Genetical Research



A statistical test for the difference in the amounts of DNA variation between two populations


HIDEKI  INNAN  a1 p1 and FUMIO  TAJIMA  a1 c1
a1 Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan

Abstract

A statistical test for the difference in the amounts of DNA variation between two populations is developed. The test statistic involves the covariance of the amount of variation between two populations, which is given by a function of their divergence time, T0. Accordingly, the power (rejection probability) of the test depends on T0. In this article, T0 is treated as unknown because it is very difficult to estimate. The test is most conservative when T0 = [infty infinity] is assumed because the covariance is zero. If T0 = 0 is assumed, the largest value of the rejection probability is obtained. Thus, the test provides a range of rejection probability unless we have a reliable estimate of T0. The test is applied to the PgiC region in three mustard species: Leavenworthia stylosa, L. crassa and L. uniflora. The results of our test show that the level of variation in L. stylosa is significantly higher than those in the other species.

(Received November 22 2001)
(Revised March 15 2002)


Correspondence:
c1 Corresponding author. Tel: +81 3 5841 4051. Fax: +81 3 3818 5399. e-mail: ftajima@biol.s.u-tokyo.ac.jp
p1 Present address: Department of Biological Science, University of Southern California, Los Angeles, CA 90089-1340, USA.


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