Estimating demographic contributions to effective population size in an age-structured wild population experiencing environmental and demographic stochasticity

1.A population's effective size (Ne) is a key parameter that shapes rates of inbreeding and loss of genetic diversity, thereby influencing evolutionary processes and population viability. However estimating Ne, and identifying key demographic mechanisms that underlie the Ne to census population size (N) ratio, remains challenging, especially for small populations with overlapping generations and substantial environmental and demographic stochasticity and hence dynamic age-structure.

2.A sophisticated demographic method of estimating Ne/N, which uses Fisher's reproductive value to account for dynamic age-structure, has been formulated. However this method requires detailed individual- and population-level data on sex- and age-specific reproduction and survival, and has rarely been implemented.

3.Here we use the reproductive value method and detailed demographic data to estimate Ne/N for a small and apparently isolated red-billed chough (Pyrrhocorax pyrrhocorax) population of high c...