Molecular clock
Molecular clock is a method used in molecular evolution that uses fossil constraints and their rates of molecular change to deduce the time of geologic history when the two species diverged. Evolutionary biologists investigated changes such as mutations that may change DNA genes. If results are reliable then the gene may be used as a molecular clock. Molecular clock is a powerful tool for estimating dates of a common ancestor from two species. It is also used to estimate divergence dates to calculate the rate of changes in DNA. This technique has been used to investigate other important issues such as the origin of humans to the date of the human/chimpanzee divergence.
Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species and the time since they diverged from a common ancestor. Mutations in DNA that are inherited occur at a predictable rate. The length of the lines separating species on cladograms are used to represent the estimated time since divergence. Research show evidence that mutations occur at about a constant rate so because of this, positive correlation is seen between the number of differences of two species and the time since they diverged from a common ancestor.
The molecular clock could also be used to put a series of evolutionary phenomenon into chronological order by comparing the patterns of different species to determine what common ancestor they both had. It is also useful for obtaining evolutionary information. Additionally according to the theory, the number of differences between any two gene sequences increases over time. (1962 Chemist Linus Pauling and biologist Emile Zuckerkandl)
Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species and the time since they diverged from a common ancestor. Mutations in DNA that are inherited occur at a predictable rate. The length of the lines separating species on cladograms are used to represent the estimated time since divergence. Research show evidence that mutations occur at about a constant rate so because of this, positive correlation is seen between the number of differences of two species and the time since they diverged from a common ancestor.
The molecular clock could also be used to put a series of evolutionary phenomenon into chronological order by comparing the patterns of different species to determine what common ancestor they both had. It is also useful for obtaining evolutionary information. Additionally according to the theory, the number of differences between any two gene sequences increases over time. (1962 Chemist Linus Pauling and biologist Emile Zuckerkandl)