Four-gamete test

In population genetics, the four-gamete test is a method for detecting historical recombination events. In population genetics, the four-gamete test is a method for detecting historical recombination events. Given a set of four or more sampled haploid chromosomes, the four-gamete test (FGT) detects recombination events by locating pairs of segregating sites that cannot have arisen without either recombination or a repeat mutation. Under the infinite-sites assumption (i.e. repeat mutations have zero probability), the probability of a repeat mutation is zero, and hence a recombination event is inferred. For example, if the data being studied consists of bi-allelic single-nucleotide polymorphism data, then the following configuration could be generated without recombination.