Ratio between inbreeding and coancestry rates as a measure of population subdivision. Preliminary results

Abstract

Subdivision is one of the factors leading to increase in inbreeding higher than those expected regarding population size. Measuring population subdivision is not straightforward given that it is established rather diffuse. A measure of population subdivision from pedigrees is presented. It is based on the direct comparison of the increases in coancestry and the increases in inbreeding computed over equivalent discrete generation. Coancestry and inbreeding rates were established from the average of individual values of those parameters. The usefulness of the new parameter from a descriptive point of view is illustrated using a simulated population and two real populations with an opposed scenario regarding subdivision.