Molecular clock - dnareplicationsystem - Google Sites

Ho SY and Larson G (2006) Molecular clocks: when times are a‐changin. Trends in Genetics 22: 79–83.

PPT – Molecular Clock Hypothesis PowerPoint …

Abstract: Although interest in the rate of molecular evolution and the molecular clock remains high, our knowledge for most groups in these areas is derived largely from a patchwork of studies limited in both their taxon coverage and the num-ber of genes examined.

Kumar S (2005) Molecular clocks: four decades of evolution. Nature Reviews Genetics 6: 654–662.

The Molecular Clock Hypothesis: Biochemical …

Bromham L, Penny D, Rambaut A and Hendy MD (2000) The power of relative rates tests depends on the data. Journal of Molecular Evolution 50: 296–301.

Cutler DJ (2000) Estimating divergence times in the presence of an overdispersed molecular clock. Molecular Biology and Evolution 17: 1647–1660.


Bayesian molecular clock dating of species divergences …

Originally, the possibility was explored that all of thevariables influencing DNA replication error-rate might cancelsomewhat and show some level of constancy when averaged over time,across species and over parts of the . Because the enzymes that replicate DNAonly vary slightly between species, the assumption might haveseemed reasonable to Pauling or Zuckerkandl asbiochemists. This pioneering effort to integrate the fields ofevolutionary and molecular biology can be said to have set asidethe variation in rate of DNA repair and in time, space, and across until molecular evidenceaccumulated enough to make those variations suitable topics ofstudy in their own light. While the MCH cannot be blindly assumedto be true, individual molecular clocks can be tested foraccuracy and utilized in many cases. In general terms, they need tobe against material evidence such as fossils before firm conclusionscan be based on them (see also Lovette).Measures in regions of low selection (silent substitutions) showedrates of 0.7-0.8% per inbacteria, mammals, invertebrates, and plants.In the same study, genomic regions of very high selection (encodingrRNA) were considerably slower (1% per 50 Myr).

Molecular Clocks - eLS: Essential for Life Science

Molecular clock users have developed workaround solutions usinga number of statistical approaches including techniques and later . In particular, models that take into account ratevariation across lineages have been proposed in order to obtainbetter estimates of divergence times (and other parameters that maybe estimated from substitution rates, such as effective populationsize.) These models are called relaxed molecularclocksbecause they represent an intermediate position between the'strict' molecular clock hypothesis and Felsenstein's many-ratesmodel and are made possible through techniques that explore aweighted range of tree topologies and simultaneously estimateparameters of the chosen substitution model. It must be rememberedthat these are still based on statistical and not on direct and that therefore, even a relaxed molecular clock can only support butnever a scientific hypothesis. Thisproblem is approached by using the , whichquite often is good and well-documented enough to provide hardevidence, to calibrate the molecular clock accordingly.Alternatively, for viral phylogenetics and studies, two areas ofevolutionary biology where it is possible to sample sequences overan evolutionary timescale, the dates of the sequence themselves canbe used to calibrate the molecular clock.

Molecular Clock Test (ML) - MEGA, Molecular …

The molecular clock technique is an important tool in , the use of information to determine the correct of organisms orto study variation in selective forces.