Recombination and the properties of Tajima's D in the context of approximate-likelihood calculation.

I show that Tajima's D, a commonly used summary of the site-frequency spectrum for single-nucleotide polymorphism data, is a biased summary of the site-frequency spectrum. Under neutral models, this bias depends on the population recombination rate. This bias of D in summarizing the data makes inference of demographic parameters sensitive to assumptions about recombination rates.