describe evolutionary processes that change the genetic composition of a population through DNA turnover mechanisms...
process.
Adoptation
According to Gabriel A. DoverGabriel Dover
Gabriel A. Dover is a British geneticist. He is best known for coining the term molecular drive in 1982 to describe a putative third evolutionary force operating distinctly from natural selection and genetic drift...
, Adoptation is an evolved feature of an organism that contributes to its viability and reproduction (established by molecular drive
Molecular drive
Adoptation redirects here and should not be confused with adaptationMolecular drive is a term coined by Gabriel Dover in 1982 to describe evolutionary processes that change the genetic composition of a population through DNA turnover mechanisms...
) and that adopts some previously inaccessible component of the environment.
Key papers
- Dover GA (1982) Molecular drive: A cohesive mode of species evolution. Nature 299: 111–117
- Dover GA (1986) Molecular drive in multigene families: how biological novelties arise, spread and are assimilated. Trends Genet 159–165 (Review)