Enter biological fitness data
Example data table
| Genotype | Survival | Fecundity | Absolute fitness | Relative fitness |
|---|---|---|---|---|
| AA | 0.92 | 24 | 22.08 | 1.000 |
| Aa | 0.88 | 22 | 19.36 | 0.877 |
| aa | 0.81 | 20 | 16.20 | 0.734 |
Formula used
How to use this calculator
- Select direct absolute fitness or survival × fecundity mode.
- Enter values for AA, Aa, and aa.
- Choose the strongest genotype or set a custom reference.
- Add starting genotype frequencies for the population.
- Press the calculate button to view relative fitness, selection pressure, frequency shifts, and the graph.
- Use the CSV or PDF buttons to save the result set.
Frequently asked questions
1. What does relative fitness mean?
Relative fitness compares one genotype’s reproductive success with a reference genotype. A value of 1 means equal success. Lower values indicate reduced evolutionary performance under the chosen conditions.
2. Why is the strongest genotype often set to 1?
Using the highest absolute fitness as the reference makes comparisons easy. Every other genotype is scaled against the best performer, which is standard in many population genetics calculations.
3. Can I use survival and fecundity instead of absolute fitness?
Yes. In component mode, the calculator multiplies survival probability by fecundity for each genotype. That product becomes the genotype’s absolute fitness before normalization and comparison.
4. What is the selection coefficient?
The selection coefficient is calculated as 1 minus relative fitness. It measures how much a genotype is disadvantaged compared with the reference. Larger positive values indicate stronger negative selection.
5. Do genotype frequencies need to add up to 1?
No. This calculator normalizes the frequencies automatically. That means you can enter raw shares or approximate proportions, and the model rescales them before computing mean fitness and post-selection frequencies.
6. What does post-selection frequency show?
It estimates each genotype’s share after one round of selection. Genotypes with higher absolute fitness contribute more to the next generation, so their expected frequency usually rises.
7. Can relative fitness be greater than 1?
Yes, when you choose a custom reference smaller than a genotype’s absolute fitness. In standard maximum-reference scaling, the best genotype equals 1 and the others are usually 1 or below.
8. When is this calculator useful?
It is useful for population genetics classes, selection experiments, breeding studies, ecological comparisons, and quick evolutionary modeling where genotype performance must be compared consistently.