Molecular Clock Calculator
Calculate divergence time from sequence divergence rate. Molecular clock: T = D / (2r). Date speciation events and calibrate evolutionary timelines from DNA sequence data.
🧬 Molecular Evolution📐 T = D / (2 x mutation rate)🧬 Biology
Sequence divergence % (or fraction)
Mutation rate (subs/site/year)
Please enter valid values.
Formula & Reference
| Variable | Symbol | Formula | Units |
|---|---|---|---|
| Molecular Clock Calculator | — | T = D / (2 x mutation rate) | million years (Ma) |
Step-by-Step Examples
Example 1
Human-Chimp mtDNA
5.2% divergence, rate=0.02 subs/site/yr.
- T = 0.052/(2x0.02) = 1.3 Ma
- Actual split ~6 Ma by fossils
- Nuclear DNA clock more accurate
✓ 1.3 Ma (mtDNA estimate)
Example 2
Bacterial Outbreak
0.1% divergence, rate=0.001/yr.
- T = 0.001/(2x0.001) = 0.5 years
- Consistent with recent outbreak
✓ 0.5 years — recent transmission
Example 3
Deep Vertebrate Split
25% divergence, rate=0.001/yr.
- T = 0.25/(0.002) = 125 Ma
- Consistent with fossil record ~360 Ma — rate needs calibration
✓ 125 Ma (requires calibration
Real-World Applications
Phylogenetics
Date speciation events and build time-calibrated trees.
Viral Epidemiology
Date outbreak origins from sequence divergence.
Biogeography
Correlate clade divergence with geological events.
Microbial Evolution
Trace bacterial evolution and horizontal gene transfer.
Common Mistakes to Avoid
⚠️
Strict clock rarely holds
Mutation rates vary across lineages. Use relaxed clock models (BEAST).
⚠️
Mismatched gene and organism rate
mtDNA rate 20x faster than nuclear DNA. Match rate to sequence analyzed.
⚠️
No fossil calibration
Rates need fossil anchor dates for accuracy.
Frequently Asked Questions
What is the molecular clock? ▾
Mutations accumulate at approximately constant rate, allowing time estimation from sequence divergence.
What are typical mutation rates? ▾
mtDNA: 0.02/site/yr. Nuclear: 0.001. RNA viruses: 10^-3 to 10^-5.
Why does molecular clock sometimes disagree with fossils? ▾
Rate variation, missing fossils, calibration uncertainty, ancestral polymorphism.
What is a relaxed clock? ▾
Allows rate variation across branches. Implemented in BEAST/MrBayes.
How do you calibrate a clock? ▾
Use known fossil or biogeographic dates to set rate for specific lineages.