Genetic effective size of a wild primate population: Influence of current and historical demography
Authored by U Ramakrishnan, JF Storz, SC Alberts
Date Published: 2002
Sponsors:
Alfred P. Sloan Foundation
United States National Institutes of Health (NIH)
United States Department of Energy (DOE)
United States National Science Foundation (NSF)
Platforms:
FSTAT
GENESCAN
Model Documentation:
Other Narrative
Mathematical description
Model Code URLs:
Model code not found
Abstract
A comprehensive assessment of the determinants of effective population
size (N(e)) requires estimates of variance in lifetime reproductive
success and past changes in census numbers. For natural populations, such information can be best obtained by combining longitudinal data on
individual life histories and genetic marker-based inferences of
demographic history. Independent estimates of the variance effective
size (N(eV), obtained from life-history data) and the inbreeding
effective size (N(eI), obtained from genetic data) provide a means of
disentangling the effects of current and historical demography. The
purpose of this study was to assess the demographic determinants of N(e)
in one of the most intensively studied natural populations of a
vertebrate species: the population of savannah baboons (Papio
cynocephalus) in the Amboseli Basin, southern Kenya. We tested the
hypotheses that N(eV) < N < N(eI) (where N=population census number) due
to a recent demographic bottleneck. N(eV) was estimated using a
stochastic demographic model based on detailed life-history data
spanning a 28-year period. Using empirical estimates of age-specific
rates of survival and fertility for both sexes, individual-based
simulations were used to estimate the variance in lifetime reproductive
success. The resultant values translated into an N(eV)/N estimate of
0.329 (SD=0.116, 95\% CI=0.172-0.537). Historical N(eI) was estimated
from 14-locus microsatellite genotypes using a coalescent-based
simulation model. Estimates of N(eI) were 2.2 to 7.2 times higher than
the contemporary census number of the Amboseli baboon population. In
addition to the effects of immigration, the disparity between historical
N(eI) and contemporary N is likely attributable to the time lag between
the recent drop in census numbers and the rate of increase in the
average probability of allelic identity-by-descent. Thus, observed
levels of genetic diversity may primarily reflect the population's
prebottleneck history rather than its current demography.
Tags
Reproductive success
Social-structure
Natural-populations
Subdivided populations
Indian fruit bat
Stepwise mutation model
Allele frequency data
Overlapping generations
Cynopterus sphinx
Neutral
alleles