Reference Work Entry

Encyclopedia of Scientific Dating Methods

Part of the series Encyclopedia of Earth Sciences Series pp 596-597


Molecular Rate Variation (Molecular Clocks)

  • Robert LanfearAffiliated withEcology, Evolution, and Genetics, The Australian National University Email author 


The rate of molecular evolution is the rate at which substitutions accumulate in an organism’s genome. Rates of molecular evolution can vary dramatically, for example, the rate of molecular evolution in some viruses is around one substitution per base pair per 1,000 years (Pagán et al., 2010), while in mammals the rate is around one substitution per base pair per 1,000 million years (Nabholz et al., 2008). Even closely related plants and animals can have rates of molecular evolution that vary by more than an order of magnitude (Thomas et al., 2006; Smith and Donoghue, 2008; Welch et al., 2008; Lanfear et al., 2013). Accounting for molecular rate variation is important in methods that use molecular sequence data to date the divergences between species (molecular dating).

There has been a great deal of research into the causes of variation in rates of molecular evolution. This research has identified a range of factors which may cause variation in the rate of molecular evolution ...

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