Non-monotonic effects of migration in populations with balancing selection
Pierangelo Lombardo, Andrea Gambassi, Luca Dall’Asta
(Submitted on 18 Oct 2013)

Balancing selection is recognized as a prominent evolutionary force responsible for the maintenance of genetic diversity in natural populations. We quantify its influence on the evolution of a subdivided population, investigating how the mean-fixation time (MFT) depends on the migration rate among subpopulations. We identify a threshold in the strength of the balancing selection above which the MFT changes its qualitative behavior compared to that of neutral populations, developing an unexpected non-monotonic dependence on the migration rate. This feature carries over into an analogous behavior of the heterozygosity, which is an index of the biodiversity of the population.