title: Determinants of effective population size for loci with different modes of inheritance.
abstract: Here we report an assessment of the determinants of effective population size (N(e)) in species with overlapping generations. Specifically, we used a stochastic demographic model to investigate the influence of different life-history variables on N(e)/N (where N = population census number) and the influence of sex differences in life-history variables on N(e) for loci with different modes of inheritance. We applied an individual-based modeling approach to two datasets: one from a natural population of savannah baboons (Papio cynocephalus) in the Amboseli basin of southern Kenya and one from a human tribal population (the Gainj of Papua New Guinea). Simulation-based estimates of N(e)/N averaged 0.329 for the Amboseli baboon population (SD = 0.116, 95% CI = 0.172 - 0.537) and 0.786 for the Gainj (SD = 0.184, 95% CI = 0.498 - 1.115). Although variance in male fitness had a substantial impact on N(e)/N in each of the two primate populations, ratios of N(e) values for autosomal and sex-linked loci exhibited no significant departures from Poisson-expected values. In each case, similarities in sex-specific N(e) values were attributable to the unexpectedly high variance in female fitness. Variance in male fitness resulted primarily from age-dependent variance in reproductive success, whereas variance in female fitness resulted primarily from stochastic variance in survival during the reproductive phase.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Biosciences West, Tucson, AZ 85721, USA. storz@email.arizona.edu
authors.forename: J F
authors.initials: JF
authors.lastname: Storz
authors.forename: U
authors.initials: U
authors.lastname: Ramakrishnan
authors.forename: S C
authors.initials: SC
authors.lastname: Alberts
mesh_terms: D000483:Alleles; D000818:Animals; D003710:Demography; D005298:Fertility; D005787:Gene Frequency; D005823:Genetics; D005828:Genetics, Population; D006801:Humans; D010215:Papio / Q000235:genetics; D011156:Population Density