What does the selection coefficient measure?

The selection coefficient is a measure of the relative fitness of a particular genotype compared to others in the same population. It specifically quantifies how much less fit an inferior genotype is when compared to the most fit genotype. A selection coefficient close to zero indicates that the genotype is nearly as fit as the optimal genotype, while a value closer to one suggests that it is significantly less fit, meaning that individuals with this genotype will likely experience lower survival or reproduction rates.

In this context, the selection coefficient provides invaluable insights into how certain traits may be favored or disfavored in a population over time, allowing for a better understanding of evolutionary dynamics. This metric is critical in evolutionary biology because it helps researchers assess how natural selection operates on different genetic variations within a population.