Sweepstakes reproduction or selective sweeps?

Bjarki Eldon, Postdoc in STE 325/17-2
in cooperation with Iulia Dahmer (SPP1590)

Natural highly fecund populations abound, and many have signifact economic impact. A key question regarding highly fecund populations is if they reproduce according to 'sweepstakes reproduction', i.e. where individuals have the capacity to produce numbers of offspring at least on the order of the population size, and such large reproduction events occur often enough to affect the evolution of the population. The classical models in population genetics, the Wright-Fisher diffusion and the Kingman-coalescent, do not capture the essential dynamics associated with sweepstakes reproduction, i.e. jumps in gene frequencies looking forward in time, and multiple mergers of ancestral lineages looking backward in time. However, multiple- merger coalescent processes can also be derived from models of natural selection without sweepstakes reproduction. We aim to investigate if we can distinguish be- tween genomic coalescent models derived from the Wright-Fisher model (or similar models) with 'strong selection', and genomic coalescent models derived from neutral models of sweepstakes reproduction, using whole-genome sequence data of two gadid species, Atlantic cod (Gadus morhua) and walleye pollock (Gadus chalcogrammus).