molecular clock


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molecular clock

n.
1. An assumed approximately constant rate of change over evolutionary time in the nucleotide sequences of DNA molecules and the amino acid sequences of protein molecules.
2. A technique based on this assumption, in which the amount of time since two species or other taxa diverged from a common ancestor is estimated by measuring the number of differences between certain gene or protein sequences of the taxa.
References in periodicals archive ?
Complete genomic sequence of human coronavirus OC43: molecular clock analysis suggests a relatively recent zoonotic coronavirus transmission event.
That scenario would interfere with the molecular clock, making it impossible to retrieve a reliable mutation rate from the Y chromosome, they acknowledge.
Thus, a male-biased mutation rate will lead to proportionally fewer genetic changes on the X and will seem to be younger when using a molecular clock, even if all the chromosomes diverged at around the same time, the researchers argue.
A molecular clock of ORF3 suggests that the common ancestor of the European type of PRRSV infected domestic pigs around 1979 (31).
Such molecular clock analyses often clash with standard ideas about the timing of a species' origin (SN: 6/28/97, p.
By treating the mitochondrial DNA of contemporary Indians as a sort of molecular clock, the researchers documented an expansion in Indian genetic diversity dated to around the time of this ice age.
To determine whether Peruvian YFVs were characterized by a single homogeneous rate of nucleotide substitution (i.e., a molecular clock), we performed a series of likelihood ratio tests using the PAUP* software analysis package.
Washington, June 5 (ANI): Researchers at the University of Leeds, UK, have devised a new 'molecular clock' that aids dating of human migration history.
To construct their molecular clock, the Stony Brook scientists analyzed the DNA sequences of seven genes in living animals.
The researchers used the two existing fossil seahorses to calibrate the rate of evolution of DNA in their molecular clock.
But they could provide scientists with much-needed information about the mutation rate of DNA, a so-called molecular clock used to decipher evolutionary relationships among organisms.
To their surprise, they found that the independently estimated 'molecular clock' of the monkey viruses was virtually identical to the famously swift rate at which mutations accumulate in HIV genomes.
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