 A non-zero variance of Tajima’s estimator for two sequences even for infinitely many unlinked lociKing, Léandra, John Wakeley and Shai Carmi Theoretical Population Biology, 2018, vol. 122, issue C, 22-29 Abstract: The population-scaled mutation rate, θ, is informative on the effective population size and is thus widely used in population genetics. We show that for two sequences and n unlinked loci, the variance of Tajima’s estimator (θˆ), which is the average number of pairwise differences, does not vanish even as n→∞. The non-zero variance of θˆ results from a (weak) correlation between coalescence times even at unlinked loci, which, in turn, is due to the underlying fixed pedigree shared by gene genealogies at all loci. We derive the correlation coefficient under a diploid, discrete-time, Wright–Fisher model, and we also derive a simple, closed-form lower bound. We also obtain empirical estimates of the correlation of coalescence times under demographic models inspired by large-scale human genealogies. While the effect we describe is small (Varθˆ∕θ2≈ONe−1), it is important to recognize this feature of statistical population genetics, which runs counter to commonly held notions about unlinked loci. Keywords: Coalescent theory; Recombination; Heterozygosity; Effective population size; Pedigrees; Genealogies (search for similar items in EconPapers) Downloads: (external link) Related works: Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text Persistent link: https://EconPapers.repec.org/RePEc:eee:thpobi:v:122:y:2018:i:c:p:22-29 DOI: 10.1016/j.tpb.2017.03.002 Access Statistics for this article Theoretical Population Biology is currently edited by Jeremy Van Cleve More articles in Theoretical Population Biology from Elsevier |
Is your work missing from RePEc? Here is how to contribute.
Questions or problems? Check the EconPapers FAQ or send mail to .
EconPapers is hosted by the
School of Business at Örebro University.