Large variance in reproductive success and the Ne/N ratio.
The ratio of the effective population size to adult (or census) population size (Ne/N) is an indicator of the extent of genetic variation expected in a population. It has been suggested that this ratio may be quite low for highly fecund species in which there is a sweepstakes-like chance of reproductive success, known as the Hedgecock effect. Here I show theoretically how the ratio may be quite small when there are only a few successful breeders (Nb) and that in this case, the Ne/N ratio is approximately Nb/N. In other words, high variance in reproductive success within a generation can result in a very low effective population size in an organism with large numbers of adults and consequently a very low Ne/N ratio. This finding appears robust when there is a large proportion of families with exactly two progeny or when there is random variation in progeny numbers among these families.
Hedrick
Philip
P
School of Life Sciences, Arizona State University, Tempe, Arizona 85287-4501, USA. philip.hedrick@asu.edu
D003247:Conservation of Natural Resources; D014644:Genetic Variation; D005828:Genetics, Population; D008954:Models, Biological; D011156:Population Density; D012098:Reproduction / Q000235:genetics*