A corollary of the nearly neutral theory of molecular evolution is that the efficiency of natural selection depends on effective population size. In this study, we evaluated the differences in levels of synonymous polymorphism among Drosophila species and showed that these differences can be explained by differences in effective population size. The differences can have implications for the mol...

—Effective population size (Ne) is an important concept in the management of threatened species like bull trout Salvelinus confluentus. General guidelines suggest that effective population sizes of 50 or 500 are essential to minimize inbreeding effects or maintain adaptive genetic variation, respectively. Although Ne strongly depends on census population size, it also depends on demographic and...

Previous theories on the effective size of age-structured populations assumed a constant environment and, usually, a constant population size and age structure. We derive formulas for the variance effective size of populations subject to fluctuations in age structure and total population size produced by a combination of demographic and environmental stochasticity. Haploid and monoecious or dio...