(1) The rate at which mutations accumulate in a given genomic segment. (2) The hypothesis that, in any given gene or DNA sequence, mutations accumulate at an approximately constant rate in all evolutionary lineages as long as the gene or the DNA sequence retains its original function. The extent to which the clock applies to all genes and all organisms is controversial.
The theory that macromolecules diverge from one another over evolutionary time at a constant rate, and that discovering this rate gives insight into the phylogenetic relationships of organisms.
The hypothesis that nucleotide or amino acid substitutions occur at more or less fixed rates over evolutionary time, like the slow ticking of a clock.
A theoretical clock based on the assumption that the rates at which nucleotide (or amino acid) substitutions become fixed in evolutionary lineages is approximately constant for a given DNA sequence (or polypeptide chain) and reflects the time since data diverged.
A molecule or gene sequence that has a constant rate of change through accumulation of neutral substitutions and is therefore a good measuring stick for the relatedness of different species.
Molecular clock hypothesis - The molecular clock is a hypothesis that mutation rates and substitution rates do not vary among lineages in a tree. Therefore, if all the lineages of a tree are from the same time they should all have the same genetic distance from the root. An extension of the molecular clock concept to sequences from different times implies that the distance of a particular sequence from the root of the tree should be proportional to the amount of time that has accumulated from the root to the sampling time of that sequence. Thus a plot of root-to-tip distances against sampling times should yield a positive linear correlation with a slope equal to the mutation rate. The molecular clock hypothesis is a fundamental assumption of all models in BEAST.
A theoretical tool used by geneticists in an attempt to determine the rate at which mutations occur.
The clock-like regularity of the change of a gene over geological time.Different genetic regions may have quite different rates of change.
the postulation that the amino acid substitutions (protein clock) or nucleotide substitutions (DNA clock) occur at a constant rate for a given family of genes. Hence, the degree of genetic divergence between two species can be used to estimate the elapsed time since their divergence from a common ancestor.
An evolutionary hypothesis based on the assumption that mutations occur in a regular manner.
A constant rate of change in DNA or protein sequences as a consequence of random mutation and genetic drift of unselected molecular variants.
The molecular clock (based on the molecular clock hypothesis (MCH)) is a technique in genetics, which researchers use to date when two species diverged. It deduces elapsed time from the number of minor differences between their DNA sequences. It is sometimes called a gene clock.