One measure, two names: Status number and variance effective size in plant genetic resources

Abstract In plant genetic resources research, coancestry-based parameters are widely used to assess the amount of diversity retained in germplasm samples, breeding populations and conservation collections. Among them, the variance effective number and status number are often treated as different measures. However, the analysis presented herein shows that they are algebraically equivalent when expressed under the same coancestry framework. Using standard definitions of average coancestry among individuals, average inbreeding, and group coancestry including self-coancestry, both parameters are derived to show that they reduce to the same expression. A numerical example confirms the identity. This result clarifies that the distinction is unnecessary. It also supports a more consistent interpretation of coancestry-based diversity measures in plant genetic resources.