G. Luikart et al., DISTORTION OF ALLELE FREQUENCY-DISTRIBUTIONS PROVIDES A TEST FOR RECENT POPULATION BOTTLENECKS, The Journal of heredity, 89(3), 1998, pp. 238-247
We use population genetics theory and computer simulations to demonstr
ate that population bottlenecks cause a characteristic mode-shift dist
ortion in the distribution of allele frequencies at selectively neutra
l loci. Bottlenecks cause alleles at low frequency (<0.1) to become le
ss abundant than alleles in one or more intermediate allele frequency
class (e.g., 0.1-0.2), This distortion is transient and likely to be d
etectable for only a few dozen generations, Consequently only recent b
ottlenecks are likely to be detected by tests for distortions in distr
ibutions of allele frequencies. We illustrate and evaluate a qualitati
ve graphical method for detecting a bottleneck-induced distortion of a
llele frequency distributions. The simple novel method requires no inf
ormation on historical population sizes or levels of genetic variation
; it requires only samples of 5 to 20 polymorphic loci and approximate
ly 30 individuals. The graphical method often differentiates between e
mpirical datasets from bottlenecked and nonbottlenecked natural popula
tions. Computer simulations show that the graphical method is likely (
P > .80) to detect an allele frequency distortion after a bottleneck o
f less than or equal to 20 breeding individuals when 8 to 10 polymorph
ic microsatellite loci are analyzed.