A large value of Fst indicates what about genetic flow?

A large value of Fst reflects a substantial genetic differentiation between populations, which indicates restricted gene flow between these populations. Fst, or fixation index, is a measure that quantifies the proportion of genetic variance that can be attributed to differences between populations relative to the total genetic variance within the entire metapopulation. When Fst values are high, it suggests that the populations are more genetically distinct from one another, often due to limited migration or movement of individuals between them. This restricted gene flow can lead to populations evolving independently, potentially resulting in distinct adaptations or even speciation over time.

In contrast, lower Fst values suggest greater gene flow and more genetic homogeneity between populations, as more individuals are exchanging genes. This concept is crucial in evolutionary biology as it provides insights into population structure and the dynamics of natural selection versus gene flow in shaping genetic diversity.